Development of a magnesium/amorphous nano-SiO2 composite using accumulative extrusion method

Abstract In this study, a Mg-X%SiO2 (X = 1, 2) nanocomposite was developed using amorphous silica nanoparticles via the accumulative extrusion method. The reinforcement phase was added to the matrix between extrusion passes. The study evaluated the mechanical properties of the composite samples via compression and hardness tests, while the microstructure and texture were analyzed using an optical microscope and X-ray diffraction analysis. To remove the deformation history and examine the effect of the reinforcement phase on mechanical properties, the samples were annealed in an argon atmosphere. In addition, monolithic magnesium samples were fabricated through the same process to serve as a basis for comparison. This study revealed that adding 1 wt.% amorphous silica nanoparticles to the magnesium matrix improved the overall mechanical properties. However, the nanocomposites displayed varying properties in different directions. Along the extrusion direction, the yield strength and ductility increased up to 57% and 5%, respectively, while the ultimate compressive strength decreased by about 8%. Along the normal direction, the yield strength and ductility increased up to 37% and 45%, respectively, while the ultimate compressive strength decreased by about 9%. The Mg/2%SiO2 nanocomposite sample showed superior Brinell hardness. The number of extrusion passes had a significant impact on the distribution of nanoparticles within the matrix. The optical microscope micrographs revealed that the reinforcement phase was uniformly distributed throughout the matrix, and no agglomeration of nanoparticles was observed. The X-ray diffraction results demonstrated that the texture of nanocomposite samples weakened after adding nanoparticles, resulting in improved ductility.