Rapidly quenched Mg65AlxCu25−xMM10 (MM: mischmetal) alloys

The ductility of the amorphous Mg–Cu–RE (RE: rare earths) alloys could be improved by means of the partial substitution of Cu atoms by Al ones, as can be inferred from the heterogeneous amorphous concept [1,2]. Instead of only one RE element, a solid solution of RE known as mischmetal (MM) was used. Rapidly quenched (RQ) samples (cooling rate >103 K s−1) of Mg65AlxCu25−xMM10 (0⩽x⩽25 at.%) alloys were obtained in a splat cooling device. The structure and the crystallisation process were observed by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Fractographic analysis was carried out by scanning electron microscopy (SEM) on the fracture surface of samples broken by hand bending. With increase of the Al concentration, we observed that both the glass forming ability (GFA) and the amorphous pre-peak (a-pre-peak) in the XRD pattern decreased; meanwhile the crystallisation temperature increased. On the other hand, the ductility of the 10 at.% Al alloy was improved and a vein pattern was observed in the fracture surfaces.