Effect of Zr on glass-forming ability and crystallization kinetics of Y56Al24Co20 metallic glass

The effect of the Zr addition on the glass-forming ability (GFA) and crystallization kinetics of Y56Al24Co20 alloy has been investigated. It is found that Y46Zr10Al24Co20 has a reduced glass transition temperature as large as 0.626 at a heating rate of 20K/min. Crystallization kinetic studies show that the activation energies derived from Kissinger equation for Y(46)Z(10)Al(24)Co(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 Y56Al24Co20 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 Y56Al24Co20 alloy. (c) 2007 Elsevier B.V. All rights reserved.