Rapidly quenched Mg65AlxCU25-xMM10 (MM : mischmetal) alloys

The ductility of the amorphous Mg-Cu-RE (RE: rare earths) alloys could be i mproved by means of the partial substitution of Cu atoms by Al ones, as can be interred from the heterogeneous amorphous concept [1,2]. Instead of onl y one RE element, a solid solution of RE known as mischmetal (MM) was used. Rapidly quenched (RQ) samples (cooling rate > 10(3) K s(-1)) of Mg65AlxCu2 5-xMM10 (0 less than or equal to x less than or equal to 25 at.%) alloys we re obtained in a splat cooling device. The structure and the crystallisatio n process were observed by means of X-ray diffraction (XRD) and differentia l scanning calorimetry (DSC). Fractographic analysis was carried out by sca nning electron microscopy (SEM) on the fracture surface of samples broken b y hand bending. With increase of the Al concentration, we observed that bot h the glass forming ability (GFA) and the amorphous pre-peak (a-pre-peak) i n the XRD pattern decreased; meanwhile the crystallisation temperature incr eased. On the other hand, the ductility of the 10 at.% Al alloy was improve d and a vein pattern was observed in the fracture surfaces. (C) 2001 Elsevi er Science B.V. All rights reserved.