Enthalpy recovery and its effect on homogeneous flow stress during supercooled liquid region for Ti40Zr25Ni8Cu9Be18 bulk metallic glass

The homogeneous flow exhibits strain softening for Ti40Zr25Ni8Cu9Be18 bulk metallic glass, which is related to increase in free volume concentration based on free volume model. When metallic glass is pre-annealed above Tg before deformation, the trend of strain softening becomes slow with pre-annealing time, indicating that the enthalpy recovery contributes to strain softening, because the enthalpy of metallic glass will recover towards equilibrium value above Tg, and leads to increase in free volume concentration. So the strain softening for Ti40Zr25Ni8Cu9Be18 bulk metallic glass is related to enthalpy recovery.

Research Highlights
► Enthalpy of Ti40Zr25Ni8Cu9Be18 BMG will recover towards equilibrium value when metallic glass is heated up above Tg.
► Enthalpy increases with time at first, then reaches steady state during enthalpy recovery.
► The free volume concentration will increase during homogeneous deformation, partly because of enthalpy recovery.
► The strain softening is related to enthalpy recovery during homogenous deformation.