Medium-range Order of Zr54Cu38Al8 Bulk Metallic Glass

ABSTRACTWe have previously reported, based on fluctuation electron microscopy (FEM) data, that Zr50Cu45Al5 bulk metallic glass (BMG) contains significant icosahedral and crystal-like medium-range order. Here, we report similar finding for Zr54Cu38Al8 BMG, which is a poorer glass former. Like Zr50Cu45Al5, Zr54Cu38Al8 contains icosahedral and crystal-like structures. In the as-cast state, the crystal-like peak in the FEM data is stronger than icosahedral-like peak. After annealing at 0.83Tg (573 K), the icosahedral-like peak increases, but, unlike Zr50Cu45Al5, the crystal-like peak does not decrease. This tendency toward stronger, more thermally stable crystal-like order may be associated with the poorer glass forming ability of Zr54Cu38Al8.