Unusual relation between glass-forming ability and thermal stability of high-entropy bulk metallic glasses

Abstract

It is generally accepted that good glass formers have a high thermal stability against crystallization upon heating. In this paper, we report an unusual relationship between thermal stability and glass-forming ability (GFA) for high-entropy bulk metallic glasses (HE-BMGs). As compared with their conventional counterparts in the same alloy system, the HE-BMGs have a lower energy barrier for atomic diffusion during undercooling, which facilitates crystallization and then reduces the GFA. Our results clearly demonstrate that the GFA of BMGs is governed by the kinetics of the undercooled liquid, whilst their thermal stability is controlled by atomic diffusion in the glass-transition regime.

Keywords

• High-entropy bulk metallic glasses
• thermal stability
• glass-forming ability
• viscosity
• fragility