Tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 54 Nb 42 Al 4 metallic glass Fibers

Tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 54 Nb 42 Al 4 metallic glass Fibers | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 54 Nb 42 Al 4 metallic glass Fibers Ishtiaq Hussain, Zahid Hussain, Shamsher Ali, Iftikhar Ali This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4942241/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted 11 You are reading this latest preprint version Abstract In the current work, the tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 metallic glass (MG) fibers with a presizely controle different volume fractions (R) of bilayer coating i.e. , R = 0% to R = 95% is investigated by using electrochemical deposition technique. Experimental results reveal that yield stress, tensile stress and fracture stress is decreased with the increasing volume fractions (R) of bilayered Cu/Ni-coating. However the plastic strain is significantly increased with the increasing R values (R = 65% and above). The coating thickness and good interface bonding between two layers (Cu & Ni), as well as with the surface of MG fibers is responsible for larger enhancement in tensile plasticity of bilayered coated Ni − Nb-Al MG fibers. The plastic deformation of Cu/Ni bilayer electrodeposited MG fiber with a coating volume fraction, R = 95% is 5.8%. Electrochemical deposition of Cu/Ni bilayer onto Ni 52 Nb 42 Al 4 fibers can play a significant role in engineering applications. Electrochemical deposition MG fibers tensile plasticity volume fractions (R) Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction In the present study, Ternary Ni 52 Nb 42 Al 4 (at %) MG fibers were produced through melt-extraction technique, which shows good glass forming ability with high fracture strength, and high elastic deformation 1 . As cast NiNbAl metallic glass fibers exhibited highly brittle fracture without plastic deformation, especially under tensile loading at room temperature 1 – 3 . Monolayer Cu, Ni, Fe and Cu/Ni bilayer coating has been adopted to improve the plasticity of bulk metallic glasses under compressive loading at room temperature to avoid brittle fracture 4 – 6 . Literature review shows that different techniques have been used by different research groups to improve compressive plasticity in metallic glasses 5 , 6 . The most fissile and feasible approach is the electrochemical deposition of metals on the surface of metallic glasses 7 . Some other research groups are reported that, the electrochemical deposition of metallic surface layer onto the metallic glasses is a successful approach to improve the corresponding plasticity of metallic glasses at room temperature 8 . However improvement in plasticity is dependent on the thickness and quality of interface bonding of electrodeposited metal surface layer onto metallic glass fiber and the thickness of electrodeposited metal surface depends on the electrodeposition time duration 9 . Generally aqueous solutions have been used for electrochemical deposition of different metals onto the surface of metallic glasses 10 , 11 . One of the most important features of electrochemical deposition is that, it is easy to control the thickness of electrodeposits and their composition by the variation of electrochemical parameters especially electrochemical deposition time suration 12 . As-cast Ni 52 Nb 42 Al 4 MG fibers undergo linear elastic and heterogeneous deformation with highly catastrophic fracture without tensile plasticity 1 , 13 , 18 , however the tensile plasticity of Ni 52 Nb 42 Al 4 MG fibers can be improved by electrochemical deposition of Cu/Ni-bilayer onto the surface of MG fibers. Dense shear bands have been widely observed on the fracture surface of Cu/Ni-electrodeposited BMGs under compressive loading at room temperature 14 , 15 . Shear bands attract lot of research interest toward itself due to direct controlling of deformation behavior and plasticity 16 . Coating of a ductile metallic layer (Cu) onto the surface of MG fibers can successfully avert brittle fracture of MG fibers in tension 17 , 18 , and enhanced the tensile plasticity, but still there is no accessible data demonstrating the achieve of Cu/Ni-bilayer coating on tensile plasticity of micro-size MG fibers. For improvement of the tensile plasticity and solving problems allied to the realistic applications of Ni 52 Nb 42 Al 4 fibers in MEMS, magnetic devoice, sport equipment and robotic system. It is necessary to investigate the effect of ductile/hard metals electrodeposition on the tensile deformation behavior of Cu/Ni bilayer electrodeposited MG fibers. The uniaxial tension test was used to determine the mechanical characteristics of Cu/Ni bilayer electrodeposited MG fibers. The present article investigated the enhancement of tensile plasticity in Ni 52 Nb 42 Al 4 fibers with different volume ratios of bilayered coating, R = 0% to R = 95% at the strain rate of 1x10 − 4 s − 1 . The tensile plasticity is significantly enhanced with the increasing R value is discussed in detail. 2. Research Methodology The melt-extraction technique was used for the fabrication of Ni 52 Nb 42 Al 4 (at %) metallic glass fibers 1 . The master alloy ingots were remelted four times to insure homogeneity, for further detail please sees our previous article 1 . Cu/Ni-bilayer with different coating volume fractions (R), was electrodeposited onto the surface of extruded NiNbAl metallic glass fibers. Schematic illustration of Cu-electrochemical deposition onto MG fiber (specimen preparation) is shown in our previous work 18 . For electrochemical deposition of Cu/Ni bilayer onto Ni 52 Nb 42 Al 4 MG fibers, 2230G-30-1 Triple channel DC power supply (Keithley, A Tektronix Company) machine was used. The anode for Cu-coating was a soluble copper plate with 2mm width and 60mm height and for Ni-coating a nickel plate with 2mm width and 60mm height and the cathode was Ni 52 Nb 42 Al 4 MG fiber. Electrochemical deposition was performed in the constant current density of 1mA/mm 2 for metallic glass fibers with different coating volume ratios (R). The equations used for the calculation of current (I), volume ratio (R) and time (t) can be seen in our previous published article 18 . Before electrochemical deposition each fiber was cleaned with ethanol and rinsed with distil water. Cu/Ni bilayer of different R values was electrodeposited on the surface of Ni 56 Nb 44 MG fibers by electrochemical deposition in a solution bath with 150g/500ml CuSO 4 .5H 2 O and 10% H 2 SO 4 for Cu electrochemical deposition, 30g/500ml NiCl 2 .6H 2 O, 75g/500ml NiSo 4 .6H 2 O and then added 18g/500ml H 3 BO 3 for Ni-electrodeposition at room temperature. The current for anode of Ni are carefully controlled to attain constant molar ratio of Ni metal. For Cu-coating, Common acid sulfate solution was used, which exhibited good tensile ductility (11–16%) with relatively low yield strength of 120 MPa to 150 MPa 19 . For Ni-coating hard watts electrolyte was used, produced hard coating Ni-layer with a tensile strength 1000 MPa, but with limited plasticity 20 . The surface morphology and the diameters of the metallic glass fibers were determined in scanning electron microscope (SEM) (SU-1510, HITACHI company Japan) 1 . The amorphous nature of as-cast fibers was examined by the X-ray diffraction (XRD) with Cu-K α radiation in D/max-2550X-ray Diffract meter (D/max-255, Rigaku Company) 1 . Mechanical properties of Cu/Ni bilayer coated fibers were determine by Tension tests conducted in a MTF-100 machine with a gauge length of 20 mm and a constant strain rate of 1×10 − 4 s − 1 3 . 3. Results 3.1 Melt-extration technique and extrusion Ni 54 Nb 42 Al 4 MG fibers were extracted via melt-extraction technique. Schematic illustration of the melt-extraction process is shown in Fig. 1 a. To remove flaws and diameters variation in MG fibers, an extrusion process, i.e., cold drawing, were used to make the MG fibers smooth on the surface, and homogeneous in diameter, as shown in Fig. 1 c and 1 d. The as-cast fibers were pulled through a hard alloy mold along the direction indicated by the arrow as shown in Fig. 1 b. By using cold-drawing process, the diameter of the MG fiber was reduced, and the uniformity of the diameter of the MG fibers, and the roundness were consequently improved. The flawless extruded NiNbAl MG fibers are mentioned in Fig. 1 c & 1 d. The variation in diameter after cold-drawing the MG fibers are kept in the range from 70–180 µm. After the extrusion in the hard alloy moulds, the MG fibers are smooth, circular, and flawless, which are shown in Figs. 1 e and f. The extruded MG fibers exhibits improved mechanical properties under tensile loading at room temperature as compared to as-cast MG fibers. 3.2 XRD and DSC analysis of extruded MG fibers The volume ratio of Cu/Ni bialyer coating was different i.e. , R = 0%, R = 10%, R = 25%, R = 45%, R = 85% and R = 95% to insure the effect of different R values on tensile deformation behavior of Cu/Ni bilayer coated Ni − Nb-Al MG fibers. Figure 2 (a) shows XRD and inset (b) shows DSC curve of As-cast Ni 52 Nb 42 Al 4 MG fibers. The only single broad peak without substantial crystallization peaks exhibits the fully amorphous nature of metallic glass fibers 1 . Metals electrodeposited metallic glasses can undergo significant plastic deformation, at high quality metals electrochemical deposition 21 . To check the quality of electrochemical deposition before tensile test, we examined the cross-sectional area study of the mono Cu, Ni and Cu/Ni bialyer electrodeposited Ni 52 Nb 42 Al 4 MG fibers with different diameter, as shown in Figs. 3 a, b and c respectively. These figures shows uniform metal coating and good interface bonding between layers due to the continuous agitation of electrolyte and rotation of MG fiber. The coating thickness of Cu/Ni bilayer was different due to precisely control volume fractions (R) of bilayer coating for each specimen, i.e., R = 10%, R = 25% and R = 45%, 85% and 95%. 