A new composition zone of bulk metallic glass formation in the Cu-Zr-Ti ternary system and its correlation with the eutectic reaction

A new composition region of bulk metallic glass formation, around Cu₅₂Zr₄₀Ti₈, was discovered in the Cu-Zr-Ti ternary system, for which monolithic bulk metallic glass rods of 4 mm in diameter can be fabricated using copper mold casting. The solidification of the Cu₅₂Zr₄₀Ti₈ deeply-undercooled liquid mainly undergoes a univariant eutectic reaction, (L → Cu₁₀Zr₇ + CuZr), even though this composition was predicted to be a ternary eutectic point (L → Cu₁₀Zr₇ + CuZr + Cu₂ZrTi) by CALPHAD calculations. With respect to the deep-eutectic reaction of (L → Cu₁₀Zr₇ + CuZr) in the Cu-Zr binary alloys, alloying of Ti has a significant effect on further stabilizing the liquid, as indicated as a drop of the univariant eutectic groove, limiting the coupled growth of two crystalline phases, hence increasing the glass-forming ability.