Influence of mechanically milled powder and high pressure on spark plasma sintering of Mg–Cu–Gd metallic glasses

In this study a gas atomized Mg65Cu25Gd10 amorphous powder was mechanically milled and consolidated by spark plasma sintering (SPS) at a high pressure (500 MPa) at different temperatures (443, 433, and 423 K) to provide an insight into the consolidation and mechanical behavior of Mg-based metallic glasses. Microstructural evolution in the vicinity of the interfaces of SPSed Mg–Cu–Gd BMG powders was characterized using scanning and transmission electron microscopy, and the associated amorphous phase transformation and thermal stability were analyzed using X-ray diffraction and differential scanning calorimetry. The results show that interfacial bonding between amorphous particles was enhanced by the disruption of surface oxides as well as by structural relaxation of the milled powder and the presence of high pressure during SPS. A finite element method with COMSOL software was also applied to investigate and explain the powder packing density, localized heating, and temperature distribution during SPS.