Synthesis and Characterization of Mg-Ca-Zn(Sn) Bulk Metallic Glasses and Composites via Melt Spinning Followed by High-Pressure Torsion

In this work, the high-pressure torsion (HPT) technique is used to fabricate bulk metallic glass and composite samples of magnesium-rich Mg72Ca12Zn16 and Mg72Ca12Zn14Sn2 alloys. Mg72Ca12Zn14Sn2 is a new glass-forming alloy, and its glass-forming ability is slightly lower than that of the Mg72Ca12Zn16 alloy. Amorphous and composite ribbons of both alloys were subjected to HPT processing with 25, 50, and 70 turns separately to prepare bulk samples. For the amorphous samples, a homogeneous microstructure is achieved throughout the sample after 50 turns, and for the composite samples, microstructure homogenization is achieved after 70 turns. After the entire HPT process, no strain-induced crystallization was detected in both amorphous and composite samples. This study indicates that Mg-based metallic glasses and composites can be fabricated into bulk components even with low glass-forming ability. The microstructural refinement leads to a higher hardness than the starting material.