3.3 Surface morphology of Cu/Ni-coated NiNb Al glassy fibers The surface morphology of mono Cu and Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 MG fibers are shown in Fig. 4 a and b. The mono Cu and Cu/Ni bialyer electrodeposited MG fibers exhibited circular and smooth surfaces without grooves, flaws and scratches. The bilayered Cu/Ni bilayer electrodeposited MG fibers exhibited improve mechanical properties as compared to as cast and mono Cu and Ni-coated MG fibers. The effect of Cu/Ni bialyer electrochemical deposition on mechanical characteristics of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 MG fibers, were investigated and significant enhancement of tensile plasticity is observed for R = 85% and R = 95%, as shown in Figs. 5 a (e) and (f). Tensile stress-strain curves of the as-cast, as well as Cu/Ni bilayer electrodeposited Ni-Nb-Al fibers with different coating volume ratios (R), at the same strain rate 1x10 − 4 s − 1 , as shown in Fig. 5 a. Our experimental results revealed that, the stress-strain curves for as-cast as well as low R value (R = 10% to R = 45%) electrodeposited Ni-Nb MG fibers are fractured catastrophically without significant enhancement in tensile plasticity, as shown in Figs. 5 a (b-c), like bulk metallic glasses 22 and MG fibers 1 , 23 – 25 . Transition from brittle shear fracture to ductile fracture for Cu/Ni bilayer electrodeposited MG fibers can be observed for R = 45% to R = 95%, as shown in Fig. 5 a (d-f). 3.4 Mechanical properties of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 fibers The mechanical properties of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 MG fibers are strongly dependent on volume fractions (R) of Cu/Ni bialyer electrochemical deposition. The as-cast MG fiber is found to yield at 1884 MPa without plastic deformation before final fracture. Whereas Cu/Ni bilayer coated fibers with different R values are yielded at lower stress as compared to as-cast fibers. The mechanical properties, i.e., yield stress; tensile stress and fracture stress is decreased with the increasing R values, while plastic strain is increased with the increasing R value, as shown in Fig. 5 b. The Cu/Ni bilayer coated specimen with R = 95% yield at lowest strength 97.18 MPa, followed by a highest plastic strain of 5.8%, as shown in Fig. 5 a (f). The comparative study of mono Cu, Ni and Cu/Ni bialyer electrochemical deposition onto the surface of extruded Ni 52 Nb 42 Al 4 MG fibers with same coating volume fractions (R = 85%) at same strain rate 1x10 − 4 s − 1 illistrate that, the Cu/Ni bialyer electrodeposited Ni 52 Nb 42 Al 4 MG fiber yielded at 210 MPa with the highest plastic strain of 5.8%, as shown in Fig. 5 c (d). Most of metallic glasses and metallic glass fibers exhibited zero plasticity under tensile loading at room temperature 1 , 18 , 26 , therefore 5.8% tensile plasticity enhancement of highly brittle nature Ni 52 Nb 42 Al 4 MG fiber is a good sign for their engineering applications. The mechanical properties of comparative study of mono Cu, N-electrodeposited and Cu/Ni bilayer coated Ni 52 Nb 42 Al 4 MG fibers are shown in Fig. 5 d and Table 2. In order to further investigate the fracture process in coated samples under tensile loading at room temperature, a comprehensive study of fractographies was performed. Usually it is believed that, the fracture of MGs and MG fibers are initiated from inside of the sample and spread outside on whole the surface of the sample under tensile loading via tinny voids formation from the centre of the sample, as shown in Fig. 7 a, as mentioned in literature 7 , 18 , 27 . On further loading the size of the voids is increased and crack is initiated on both the sides in opposite direction, as shown in Fig. 7 b, literature also confirmed this kind of fracture behavior in metallic glasses under tensile loading 7 , 27 . Tensile fractographies of as-cast and Cu/Ni bialyer electrodeposited Ni 52 Nb 42 Al 4 MG fiber are shown, in Fig. 8 (a-h). The vein patterns seen on the surfaces of as-cast as well as low R values Cu/Ni bilayer coated MG fibers and the localization of deformation are due to shear softening in the shear bands 28 , as shown in Fig. 8 a and c. The viscous vein like patterns are changed into finger patterns, especially for higher R values, R = 85% and R = 95%, as shown in Fig. 8 e and g, such type of phenomena can also observed for different as cast MG fibers 1 , 29 – 31 . The vein patterns on the fracture surface of as-cast as well as low R values, as shown in Fig. 8 a and c, is changed into viscous fingering for higher R values, as shown in Fig. 8 e and g, which is the indication of mode-II fracture 32 – 34 . These findings indicate that, the tensile plasticity is significantly enhanced for thick (R = 95%) Cu/Ni bialyer coated Ni 52 Nb 42 Al 4 MG fibers as compared with the mono Cu and Ni-electrodeposited MG fibers. Multiple secondary shear bands are also clearly seen on the side surface of polished specimen with R = 95%, as shown in Fig. 8 h. These secondary shear bands are parallel to the direction of the fracture plane. Bilayer Cu/Ni-coating thickness is directly proportional to the coating time duration, as shown in Fig. 9 . We observed during dual bath electrochemical deposition of Cu/Ni bilayer onto the surfaces of MG fibers that, initially the rate of electrodeposition of Ni was higher as compared to Cu-electrodeposition but with the increasing coating time duration, the rate of Ni-coating is decreased, as shown in Fig. 6 Experimental results revealed that the value of yield strength is decreased with the increasing R values. We noted that the yield strength of coated MG fibers is dependent on volume ratio (R) of metal coating, especially under tensile loading at room temperature. The variations in the yield strength with the increasing R value are, due to larger blocking capacity of a thick Cu/Ni-coated layer on the surface of MG fiber. These results reveal that, enhancement of tensile plasticity in highly brittle nature MG fibers under tensile loading is possible by coating of a thick (R = 85% & R = 95%) Cu/Ni bialyer electrochemical deposition onto the surfaces of Ni 52 Nb 42 Al 4 MG fibers with precisely controlled volume fractions (R) of bilayer coating. 4. Discussion The electrochemical deposition of Cu/Ni bilayer onto the surface of BMGs, significantly affect the plastic deformation behavior of BMGs at room temperature [5, 6]. The uniaxial tension test was performed to determine the plasticity enhancement of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 MG fibers. Cu/Ni bialyer electrochemical deposition has strong consistency towards Ni-Nb-Al MG fibers and can successfully shield the fibers from external forces and acidic environment. Electrochemical deposition of metals on the surface of fibers is an issue of great importance for the constancy and effectiveness of practical application in complex environments 35 . We obtained uniform bilayer coating of Cu/Ni onto Ni 52 Nb 42 Al 4 MG fibers by keeping electrolyte stirred and current density of 1mA/mm − 2 . Electrochemical deposition technique specially coating of Cu/Ni bilayer onto MG fibers, the residual stress in Nano crystalline deposits can leads to decrease in fracture strength of electrodeposited MG fibers 36 , 37 , as shown in Fig. 5 b, with the enhancement of coating volume ratio, R. Due to bilayered Cu/Ni-coating onto the surfaces of MG fibers, the tensile stress is decrease with the larger R values, due to larger residual stress, as shown in Fig. 5 b and d 37 . The mechanical properties of as-cast, as well as, mono Cu, Ni and Cu/Ni-coated Ni 52 Nb 42 Al 4 MG fibers are summarized in Table 1 and 2. The data illistrate that, the yield stress of as-cast Ni 56 Nb 44 MG fiber is 1730 MPa higher than that (730 MPa) of R = 10% Cu/Ni bilayer electrodeposited MG fiber. The fracture strength and tensile strength are decreased, while plastic strain is increased with the increasing volume ratios, R (%) of metals coating. The coating thickness of Cu/Ni bilayer was different, due to precisely control volume ratios i.e., R = 10%, R = 25%, R = 45%, R = 85% and R = 95% respectively. This is evidence in the softening effect of Cu/Ni bilayer electrochemical deposition [9]. The highest plastic strain is 5.8% for volume ratio, R = 95%. To control volume ratios, (R) of bilayer coating, the electrochemical deposition time duration was kept constant for each R value by using the following equation: $$\:t=\frac{{t}_{o}R}{{R}_{to}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(1\right)$$ Where t is the time required for a specific volume ratio (R) R = volume ratio $$\:{R}_{t0}=\frac{{V}_{t}}{{V}_{o+{V}_{t}}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(2\right)$$ V t is the volume of metal coated for a specific time duration, i.e.,(5minutes) V o is the original volume of MG fiber V o =L. \(\:\frac{\pi\:\left({d1}^{2}-{do}^{2}\right)}{4}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(3\right)\) Where, L is the length of coated MG fiber, do is the original diameter of MG fiber and d1 is the diameter of metal coated fiber. The deformation behavior of MG fibers resistant material with tensile force applied corresponding to the `extensive fiber axis. $$\:{{\sigma\:}}_{\text{c}\:\:}={\text{v}}_{\text{f}}{{\sigma\:}}_{\text{f}}+\:{\text{v}}_{\text{m}}{{\sigma\:}}_{\text{m}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(4\right)$$ Eq 4 shows the stress-strain behavior of fiber unspecified to be tested separately. Metallic glass fiber show high strength and very high strength to density ratio; these properties cause to be them gorgeous in aerospace applications 38 . The uniaxial stress-strain response of MG fiber can be divided into several stages. In the stage I, the strain is small and fiber deform elastically. Our MG fibers are linear elastically deformed, so we