Mg–Y–Cu bulk metallic glass prepared by mechanical alloying and vacuum hot-pressing

We have studied the amorphization behavior of Mg85−xY15Cux (x=20–40) alloy powders synthesized by mechanical alloying technique. The as-milled powders were mainly amorphous after 10 h of milling. The thermal stability of these Mg85−xY15Cux glassy powders was investigated by differential scanning calorimeter (DSC). The ranges of Tg, Tx and ΔTx are around 430–459, 467–497, and 30–46 K, respectively. The Mg49Y15Cu36 glassy powders exhibit the largest supercooled region of 46 K. The amorphization behavior of Mg61Y15Cu24 was examined in details. Amorphous phases gradually became dominant after 7.5 h of milling and fully amorphous powders formed at the end of milling. The thermal stability of Mg61Y15Cu24 glassy powders was similar to that of melt-spun Mg60Y15Cu25 amorphous alloys. Mg61Y15Cu24 bulk metallic glass with homogeneously embedded nanocrystalline precipitates was successfully prepared by vacuum hot pressing. It was found that the applied pressure during consolidation could enhance the thermal stability and prolong the existence of amorphous phase inside Mg61Y15Cu24 powders.