Effect of Zr on glass-forming ability and crystallization kinetics of Y 56Al 24Co 20 metallic glass

Abstract

The effect of the Zr addition on the glass-forming ability (GFA) and crystallization kinetics of Y 56Al 24Co 20 alloy has been investigated. It is found that Y 46Zr 10Al 24Co 20 has a reduced glass transition temperature as large as 0.626 at a heating rate of 20 K/min. Crystallization kinetic studies show that the activation energies derived from Kissinger equation for Y 46Zr 10Al 24Co 20 metallic glass of E g = 415.64 kJ/mol, E x = 279.74 kJ/mol and E p = 319.51 kJ/mol for glass transition, onset crystallization and crystallization peak, respectively, which are higher than those values for Y 56Al 24Co 20 one. The dependence of the glass transition on the heating rate was analyzed in terms of the Vogel–Fulcher–Tamman (VFT) equation. The glass-forming ability of the alloy was discussed based on the composition-dependent melting behavior, the reduced glass transition temperature, and the fragility parameter. It is shown that substitution of 10 at.% Zr for Y improves the glass-forming ability and the thermal stability of Y 56Al 24Co 20 alloy.