have, $$\:{{\sigma\:}}_{\text{c}}={\text{E}}_{\text{c}}{{\epsilon\:}}_{\text{c}}-{{\epsilon\:}}_{\text{c}}\left[{\text{V}}_{\text{f}\:}{\text{E}}_{\text{f}}+{\text{V}}_{\text{m}}{{\epsilon\:}}_{\text{m}}\right]\:\:\:\left(\text{S}\text{t}\text{a}\text{g}\text{e}\:\text{I}\right)\:\:\:\:\:\left(5\right)$$ In some fibers reinforced materials, the matrix deforms permanently at a strain at which the fiber remain elastic. This is stage II deformation, for which, $$\:{{\sigma\:}}_{\text{c}}=\:{\text{v}}_{\text{f}}{\text{E}}_{\text{f}\:}{{\epsilon\:}}_{\text{c}}+{\text{v}}_{\text{m}}{{\sigma\:}}_{\text{m}}\left({{\epsilon\:}}_{\text{c}\:}\right)\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(6\right)$$ Where \(\:{{\sigma\:}}_{\text{m}}\left({{\epsilon\:}}_{\text{c}}\right)\) is assumed to be the stress carried by the matrix as determine from a tensile test of the matrix [38]. The stage II modulus \(\:{\text{E}}_{\text{f}}\) is define as the instantaneous slope of the composite, stress-strain curve during stage II deformation that is, $$\:{\text{E}}_{\text{c}}=\frac{{\text{d}{\sigma\:}}_{\text{c}}}{{\text{d}{\epsilon\:}}_{\text{c}}}=\:{V}_{f}{E}_{f}+\:{V}_{m}\left(\frac{{d\sigma\:}_{m}}{{dϵ}_{c}}\right)\:\:\:\:\:\left(StageII\right)\:\left(7\right)$$ In most cases the second term of Eq. 7 is much less than the first so that $$\:{\text{E}}_{\text{c}}=\:{\text{V}}_{\text{f}}{\text{E}}_{\text{f}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(8\right)$$ Although \(\:\frac{{\text{d}{\sigma\:}}_{\text{m}}}{{\text{d}{\epsilon\:}}_{\text{c}}}\) is presumed to be the slope of the stress-strain curve of the electrodeposited fibers tested by itself 38 . This is not always the case during stage II is that of a constrained matrix. The sufficiency of the estimate of Eq. 8 depends on the volume of \(\:{\text{V}}_{\text{f}}{\text{E}}_{\text{f}}\) relative to the second term of Eq. 7 provided V is satisfactorily larger. Eq. 8 remains a rational estimate for the secondary modulus. Many high strength fibers do not deformed permanently before fracture. So the tensile strain of such fiber is frequently found in stage II. While thick bilayer Cu/Ni-coated MG fibers usually deform plastically before fracture, such fibers shows stage III in their tensile curves, as shown in Fig. 4 a and c. The volume fraction ratio express during stage III is, $$\:{{\sigma\:}}_{\text{c}}\left({{\epsilon\:}}_{\text{c}}\right)=\:{\text{V}}_{\text{f}}{{\sigma\:}}_{\text{f}}\left({{\epsilon\:}}_{\text{c}}\right)+\:{\text{V}}_{\text{m}}{{\sigma\:}}_{\text{m}}\left({{\epsilon\:}}_{\text{c}}\right)\:\left(\:\text{s}\text{t}\text{a}\text{g}\text{e}\:\text{I}\text{I}\text{I}\right)\:\:\:\:\:\left(9\right)$$ In the Eq. 9 \(\:{{\sigma\:}}_{\text{f}}{{\epsilon\:}}_{\text{c}}\) and \(\:{{\sigma\:}}_{\text{m}}{{\epsilon\:}}_{\text{c}}\) are the comparative wire and matrix flow stresses at the multiplestrain \(\:{{\epsilon\:}}_{\text{c}}\) .The three stage deformation behavior of bilayered Cu/Ni-electrodeposited MG fiber is described in Fig. 6 . Figure 5 a ((b)-(d)) is suitable when only the first two stages of wires deform are observed. In stage I the fiber and Ni-electrodeposited layer deform elastically. In stage II matrix deform plastically and wire deform elastically, thus the slope of stress-strain curve is reduce, while in stage III both matrix and wire deform plastically. The wire fracture strain \(\:\left({\text{E}}_{\text{f}}\right)\) is less than that of matrix. Matrix fracture is not essentially simultaneous with wire fracture, so a secondary tensile strength \(\:\left({\text{V}}_{\text{m}}\:\right({\text{T}.\text{S}.)}_{\text{m}})\) is observed. MG fibers tension strength is instantaneous with fiber fracture; this strength is articulated as follow, $$\:\left({\text{T}.\text{S}.)}_{\text{c}}=\:{\text{V}}_{\text{f}}{\left(\text{T}.\text{S}.\right)}_{\text{f}}+\:{\text{V}}_{\text{m}}{{\sigma\:}}_{\text{m}}{({\epsilon\:}}_{\text{f}}\right)\:\:\:\:\:\:\:\:\:\:\:\:\:\left(10\right)$$ In the above Eq. 10, \(\:{(\text{T}.\text{S}.)}_{\text{c}}\) is the wire tension strength and \(\:{{\sigma\:}}_{\text{m}}{({\epsilon\:}}_{\text{f}})\) is the matrix flow stress at the MG fiber fracture strain \(\:{{\epsilon\:}}_{\text{f}}\) . Tensile fracture surface morphology of Cu/Ni bilayer electrodeposited Ni 56 Nb 44 fiber revealed that dense veins like patterns originated on the tensile fracture surface of as-cast and low R value Cu/Ni bialyer electrodeposited Ni 56 Nb 44 MG fibers, while secondary shear bands are originated from side surface of tensile fracture sample with R = 95%, as shown in Fig. 8 h, while single shear bands can be observed on fracture surface of un-coated fiber, as shown in Fig. 8 b. These factors mean that crystalline phase during electrodeposition of bilayered Cu/Ni onto fibers block the shear bands propagation, resulting in a delocalization of neighboring un-deformed regions. Increase plasticity of fibers is expected due to this shear delocalization 39 . The beginning, dissemination, and more branching of shear bands is the signal of enhancement of plasticity in bilayered coated fibers. Thus plasticity of coated fiber is reliant frankly on the concentration of shear bands formation during deformation 40 . Thick Cu/Ni-electrodeposition onto the surfaces of Ni 52 Nb 42 Al 4 fibers inhibited the fast propagation of primary shear band and promoted the secondary shear bands, as represented in Fig. 5 h, as a result the plasticity is increased 41 . However our experimental results revealed that there should be a considerable thick Cu/Ni bilayer (100µm and above) the surface of fibers, as shown in Fig. 5 a (d-f). The plasticity enhancement using electrochemically deposited Cu/Ni-bilayer described to an excellent bonding between Ni 52 Nb 42 Al 4 fibers and Cu/Ni-deposited layer. The soft Cu- electrodeposited layer can stop the fast propagation of single shear band and Ni-electrodeposited layer can defuse uniformity with the amorphous fibers layer and be appreciably extended without rupture 10 , 21 . Finally the tensile plasticity enhancement could be connected with the thickness, quality of electrodeposits and good interface bonding between Cu and Ni-coated layers, as well as with the surface of MG fibers. 5. Conclusions The tensile plasticity enhancement of Cu/Ni bilayer electrodeposited Ni 52 Nb 42 Al 4 metallic glaay fibers with different volume fractions (R) of bilayered coating were determined by using tension test. Tension test results reveal that a maximum tensile plasticity of 5.8% have been achieved for R = 95% Cu/Ni bialyer coated Ni 52 Nb 42 Al 4 MG fibers. Thick Cu/Ni bialyer electrochemical deposition onto the MG fibers hindered the initiation and fast propagation of primary shear bands and enhanced the tensile plasticity of coated Ni-Nb-Al fibers. Basically, the homogeneous Cu/Ni bilayer coating, coating thickness and good interface bonding between layers is responsible for enhancement of tensile plasticity in coated MG fibers. The improvement in the tensile plasticity is due to electrodeposition of a thick Cu/Ni-bilayer is a break through to enhance the reliability and application of highly brittle nature Ni 52 Nb 42 Al 4 MG fibers as functional, electronic and engineering materials. The novelty of the current work is the first time enhancement of tensile plasticity in ternary Ni 52 Nb 42 Al 4 fibers by Cu/Ni bialyer coating under tensile loading at room temperature. The current exploration may open up a new perspective to understand the enhancement of tensile plasticity in MG fibers by Cu/Ni bialyer electrochemical deposition. Declarations Acknowledgements This work was financially supported by Karakoram International University Gilgit. Ref: KIU-ORIC-(2022-23. Data availability . The data in this work are available from the corresponding author on reasonable request. Authors Contribution. Ishtiaq Hussain and Zahid Hussain imitated the project, I. Hussain and Z. 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Nanocrystallization enabled tensile ductility of Co-based amorphous microwires. Scripta Materialia , 66 1041-1044 (2012). Takayama, S. Drawing of Pd 77.5 Cu 6 Si 16.5 metallic glass wires. Mat . Sci . Eng . 38 41-48 (1979). Hagiwara, M. et al. Mechanical properties of Fe-Si-B amorphous wires produced by in-rotating-water spinning method. Metallurgical Transactions A , 13 373-382 (1982). Sun, H. et al. Tensile Strength Reliability Analysis of Cu 48 Zr 48 Al 4 Amorphous Microwires. Metals , 6 296 (2016). Sun, B.A. et al. Origin of Shear Stability and Compressive Ductility Enhancement of Metallic Glasses by Metal Coating. Sci Rep , 6 27852 (2016). Gu, X.J. et al. Compressive plasticity and toughness of a Ti-based bulk metallic glass. Acta Materialia , 58 1708-1720 (2010). Yi, . J. Wang, W.H. & Lewandowski, J.J. Guiding and Deflecting Cracks in Bulk Metallic Glasses to Increase Damage Tolerance. Adv Eng Mat , 17 620-625 (2015). Yu, P. et al. Enhancement of Strength and Corrosion Resistance of Copper Wires by Metallic Glass Coating . Materials Transactions , 50 2451-2454 (2009). Drory, M.D. et al. On the decohesion of residually stressed thin films. Acta Metallurgica, 36 2019-2028 (1988). Ziebell, T.D. & Schuh, C.A. Residual stress in electrodeposited nanocrystalline nickel-tungsten coatings. J . Mat . Res , 27 1271-1284 (2012). Courtney, T.H. Mechanical Behaviors of Materials. science . 2 252-255 (1990). .39. Neurohr, K. Electrodeposition of metals. Journal of Electrochemical Society . 162 256-264 (2015). Li, B. et al. Fundamental constraints on the strength of transition-metal borides: The case of CrB4. Phy . Rev . B . 87 (2013). . Qiu, S.B & Yao, K.F. Novel application of the electrodeposition on bulk metallic glasses. Appl . Surf . Sci . 255 3454-3458 (2008). