Glass-forming ability, phase formation and mechanical properties of glass-forming Cu-Hf-Zr alloys

The influence of Hf additions on the glass-forming ability（GFA）,phase formation and mechanical properties of Cu;Hf;Zr;（x=2,5,10,20 at.%）alloys has been systematically investigated.We report on a distinct correlation between phase formation and GFA of Cu;Zr;-based alloys.Increasing additions of Hf reduce the thermal stability of the high-temperature B2Cu（Hf,Zr）phase,while the thermal stability of the corresponding undercooled melt is enhanced.The GFA of these alloy series gradually raises up to 10 at.%Hf,whereas at 20 at.%Hf,the GFA is drastically lowered,since the B2Cu（Hf,Zr）phase becomes unstable and the precipitation of the lowtemperature equilibrium phases is favoured.This interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass composites.These composites not only show appreciable macroscopic plastic strain,but also high yield strength.