Aging behavior of as-cast AlMo0.5NbTa0.5TiZr refractory high-entropy alloy

Aging behavior of as-cast AlMo0.5NbTa0.5TiZr refractory high-entropy alloy | 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 Research Article Aging behavior of as-cast AlMo 0.5 NbTa 0.5 TiZr refractory high-entropy alloy Mohammadreza Mokhtare, Milad Zohrevand, Haniyeh Moradjoo Hamedani, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7635857/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In this study, the effect of aging heat treatment on the microstructure, phase transformation, and mechanical properties of as-cast AlMo 0.5 NbTa 0.5 TiZr refractory high-entropy alloy has been investigated. The samples were directly aged (aging of the as-cast samples without prior homogenization) at 900, 1000, and 1100 °C for 2, 5, and 10 hours. The results showed that increasing the aging time or temperature leads to a gradual homogenization of dendritic (DR) and interdendritic (IDR) regions, removing the elemental segregated regions as the coring effect and the formation and growth of secondary precipitates (mainly the Zr/Al-rich HCP phase). The X-ray diffraction analyses and thermodynamic simulations confirmed that the light elements (Al, Zr) tend to diffuse toward the IDR regions, while the heavy elements (Mo, Nb, Ta) remained inside the DR regions with BCC structure. The hardness measurements indicated that the maximum hardness (754 HV) is achieved after aging at 1000 °C for 5 hours. The formation of fine HCP precipitates inside the DR phase and an increase in the fraction of IDR phase were found to be responsible for the increase in hardness. Further increase in the aging temperature or time caused the excessive coarsening of secondary precipitates and a dramatic decrease in the fracture toughness. This study indicated that the as-cast AlMo 0.5 NbTa 0.5 TiZr is thermally unstable and tends to decompose to a multi-phase structure. Materials Engineering Diffusion RHEA Thermal stability Precipitation Dendritic structure Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-7635857","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":516268046,"identity":"3122db18-8550-4c30-aa56-39b8131c67d9","order_by":0,"name":"Mohammadreza Mokhtare","email":"","orcid":"","institution":"1.\tDepartment of Materials Science and Engineering, Hamedan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Mohammadreza","middleName":"","lastName":"Mokhtare","suffix":""},{"id":516268953,"identity":"687c4087-2a56-4fe4-b5c7-a93b2f4a0776","order_by":1,"name":"Milad 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treatment on the microstructure, phase transformation, and mechanical properties of as-cast AlMo\u003csub\u003e0.5\u003c/sub\u003eNbTa\u003csub\u003e0.5\u003c/sub\u003eTiZr refractory high-entropy alloy has been investigated. The samples were directly aged (aging of the as-cast samples without prior homogenization) at 900, 1000, and 1100 °C for 2, 5, and 10 hours. The results showed that increasing the aging time or temperature leads to a gradual homogenization of dendritic (DR) and interdendritic (IDR) regions, removing the elemental segregated regions as the coring effect and the formation and growth of secondary precipitates (mainly the Zr/Al-rich HCP phase). The X-ray diffraction analyses and thermodynamic simulations confirmed that the light elements (Al, Zr) tend to diffuse toward the IDR regions, while the heavy elements (Mo, Nb, Ta) remained inside the DR regions with BCC structure. The hardness measurements indicated that the maximum hardness (754 HV) is achieved after aging at 1000 °C for 5 hours. The formation of fine HCP precipitates inside the DR phase and an increase in the fraction of IDR phase were found to be responsible for the increase in hardness. Further increase in the aging temperature or time caused the excessive coarsening of secondary precipitates and a dramatic decrease in the fracture toughness. 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