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 21 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 14 Oct, 2024 Reviews received at journal 09 Oct, 2024 Reviews received at journal 05 Oct, 2024 Reviewers agreed at journal 21 Sep, 2024 Reviewers agreed at journal 21 Sep, 2024 Reviewers agreed at journal 20 Sep, 2024 Reviewers invited by journal 20 Sep, 2024 Editor assigned by journal 19 Sep, 2024 Editor invited by journal 05 Sep, 2024 Submission checks completed at journal 03 Sep, 2024 First submitted to journal 20 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4942241","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":358675212,"identity":"88109a82-7099-41cb-8691-0bf83b2d385c","order_by":0,"name":"Ishtiaq Hussain","email":"data:image/png;base64,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","orcid":"","institution":"Karakorum International University","correspondingAuthor":true,"prefix":"","firstName":"Ishtiaq","middleName":"","lastName":"Hussain","suffix":""},{"id":358675214,"identity":"47542ceb-ae53-493d-93d5-e03647d33dda","order_by":1,"name":"Zahid Hussain","email":"","orcid":"","institution":"Karakorum International University","correspondingAuthor":false,"prefix":"","firstName":"Zahid","middleName":"","lastName":"Hussain","suffix":""},{"id":358675215,"identity":"e5cc558a-ff81-42e6-b3dc-aea66200a462","order_by":2,"name":"Shamsher Ali","email":"","orcid":"","institution":"Karakorum International University","correspondingAuthor":false,"prefix":"","firstName":"Shamsher","middleName":"","lastName":"Ali","suffix":""},{"id":358675217,"identity":"b8326920-949b-4439-bcd8-b6d2890a166f","order_by":3,"name":"Iftikhar Ali","email":"","orcid":"","institution":"Karakorum International University","correspondingAuthor":false,"prefix":"","firstName":"Iftikhar","middleName":"","lastName":"Ali","suffix":""}],"badges":[],"createdAt":"2024-08-20 05:38:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4942241/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4942241/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-96997-2","type":"published","date":"2025-07-21T15:56:51+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":65943606,"identity":"dcbb584b-e45e-486e-8b52-4c669f782c5a","added_by":"auto","created_at":"2024-10-04 17:03:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":158302,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Schematic illustration of the melt-extraction technique. \u003cstrong\u003eb\u003c/strong\u003e Schematic illustration of cold-drawing process. \u003cstrong\u003eC\u003c/strong\u003e and d are Profiles of extruded NiNbAl MG fibers. \u003cstrong\u003eE \u0026amp; f\u003c/strong\u003e SEM image showing smooth and flawless surface quality of NiNbAl -MG fiber.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/8e8d4e6f835f62e9a4f586b5.png"},{"id":65943605,"identity":"b5addc7a-4bdd-4a4c-94e6-24c9cf65a352","added_by":"auto","created_at":"2024-10-04 17:03:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":132592,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eXRD and DSC analysis of Ni\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e52\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eNb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e42\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003csub\u003e \u003c/sub\u003e\u003cstrong\u003emetallic glass fibers.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(a)\u0026nbsp;\u0026nbsp;\u0026nbsp; XRD and Inset (b) DSC curve of Ni\u003csub\u003e54\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4,\u003c/sub\u003e MG fiber.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/9a97f536ac46e935237cc41e.png"},{"id":65943607,"identity":"25bd41d2-b884-4013-a00a-78a9763ab265","added_by":"auto","created_at":"2024-10-04 17:03:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":98221,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM surface images of Cu and Ni-electrodeposited\u003c/strong\u003e \u003cstrong\u003eNi\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e52\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eNb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e42\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e MG\u0026nbsp; fibers. \u003c/strong\u003e(a) Shows Cu-coated MG wire, (b) shows bilayered Cu/Ni-coated-MG wire and inset (c) shows high magnification images of Cu/Ni- electrodeposited Ni-Nb-Al MG wires.\u0026nbsp;\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/54d441a6d5dcf5a20ecaa058.png"},{"id":65944652,"identity":"e1a3903d-98e0-413e-b20b-4a739a76c33d","added_by":"auto","created_at":"2024-10-04 17:19:08","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":335670,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM cross-section images of momo Cu, Ni and bilayered Cu/Ni-coated Ni\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e52\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eNb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e42\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e MG fibers. \u003c/strong\u003e(a) Shows Cu-coated MG wire, (b) shows Ni-coated-MG wire (c) shows bilayered Cu/Ni- electrodeposited Ni-Nb-Al MG wires.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/7c37b1284f9ec6bea375f71c.png"},{"id":65943608,"identity":"f33f43c6-9293-4d07-8f68-534a8f78f4ac","added_by":"auto","created_at":"2024-10-04 17:03:08","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":345953,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eShows stress-strain curves for tensile deformation behavior of bilayered Cu/Ni-electrodeposited Ni-Nb-Al\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eMG fibers with different R values. \u003c/strong\u003e(a) shows stress-strain curves of bilayered Cu/Ni-coated Ni-Nb-Al MG fibers with different R values, (b) shows mechanical properties of bilayered Cu/Ni-coated MG fibers, (c) shows tensile stress-strain curves of as-cast, mono Cu, Ni and bilayered Cu/Ni-coated Ni-Nb-Al MG fibers, (d) shows mechanical properties of as-cast \u0026amp; Cu, Ni and Cu/Ni-coated MG fibers.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/06b611f33793f99531ac9bcc.png"},{"id":65944321,"identity":"79615009-f176-4dbc-bca3-61e02c2c8d8d","added_by":"auto","created_at":"2024-10-04 17:11:08","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":23305,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFive stages tensile déformation behavoir of bilayer Cu/Ni-coated Ni\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e52\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eNb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e42\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4 \u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eMG fiber with the R=75%\u003c/strong\u003e. In stage I, the bilayer Cu/Ni-coated fiber deform linearly. In stage II, the coating deforms plastically while the wire core elastically. In stage III, both the coating and the MG fiber deform plastically. In stage IV, the MG wire core fractures. In stage V, the coating necks and then fractures.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/041b71bd9427a7385d7776a7.png"},{"id":65943611,"identity":"14af29d4-4b45-4da2-bde1-029f4a5544a7","added_by":"auto","created_at":"2024-10-04 17:03:08","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":32009,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic representation of voids formation and voids cracking system in bilayered Cu/Ni-coated Ni-Nb-Al MG fiber on tensile loading, \u003c/strong\u003e(a) voids formation from the center of coated sample,(b) voids crack opening system of bilayered coated sample.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/4f96b47d0bf0c5bfe50e838e.png"},{"id":65943613,"identity":"3e83156c-83a6-4825-bd38-03807daec554","added_by":"auto","created_at":"2024-10-04 17:03:08","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":2085629,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)-(f) shows fractographies of as-cast and Cu/Ni-coated Ni\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e52\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eNb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e42\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eAl\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e MG fibers. \u003c/strong\u003e(a) As-cast Ni-Nb-Al MG fiber shows generation of few vein patterns on fracture surface,\u003cstrong\u003e \u003c/strong\u003e(b) As-cast MG fiber shows single shear band on fracture surface\u003cstrong\u003e \u003c/strong\u003e(c) and (d) shows bilayered Cu/Ni-coated Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fiber with dense vein patterns on fracture surfaces, (e) \u0026amp; (f) shows dense vein patterns changes into viscous fingering with R=85% on fracture surface of Cu/Ni-coated MG fibers.\u003cstrong\u003e \u003c/strong\u003e(g) shows transition of viscous fingering into dimples\u003cstrong\u003e, \u003c/strong\u003e(h) Shows shear bands on side surface of Cu/Ni-electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e\u003csub\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/sub\u003efiber.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/bfd90427183062248cacf33f.png"},{"id":65944323,"identity":"0ef64936-1004-4147-8268-2c204174a314","added_by":"auto","created_at":"2024-10-04 17:11:10","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":30715,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eShows relationship between increasing R values with the coating thickness and of bilayered Cu/Ni- electrodeposited MG fibers.