Understanding the glass-forming ability of bulk metallic glasses

Bulk metallic glasses (BMGs) exhibit remarkable properties such as metal-like strength and plastic-like processability. To design BMGs with multifunctional properties, a key first step is to predict the glass-forming ability (GFA) of alloys. Despite decades of research, predictions of the GFA of alloys remains a major challenge. There have been experimental and simulation studies suggesting that alloys with a large variation in atomic sizes and mismatching crystal phases of the constituent elements tend to have better GFA. To better understand the physical features that control GFA, we calculate the GFA for six binary metallic alloys (that are composed of Ni, Cu, Al, and Mg) modeled using a range of interaction potentials, including Lennard-Jones (LJ), patchy-particle, and current embedded atom method (EAM) potentials, and compare the results to those from co-sputtering experiments. We find that the LJ and EAM potentials have difficulty capturing the GFA for many of the binary alloys. In contrast, we can recapitulate the crystal phase behavior and the GFA over the full range of concentrations for all six binary alloys using the patchy-particle model.