Influence of liquid temperature on the crystallization behavior in Zr-Al-Cu-Pd amorphous alloy

The glass transition temperature (T-g), crystallization temperature (T-x), peak temperature of crystallization exothermic reaction (T-p) and Delta T-x(= T-x - T-g) of an amorphous Zr60Al10Cu20Pd10 alloy were found to show a distinct increase with increasing liquid temperature (T-L). On the other hand, there are no appreciable changes in the; T-g, T-x, T-p and Delta T-x with T-L for an amorphous Zr60Al10Cu30 alloy. The crystallized structure consists of Zr2Cu + ZrPd + ZrPd2 + Zr2Al for the Zr-Al-Cu-Pd alloy and Zr2Cu + Zr2Al for the Zr-Al-Cu alloy. The absence of the T-L dependence for the latter ternary alloy indicates that the dissolution of their crystalline phases into the liquid phase by heating takes place easily, leading to the formation of a homogeneously mixed liquid phase. However, the ZrPd and ZrPd2 compounds have difficulty to dissolve into the liquid owing to the stronger bonding nature resulting from much larger negative heats of mixing as compared with Zr-Cu and Zr-Al pairs. The significant change in the thermal properties with T-L is attributed to the residual existence of the Zr-Pd pair.