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/2c1c4f9298925c49283febe8.png"},{"id":87756541,"identity":"5bc5d7fa-0a0c-4aa9-a86c-c5430d7379fa","added_by":"auto","created_at":"2025-07-28 15:59:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5602019,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4942241/v1/574f6b10-c259-48b9-839c-806d1a3e843b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 54 Nb 42 Al 4 metallic glass Fibers","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn the present study, Ternary Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e (at %) MG fibers were produced through melt-extraction technique, which shows good glass forming ability with high fracture strength, and high elastic deformation\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. As cast NiNbAl metallic glass fibers exhibited highly brittle fracture without plastic deformation, especially under tensile loading at room temperature\u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Monolayer Cu, Ni, Fe and Cu/Ni bilayer coating has been adopted to improve the plasticity of bulk metallic glasses under compressive loading at room temperature to avoid brittle fracture\u003csup\u003e\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Literature review shows that different techniques have been used by different research groups to improve compressive plasticity in metallic glasses\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. The most fissile and feasible approach is the electrochemical deposition of metals on the surface of metallic glasses\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Some other research groups are reported that, the electrochemical deposition of metallic surface layer onto the metallic glasses is a successful approach to improve the corresponding plasticity of metallic glasses at room temperature\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHowever improvement in plasticity is dependent on the thickness and quality of interface bonding of electrodeposited metal surface layer onto metallic glass fiber and the thickness of electrodeposited metal surface depends on the electrodeposition time duration\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Generally aqueous solutions have been used for electrochemical deposition of different metals onto the surface of metallic glasses\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. One of the most important features of electrochemical deposition is that, it is easy to control the thickness of electrodeposits and their composition by the variation of electrochemical parameters especially electrochemical deposition time suration\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAs-cast Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers undergo linear elastic and heterogeneous deformation with highly catastrophic fracture without tensile plasticity\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, however the tensile plasticity of Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers can be improved by electrochemical deposition of Cu/Ni-bilayer onto the surface of MG fibers. Dense shear bands have been widely observed on the fracture surface of Cu/Ni-electrodeposited BMGs under compressive loading at room temperature\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Shear bands attract lot of research interest toward itself due to direct controlling of deformation behavior and plasticity\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Coating of a ductile metallic layer (Cu) onto the surface of MG fibers can successfully avert brittle fracture of MG fibers in tension\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, and enhanced the tensile plasticity, but still there is no accessible data demonstrating the achieve of Cu/Ni-bilayer coating on tensile plasticity of micro-size MG fibers. For improvement of the tensile plasticity and solving problems allied to the realistic applications of Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers in MEMS, magnetic devoice, sport equipment and robotic system. It is necessary to investigate the effect of ductile/hard metals electrodeposition on the tensile deformation behavior of Cu/Ni bilayer electrodeposited MG fibers.\u003c/p\u003e \u003cp\u003eThe uniaxial tension test was used to determine the mechanical characteristics of Cu/Ni bilayer electrodeposited MG fibers. The present article investigated the enhancement of tensile plasticity in Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers with different volume ratios of bilayered coating, R\u0026thinsp;=\u0026thinsp;0% to R\u0026thinsp;=\u0026thinsp;95% at the strain rate of 1x10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003es\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The tensile plasticity is significantly enhanced with the increasing R value is discussed in detail.\u003c/p\u003e"},{"header":"2. Research Methodology","content":"\u003cp\u003eThe melt-extraction technique was used for the fabrication of Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e (at %) metallic glass fibers\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. The master alloy ingots were remelted four times to insure homogeneity, for further detail please sees our previous article\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eCu/Ni-bilayer with different coating volume fractions (R), was electrodeposited onto the surface of extruded NiNbAl metallic glass fibers.\u003c/p\u003e \u003cp\u003eSchematic illustration of Cu-electrochemical deposition onto MG fiber (specimen preparation) is shown in our previous work\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. For electrochemical deposition of Cu/Ni bilayer onto Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers, 2230G-30-1 Triple channel DC power supply (Keithley, A Tektronix Company) machine was used. The anode for Cu-coating was a soluble copper plate with 2mm width and 60mm height and for Ni-coating a nickel plate with 2mm width and 60mm height and the cathode was Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fiber.\u003c/p\u003e \u003cp\u003eElectrochemical deposition was performed in the constant current density of 1mA/mm\u003csup\u003e2\u003c/sup\u003e for metallic glass fibers with different coating volume ratios (R). The equations used for the calculation of current (I), volume ratio (R) and time (t) can be seen in our previous published article\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. Before electrochemical deposition each fiber was cleaned with ethanol and rinsed with distil water. Cu/Ni bilayer of different R values was electrodeposited on the surface of Ni\u003csub\u003e56\u003c/sub\u003eNb\u003csub\u003e44\u003c/sub\u003e MG fibers by electrochemical deposition in a solution bath with 150g/500ml CuSO\u003csub\u003e4\u003c/sub\u003e.5H\u003csub\u003e2\u003c/sub\u003eO and 10% H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e for Cu electrochemical deposition, 30g/500ml NiCl\u003csub\u003e2\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO, 75g/500ml NiSo\u003csub\u003e4\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO and then added 18g/500ml H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e for Ni-electrodeposition at room temperature. The current for anode of Ni are carefully controlled to attain constant molar ratio of Ni metal. For Cu-coating, Common acid sulfate solution was used, which exhibited good tensile ductility (11\u0026ndash;16%) with relatively low yield strength of 120 MPa to 150 MPa\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. For Ni-coating hard watts electrolyte was used, produced hard coating Ni-layer with a tensile strength 1000 MPa, but with limited plasticity\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe surface morphology and the diameters of the metallic glass fibers were determined in scanning electron microscope (SEM) (SU-1510, HITACHI company Japan)\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. The amorphous nature of as-cast fibers was examined by the X-ray diffraction (XRD) with Cu-K\u003csub\u003eα\u003c/sub\u003e radiation in D/max-2550X-ray Diffract meter (D/max-255, Rigaku Company)\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Mechanical properties of Cu/Ni bilayer coated fibers were determine by Tension tests conducted in a MTF-100 machine with a gauge length of 20 mm and a constant strain rate of 1\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1 3\u003c/sup\u003e.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Melt-extration technique and extrusion\u003c/h2\u003e\n \u003cp\u003eNi\u003csub\u003e54\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers were extracted via melt-extraction technique. Schematic illustration of the melt-extraction process is shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea. To remove flaws and diameters variation in MG fibers, an extrusion process, i.e., cold drawing, were used to make the MG fibers smooth on the surface, and homogeneous in diameter, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec and \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed. The as-cast fibers were pulled through a hard alloy mold along the direction indicated by the arrow as shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eb. By using cold-drawing process, the diameter of the MG fiber was reduced, and the uniformity of the diameter of the MG fibers, and the roundness were consequently improved. The flawless extruded NiNbAl MG fibers are mentioned in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec \u0026amp; \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed. The variation in diameter after cold-drawing the MG fibers are kept in the range from 70\u0026ndash;180 \u0026micro;m. After the extrusion in the hard alloy moulds, the MG fibers are smooth, circular, and flawless, which are shown in Figs. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ee and f. The extruded MG fibers exhibits improved mechanical properties under tensile loading at room temperature as compared to as-cast MG fibers.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 XRD and DSC analysis of extruded MG fibers\u003c/h2\u003e\n \u003cp\u003eThe volume ratio of Cu/Ni bialyer coating was different \u003cem\u003ei.e.\u003c/em\u003e, R\u0026thinsp;=\u0026thinsp;0%, R\u0026thinsp;=\u0026thinsp;10%, R\u0026thinsp;=\u0026thinsp;25%, R\u0026thinsp;=\u0026thinsp;45%, R\u0026thinsp;=\u0026thinsp;85% and R\u0026thinsp;=\u0026thinsp;95% to insure the effect of different R values on tensile deformation behavior of Cu/Ni bilayer coated Ni\u003csub\u003e\u0026minus;\u003c/sub\u003eNb-Al MG fibers. Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(a) shows XRD and inset (b) shows DSC curve of As-cast Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers. The only single broad peak without substantial crystallization peaks exhibits the fully amorphous nature of metallic glass fibers\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Metals electrodeposited metallic glasses can undergo significant plastic deformation, at high quality metals electrochemical deposition\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eTo check the quality of electrochemical deposition before tensile test, we examined the cross-sectional area study of the mono Cu, Ni and Cu/Ni bialyer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers with different diameter, as shown in Figs. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea, b and c respectively. These figures shows uniform metal coating and good interface bonding between layers due to the continuous agitation of electrolyte and rotation of MG fiber. The coating thickness of Cu/Ni bilayer was different due to precisely control volume fractions (R) of bilayer coating for each specimen, i.e., R\u0026thinsp;=\u0026thinsp;10%, R\u0026thinsp;=\u0026thinsp;25% and R\u0026thinsp;=\u0026thinsp;45%, 85% and 95%.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 Surface morphology of Cu/Ni-coated NiNb Al glassy fibers\u003c/h2\u003e\n \u003cp\u003eThe surface morphology of mono Cu and Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers are shown in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea and b. The mono Cu and Cu/Ni bialyer electrodeposited MG fibers exhibited circular and smooth surfaces without grooves, flaws and scratches. The bilayered Cu/Ni bilayer electrodeposited MG fibers exhibited improve mechanical properties as compared to as cast and mono Cu and Ni-coated MG fibers.\u003c/p\u003e\n \u003cp\u003eThe effect of Cu/Ni bialyer electrochemical deposition on mechanical characteristics of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers, were investigated and significant enhancement of tensile plasticity is observed for R\u0026thinsp;=\u0026thinsp;85% and R\u0026thinsp;=\u0026thinsp;95%, as shown in Figs. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea (e) and (f). Tensile stress-strain curves of the as-cast, as well as Cu/Ni bilayer electrodeposited Ni-Nb-Al fibers with different coating volume ratios (R), at the same strain rate 1x10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea. Our experimental results revealed that, the stress-strain curves for as-cast as well as low R value (R\u0026thinsp;=\u0026thinsp;10% to R\u0026thinsp;=\u0026thinsp;45%) electrodeposited Ni-Nb MG fibers are fractured catastrophically without significant enhancement in tensile plasticity, as shown in Figs. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea (b-c), like bulk metallic glasses\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e and MG fibers\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. Transition from brittle shear fracture to ductile fracture for Cu/Ni bilayer electrodeposited MG fibers can be observed for R\u0026thinsp;=\u0026thinsp;45% to R\u0026thinsp;=\u0026thinsp;95%, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea (d-f).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Mechanical properties of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers\u003c/h2\u003e\n \u003cp\u003eThe mechanical properties of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers are strongly dependent on volume fractions (R) of Cu/Ni bialyer electrochemical deposition. The as-cast MG fiber is found to yield at 1884 MPa without plastic deformation before final fracture. Whereas Cu/Ni bilayer coated fibers with different R values are yielded at lower stress as compared to as-cast fibers. The mechanical properties, i.e., yield stress; tensile stress and fracture stress is decreased with the increasing R values, while plastic strain is increased with the increasing R value, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb. The Cu/Ni bilayer coated specimen with R\u0026thinsp;=\u0026thinsp;95% yield at lowest strength 97.18 MPa, followed by a highest plastic strain of 5.8%, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea (f). The comparative study of mono Cu, Ni and Cu/Ni bialyer electrochemical deposition onto the surface of extruded Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers with same coating volume fractions (R\u0026thinsp;=\u0026thinsp;85%) at same strain rate 1x10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e illistrate that, the Cu/Ni bialyer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fiber yielded at 210 MPa with the highest plastic strain of 5.8%, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec (d). Most of metallic glasses and metallic glass fibers exhibited zero plasticity under tensile loading at room temperature\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, therefore 5.8% tensile plasticity enhancement of highly brittle nature Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fiber is a good sign for their engineering applications. The mechanical properties of comparative study of mono Cu, N-electrodeposited and Cu/Ni bilayer coated Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers are shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ed and Table\u0026nbsp;2.\u003c/p\u003e\n \u003cp\u003eIn order to further investigate the fracture process in coated samples under tensile loading at room temperature, a comprehensive study of fractographies was performed. Usually it is believed that, the fracture of MGs and MG fibers are initiated from inside of the sample and spread outside on whole the surface of the sample under tensile loading via tinny voids formation from the centre of the sample, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea, as mentioned in literature\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1728060436.png\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eOn further loading the size of the voids is increased and crack is initiated on both the sides in opposite direction, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eb, literature also confirmed this kind of fracture behavior in metallic glasses under tensile loading\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1728060435.png\"\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cp\u003eTensile fractographies of as-cast and Cu/Ni bialyer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fiber are shown, in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e(a-h). The vein patterns seen on the surfaces of as-cast as well as low R values Cu/Ni bilayer coated MG fibers and the localization of deformation are due to shear softening in the shear bands\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ea and c. The viscous vein like patterns are changed into finger patterns, especially for higher R values, R\u0026thinsp;=\u0026thinsp;85% and R\u0026thinsp;=\u0026thinsp;95%, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ee and g, such type of phenomena can also observed for different as cast MG fibers\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. The vein patterns on the fracture surface of as-cast as well as low R values, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ea and c, is changed into viscous fingering for higher R values, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ee and g, which is the indication of mode-II fracture\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. These findings indicate that, the tensile plasticity is significantly enhanced for thick (R\u0026thinsp;=\u0026thinsp;95%) Cu/Ni bialyer coated Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers as compared with the mono Cu and Ni-electrodeposited MG fibers.\u003c/p\u003e\n \u003cp\u003eMultiple secondary shear bands are also clearly seen on the side surface of polished specimen with R\u0026thinsp;=\u0026thinsp;95%, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003eh. These secondary shear bands are parallel to the direction of the fracture plane. Bilayer Cu/Ni-coating thickness is directly proportional to the coating time duration, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e. We observed during dual bath electrochemical deposition of Cu/Ni bilayer onto the surfaces of MG fibers that, initially the rate of electrodeposition of Ni was higher as compared to Cu-electrodeposition but with the increasing coating time duration, the rate of Ni-coating is decreased, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003eExperimental results revealed that the value of yield strength is decreased with the increasing R values. We noted that the yield strength of coated MG fibers is dependent on volume ratio (R) of metal coating, especially under tensile loading at room temperature. The variations in the yield strength with the increasing R value are, due to larger blocking capacity of a thick Cu/Ni-coated layer on the surface of MG fiber. These results reveal that, enhancement of tensile plasticity in highly brittle nature MG fibers under tensile loading is possible by coating of a thick (R\u0026thinsp;=\u0026thinsp;85% \u0026amp; R\u0026thinsp;=\u0026thinsp;95%) Cu/Ni bialyer electrochemical deposition onto the surfaces of Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers with precisely controlled volume fractions (R) of bilayer coating.