Glass-forming ability and crystallization of bulk metallic glass (HfxZr1−x)52.5Cu17.9Ni14.6Al10Ti5

We have produced a series of bulk metallic glasses of composition (Hf_xZr_1−x)_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ (with x=0-1) by an arc melting/suction casting method. The density of these alloys increases by nearly 67% with increasing Hf content from 6.65 g/cm³ (x=0) to 11.09 g/cm³ (x=1). Over the same composition range the glass-forming ability decreases, as demonstrated by the size of the largest amorphous ingots that can be cast without crystallization. Although both the glass transition temperature and the melting temperature increase linearly with increasing Hf content, the reduced glass transition temperature (T_g/T_m) decreases, from 0.64 (x=0) to 0.62 (x=1), which suggests that the `confusion principle' correlating increased glass-forming ability with increased number of components, does not apply in this case due to the chemical similarity between Zr and Hf. A different crystallization behavior is observed for Zr-based and Hf-based glasses. The final crystalline phases are CuZr₂ and Zr₂Ni for Zr-based alloys, and Al₁₆Hf₆Ni₇ and CuHf₂ for Hf-based alloys.