On the effect of Al on the formation of amorphous Mg-Al-Cu-Y alloys

The bulk amorphous alloy (Mg1-xAlx)(60)Cu30Y10 has been studied, in particular the influence of Al concentration on the glass forming ability and on the various transition temperatures. The amorphous single phase has been obtained for x up to 0.07 by casting into a wedge-shaped copper mold. The amorphous alloys were investigated by differential scannning calorimetry (DSC). All the specimens with x = 0 - 0.07 show a clear glass transition. The crystallization temperature decreases with increasing Al concentration, while the temperatures of the glass transition, melting and solidification change only slightly. The DSC measurements show that for Al contents below 0.05 the first exothermic peak which corresponds to crystallization, consists of two overlapping peaks. To clarify the origin of the splitting of the first exothermic peak, the crystallization process of Mg60Cu30Y10 alloy has also been studied by x-ray diffraction.