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe electrochemical deposition of Cu/Ni bilayer onto the surface of BMGs, significantly affect the plastic deformation behavior of BMGs at room temperature [5, 6]. The uniaxial tension test was performed to determine the plasticity enhancement of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers. Cu/Ni bialyer electrochemical deposition has strong consistency towards Ni-Nb-Al MG fibers and can successfully shield the fibers from external forces and acidic environment. Electrochemical deposition of metals on the surface of fibers is an issue of great importance for the constancy and effectiveness of practical application in complex environments\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe obtained uniform bilayer coating of Cu/Ni onto Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers by keeping electrolyte stirred and current density of 1mA/mm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. Electrochemical deposition technique specially coating of Cu/Ni bilayer onto MG fibers, the residual stress in Nano crystalline deposits can leads to decrease in fracture strength of electrodeposited MG fibers\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, with the enhancement of coating volume ratio, R. Due to bilayered Cu/Ni-coating onto the surfaces of MG fibers, the tensile stress is decrease with the larger R values, due to larger residual stress, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003eb and d\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe mechanical properties of as-cast, as well as, mono Cu, Ni and Cu/Ni-coated Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers are summarized in Table\u0026nbsp;1 and 2. The data illistrate that, the yield stress of as-cast Ni\u003csub\u003e56\u003c/sub\u003eNb\u003csub\u003e44\u003c/sub\u003e MG fiber is 1730 MPa higher than that (730 MPa) of R\u0026thinsp;=\u0026thinsp;10% Cu/Ni bilayer electrodeposited MG fiber. The fracture strength and tensile strength are decreased, while plastic strain is increased with the increasing volume ratios, R (%) of metals coating. The coating thickness of Cu/Ni bilayer was different, due to precisely control volume ratios i.e., R\u0026thinsp;=\u0026thinsp;10%, R\u0026thinsp;=\u0026thinsp;25%, R\u0026thinsp;=\u0026thinsp;45%, R\u0026thinsp;=\u0026thinsp;85% and R\u0026thinsp;=\u0026thinsp;95% respectively. This is evidence in the softening effect of Cu/Ni bilayer electrochemical deposition [9]. The highest plastic strain is 5.8% for volume ratio, R\u0026thinsp;=\u0026thinsp;95%.\u003c/p\u003e \u003cp\u003eTo control volume ratios, (R) of bilayer coating, the electrochemical deposition time duration was kept constant for each R value by using the following equation:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:t=\\frac{{t}_{o}R}{{R}_{to}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere t is the time required for a specific volume ratio (R)\u003c/p\u003e \u003cp\u003eR\u0026thinsp;=\u0026thinsp;volume ratio\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:{R}_{t0}=\\frac{{V}_{t}}{{V}_{o+{V}_{t}}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(2\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eV\u003csub\u003et\u003c/sub\u003e is the volume of metal coated for a specific time duration, i.e.,(5minutes)\u003c/p\u003e \u003cp\u003eV\u003csub\u003eo\u003c/sub\u003e is the original volume of MG fiber\u003c/p\u003e \u003cp\u003eV\u003csub\u003eo\u003c/sub\u003e=L.\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\pi\\:\\left({d1}^{2}-{do}^{2}\\right)}{4}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(3\\right)\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eWhere, L is the length of coated MG fiber, do is the original diameter of MG fiber and d1 is the diameter of metal coated fiber.\u003c/p\u003e \u003cp\u003eThe deformation behavior of MG fibers resistant material with tensile force applied corresponding to the `extensive fiber axis.\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\:{{\\sigma\\:}}_{\\text{c}\\:\\:}={\\text{v}}_{\\text{f}}{{\\sigma\\:}}_{\\text{f}}+\\:{\\text{v}}_{\\text{m}}{{\\sigma\\:}}_{\\text{m}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(4\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eEq 4 shows the stress-strain behavior of fiber unspecified to be tested separately. Metallic glass fiber show high strength and very high strength to density ratio; these properties cause to be them gorgeous in aerospace applications\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. The uniaxial stress-strain response of MG fiber can be divided into several stages. In the stage I, the strain is small and fiber deform elastically. Our MG fibers are linear elastically deformed, so we have,\u003cdiv id=\"Equd\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equd\" name=\"EquationSource\"\u003e\n$$\\:{{\\sigma\\:}}_{\\text{c}}={\\text{E}}_{\\text{c}}{{\\epsilon\\:}}_{\\text{c}}-{{\\epsilon\\:}}_{\\text{c}}\\left[{\\text{V}}_{\\text{f}\\:}{\\text{E}}_{\\text{f}}+{\\text{V}}_{\\text{m}}{{\\epsilon\\:}}_{\\text{m}}\\right]\\:\\:\\:\\left(\\text{S}\\text{t}\\text{a}\\text{g}\\text{e}\\:\\text{I}\\right)\\:\\:\\:\\:\\:\\left(5\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn some fibers reinforced materials, the matrix deforms permanently at a strain at which the fiber remain elastic. This is stage II deformation, for which,\u003cdiv id=\"Eque\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Eque\" name=\"EquationSource\"\u003e\n$$\\:{{\\sigma\\:}}_{\\text{c}}=\\:{\\text{v}}_{\\text{f}}{\\text{E}}_{\\text{f}\\:}{{\\epsilon\\:}}_{\\text{c}}+{\\text{v}}_{\\text{m}}{{\\sigma\\:}}_{\\text{m}}\\left({{\\epsilon\\:}}_{\\text{c}\\:}\\right)\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(6\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\sigma\\:}}_{\\text{m}}\\left({{\\epsilon\\:}}_{\\text{c}}\\right)\\)\u003c/span\u003e\u003c/span\u003e is assumed to be the stress carried by the matrix as determine from a tensile test of the matrix [38]. The stage II modulus \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{E}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e is define as the instantaneous slope of the composite, stress-strain curve during stage II deformation that is,\u003cdiv id=\"Equf\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equf\" name=\"EquationSource\"\u003e\n$$\\:{\\text{E}}_{\\text{c}}=\\frac{{\\text{d}{\\sigma\\:}}_{\\text{c}}}{{\\text{d}{\\epsilon\\:}}_{\\text{c}}}=\\:{V}_{f}{E}_{f}+\\:{V}_{m}\\left(\\frac{{d\\sigma\\:}_{m}}{{dϵ}_{c}}\\right)\\:\\:\\:\\:\\:\\left(StageII\\right)\\:\\left(7\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn most cases the second term of Eq.\u0026nbsp;7 is much less than the first so that\u003cdiv id=\"Equg\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equg\" name=\"EquationSource\"\u003e\n$$\\:{\\text{E}}_{\\text{c}}=\\:{\\text{V}}_{\\text{f}}{\\text{E}}_{\\text{f}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(8\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eAlthough \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{{\\text{d}{\\sigma\\:}}_{\\text{m}}}{{\\text{d}{\\epsilon\\:}}_{\\text{c}}}\\)\u003c/span\u003e\u003c/span\u003eis presumed to be the slope of the stress-strain curve of the electrodeposited fibers tested by itself \u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis is not always the case during stage II is that of a constrained matrix. The sufficiency of the estimate of Eq.\u0026nbsp;8 depends on the volume of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\text{V}}_{\\text{f}}{\\text{E}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e relative to the second term of Eq.\u0026nbsp;7 provided V is satisfactorily larger. Eq.\u0026nbsp;8 remains a rational estimate for the secondary modulus. Many high strength fibers do not deformed permanently before fracture. So the tensile strain of such fiber is frequently found in stage II. While thick bilayer Cu/Ni-coated MG fibers usually deform plastically before fracture, such fibers shows stage III in their tensile curves, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003ea and c. The volume fraction ratio express during stage III is,\u003cdiv id=\"Equh\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equh\" name=\"EquationSource\"\u003e\n$$\\:{{\\sigma\\:}}_{\\text{c}}\\left({{\\epsilon\\:}}_{\\text{c}}\\right)=\\:{\\text{V}}_{\\text{f}}{{\\sigma\\:}}_{\\text{f}}\\left({{\\epsilon\\:}}_{\\text{c}}\\right)+\\:{\\text{V}}_{\\text{m}}{{\\sigma\\:}}_{\\text{m}}\\left({{\\epsilon\\:}}_{\\text{c}}\\right)\\:\\left(\\:\\text{s}\\text{t}\\text{a}\\text{g}\\text{e}\\:\\text{I}\\text{I}\\text{I}\\right)\\:\\:\\:\\:\\:\\left(9\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the Eq.\u0026nbsp;9\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\sigma\\:}}_{\\text{f}}{{\\epsilon\\:}}_{\\text{c}}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\sigma\\:}}_{\\text{m}}{{\\epsilon\\:}}_{\\text{c}}\\)\u003c/span\u003e\u003c/span\u003e are the comparative wire and matrix flow stresses at the multiplestrain\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\epsilon\\:}}_{\\text{c}}\\)\u003c/span\u003e\u003c/span\u003e.The three stage deformation behavior of bilayered Cu/Ni-electrodeposited MG fiber is described in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003ea ((b)-(d)) is suitable when only the first two stages of wires deform are observed. In stage I the fiber and Ni-electrodeposited layer deform elastically. In stage II matrix deform plastically and wire deform elastically, thus the slope of stress-strain curve is reduce, while in stage III both matrix and wire deform plastically. The wire fracture strain \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\left({\\text{E}}_{\\text{f}}\\right)\\)\u003c/span\u003e\u003c/span\u003e is less than that of matrix. Matrix fracture is not essentially simultaneous with wire fracture, so a secondary tensile strength \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\left({\\text{V}}_{\\text{m}}\\:\\right({\\text{T}.\\text{S}.)}_{\\text{m}})\\)\u003c/span\u003e\u003c/span\u003e is observed. MG fibers tension strength is instantaneous with fiber fracture; this strength is articulated as follow,\u003cdiv id=\"Equi\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equi\" name=\"EquationSource\"\u003e\n$$\\:\\left({\\text{T}.\\text{S}.)}_{\\text{c}}=\\:{\\text{V}}_{\\text{f}}{\\left(\\text{T}.