Synthesis of copper-rich amorphous alloys by computational thermodynamics

Abstract

We have used thermodynamically calculated phase diagrams of Cu–Zr–Ti to identify two low-melting Cu-rich alloys denoted by A and B as bulk amorphous alloys where none were thought to exist. These alloys show greater stability of the glassy phase than previously discovered alloys in the same system, as evidenced by the critical casting diameter of 5mm. We also calculated a temperature-composition diagram for alloy A as a function of Y using an approximate thermodynamic description of Cu–Zr–Ti–Y. This diagram shows that the liquidus temperature of alloy A decreases with the addition of Y, reaches a minimum, and increases again. Our experiments indeed showed the glass-forming ability of A reaches a maximum diameter of 10mm when 2at.% Y was added and then decreases again. We thus propose that the thermodynamically calculated liquidus temperature is an excellent guide to synthesize bulkier glasses, which can be readily obtained from calculated phase diagrams.