Effects of pressure on structure and dynamics of metallic glass-forming liquid with miscibility gap

Abstract

The metallic liquid with miscibility gap has been widely explored recently because of the increasing plastic deformation ability of phase-separated metallic glass. However, the poor glass-forming ability limits its application as the structural materials due to the positive mixing enthalpy of the two elements. Since high pressure is in favor of the formation of the glass, the effect of pressure on the structural and dynamical heterogeneity of phase-separated Cu50Ag50 liquid is investigated by molecular dynamics simulation in the pressure range of 0–16 GPa. The results clearly show that the pressure promotes the formation of metallic glass by increasing the number of fivefold symmetry cluster W and dynamical relaxation time; meanwhile, the liquid–liquid phase separation is also enhanced, and the homogenous atom pairs show stronger interaction than heterogeneous atom pairs with increasing pressure. The dynamical heterogeneity is related to the formation of fivefold symmetry clusters. The lower growing rate of W at higher pressure with decreasing temperature corresponds to the slow increase in dynamical heterogeneity. The pressured glass with miscibility gap may act as a candidate glass with improved plastic formation ability. The results explore the structural and dynamical heterogeneity of phase-separated liquid at atomic level.