\\text{S}.\\right)}_{\\text{f}}+\\:{\\text{V}}_{\\text{m}}{{\\sigma\\:}}_{\\text{m}}{({\\epsilon\\:}}_{\\text{f}}\\right)\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(10\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the above Eq.\u0026nbsp;10, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{(\\text{T}.\\text{S}.)}_{\\text{c}}\\)\u003c/span\u003e\u003c/span\u003e is the wire tension strength and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\sigma\\:}}_{\\text{m}}{({\\epsilon\\:}}_{\\text{f}})\\)\u003c/span\u003e\u003c/span\u003e is the matrix flow stress at the MG fiber fracture strain\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{{\\epsilon\\:}}_{\\text{f}}\\)\u003c/span\u003e\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTensile fracture surface morphology of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e56\u003c/sub\u003eNb\u003csub\u003e44\u003c/sub\u003e fiber revealed that dense veins like patterns originated on the tensile fracture surface of as-cast and low R value Cu/Ni bialyer electrodeposited Ni\u003csub\u003e56\u003c/sub\u003eNb\u003csub\u003e44\u003c/sub\u003e MG fibers, while secondary shear bands are originated from side surface of tensile fracture sample with R\u0026thinsp;=\u0026thinsp;95%, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e8\u003c/span\u003eh, while single shear bands can be observed on fracture surface of un-coated fiber, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e8\u003c/span\u003eb. These factors mean that crystalline phase during electrodeposition of bilayered Cu/Ni onto fibers block the shear bands propagation, resulting in a delocalization of neighboring un-deformed regions. Increase plasticity of fibers is expected due to this shear delocalization\u003csup\u003e39\u003c/sup\u003e. The beginning, dissemination, and more branching of shear bands is the signal of enhancement of plasticity in bilayered coated fibers. Thus plasticity of coated fiber is reliant frankly on the concentration of shear bands formation during deformation\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Thick Cu/Ni-electrodeposition onto the surfaces of Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers inhibited the fast propagation of primary shear band and promoted the secondary shear bands, as represented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003eh, as a result the plasticity is increased\u003csup\u003e41\u003c/sup\u003e. However our experimental results revealed that there should be a considerable thick Cu/Ni bilayer (100\u0026micro;m and above) the surface of fibers, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003ea (d-f).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe plasticity enhancement using electrochemically deposited Cu/Ni-bilayer described to an excellent bonding between Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers and Cu/Ni-deposited layer. The soft Cu- electrodeposited layer can stop the fast propagation of single shear band and Ni-electrodeposited layer can defuse uniformity with the amorphous fibers layer and be appreciably extended without rupture\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. Finally the tensile plasticity enhancement could be connected with the thickness, quality of electrodeposits and good interface bonding between Cu and Ni-coated layers, as well as with the surface of MG fibers.\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThe tensile plasticity enhancement of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e metallic glaay fibers with different volume fractions (R) of bilayered coating were determined by using tension test. Tension test results reveal that a maximum tensile plasticity of 5.8% have been achieved for R\u0026thinsp;=\u0026thinsp;95% Cu/Ni bialyer coated Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers. Thick Cu/Ni bialyer electrochemical deposition onto the MG fibers hindered the initiation and fast propagation of primary shear bands and enhanced the tensile plasticity of coated Ni-Nb-Al fibers. Basically, the homogeneous Cu/Ni bilayer coating, coating thickness and good interface bonding between layers is responsible for enhancement of tensile plasticity in coated MG fibers. The improvement in the tensile plasticity is due to electrodeposition of a thick Cu/Ni-bilayer is a break through to enhance the reliability and application of highly brittle nature Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e MG fibers as functional, electronic and engineering materials.\u003c/p\u003e \u003cp\u003eThe novelty of the current work is the first time enhancement of tensile plasticity in ternary Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers by Cu/Ni bialyer coating under tensile loading at room temperature. The current exploration may open up a new perspective to understand the enhancement of tensile plasticity in MG fibers by Cu/Ni bialyer electrochemical deposition.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by Karakoram International University Gilgit. Ref: KIU-ORIC-(2022-23.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e. The data in this work are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors Contribution.\u0026nbsp;\u003c/strong\u003eIshtiaq Hussain and Zahid Hussain imitated the project, I. Hussain and Z. Hussain performed the experiments and write manuscript. Iftikhar Ali and Shamsher Ali contributed to data analyzing and discussion.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional Information.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e. The authors declared that we have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHussain, I. et al. Cooling rate-dependent yield behavior of metallic glass wires. \u003cem\u003eMat\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Sci\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Eng\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e A\u003c/em\u003e \u003cstrong\u003e683\u003c/strong\u003e, 236-243 (2017).\u003c/li\u003e\n\u003cli\u003eArgon, A.S. Plastic deformation in metallic glasses. \u003cem\u003eActa Metallurgica\u003c/em\u003e, \u003cstrong\u003e27\u003c/strong\u003e 47-58 (1979).\u003c/li\u003e\n\u003cli\u003eSpaepen, F. 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Novel application of the electrodeposition on bulk metallic glasses. \u003cem\u003eAppl\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Surf\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Sci\u003c/em\u003e. \u003cstrong\u003e255\u003c/strong\u003e 3454-3458 (2008).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Electrochemical deposition, MG fibers, tensile plasticity, volume fractions (R)","lastPublishedDoi":"10.21203/rs.3.rs-4942241/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4942241/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn the current work, the tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e metallic glass (MG) fibers with a presizely controle different volume fractions (R) of bilayer coating \u003cem\u003ei.e.\u003c/em\u003e, R\u0026thinsp;=\u0026thinsp;0% to R\u0026thinsp;=\u0026thinsp;95% is investigated by using electrochemical deposition technique. Experimental results reveal that yield stress, tensile stress and fracture stress is decreased with the increasing volume fractions (R) of bilayered Cu/Ni-coating. However the plastic strain is significantly increased with the increasing R values (R\u0026thinsp;=\u0026thinsp;65% and above). The coating thickness and good interface bonding between two layers (Cu \u0026amp; Ni), as well as with the surface of MG fibers is responsible for larger enhancement in tensile plasticity of bilayered coated Ni\u003csub\u003e\u0026minus;\u003c/sub\u003eNb-Al MG fibers. The plastic deformation of Cu/Ni bilayer electrodeposited MG fiber with a coating volume fraction, R\u0026thinsp;=\u0026thinsp;95% is 5.8%. Electrochemical deposition of Cu/Ni bilayer onto Ni\u003csub\u003e52\u003c/sub\u003eNb\u003csub\u003e42\u003c/sub\u003eAl\u003csub\u003e4\u003c/sub\u003e fibers can play a significant role in engineering applications.\u003c/p\u003e","manuscriptTitle":"Tensile mechanical behavior of Cu/Ni bilayer electrodeposited Ni 54 Nb 42 Al 4 metallic glass Fibers","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-04 17:03:02","doi":"10.21203/rs.3.rs-4942241/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-14T04:48:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-09T10:35:46+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-05T08:59:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"75860507845302552555026312980014008050","date":"2024-09-21T12:55:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"335531557926649601629966974515234318170","date":"2024-09-21T12:35:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"224642107687779920521067983552001480706","date":"2024-09-20T14:03:26+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-09-20T11:18:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-19T19:30:37+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-09-06T03:07:38+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-09-03T15:07:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2024-08-20T05:36:43+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"786fec5d-bb5e-430a-899b-0aa6f9e997f7","owner":[],"postedDate":"October 4th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-28T15:58:36+00:00","versionOfRecord":{"articleIdentity":"rs-4942241","link":"https://doi.org/10.1038/s41598-025-96997-2","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-07-21 15:56:51","publishedOnDateReadable":"July 21st, 2025"},"versionCreatedAt":"2024-10-04 17:03:02","video":"","vorDoi":"10.1038/s41598-025-96997-2","vorDoiUrl":"https://doi.org/10.1038/s41598-025-96997-2","workflowStages":[]},"version":"v1","identity":"rs-4942241","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4942241","identity":"rs-4942241","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}