Cu-based bulk metallic glasses designed by stability evaluations of liquid and amorphous phases

From the point of translation from liquid to amorphous phase, a new approach for composition design of bulk metallic glasses (BMGs) was suggested based on the stability estimations of liquid and amorphous phases. Gibbs free energy (ΔG) of liquid phase, which can be calculated approximately using mixing enthalpy (ΔHmix) and configuration entropy (Sconfig), was taken as a stability criterion of liquid phase. On the other hand, vacancy formation energy (ΔHh) was used to evaluate the stability of amorphous phase due to the linear relationship between ΔHh and crystallization temperature (Tx). Based on these two sides, new Cu-Zr-Nd bulk metallic glasses were designed and synthesized successfully by suction-casting into copper mold. Experimental results about glass-forming ability are consistent with the computational values, which not only proves the validity of the new approach for composition design but also shows the new BMG of Cu60.5Zr34Nd5.5 can be cast into amorphous alloys with 2 mm in diameter.