Relaxation and Devitrification of MgZnCa Metallic Glass.

MgZnCa metallic glass is a promising biodegradable material due to its high strength, corrosion resistance, and excellent glass-forming ability. In this study, we investigated its thermal stability, structural relaxation, and crystallization behavior using high-energy synchrotron-based X-ray diffraction and DSC analysis. The glass exhibits a wide supercooled liquid region of 58 K, allowing for thermoplastic forming. Structural relaxation experiments revealed nearly a complete relaxation in the first cycle below the first crystallization peak. Upon heating, the alloy undergoes a complex, multi-step devitrification involving successive formation of crystalline phases: MgZn (orthorhombic), Mg (hexagonal), and a Ca-Mg-Zn intermetallic compound CaMgZn, denoted as . Phase identification was carried out by Rietveld refinement, and the evolution of lattice parameters demonstrated anisotropic thermal expansion, particularly in the MgZn phase. Notably, the presence of the CaMgZn, with the 4.6 ≤ ≤ 12 phase reported in earlier studies, was not confirmed. This work deepens the understanding of phase stability and crystallization mechanisms in Mg-based metallic glasses and supports their future application in biodegradable implants.