The difference in devitrification paths in Al87Ni7Sm6 and Al87Ni7La6 amorphous alloys

This paper describes the crystallisation of Al87Ni7La6 and Al87Ni7Sm6 metallic glasses. The substitution of Sm for La in the alloy causes a variation in the transformation mode evidenced by the number of differential scanning calorimeter (DSC) peaks: two for the La containing alloy at low heating rates, than three at high heating rates, and three for the one with Sm. The glass transition becomes manifest for each alloys at a typical heating rate below which it is overlapped by the first crystallisation event due to precipitation of fine Al crystals in both materials. The Kissinger plot for Al87Ni7La6 is not strictly linear as a possible consequence of overlapping processes. The second and third transformations of both alloys produce a metastable intermediate and the equilibrium phases, respectively. The second crystallisation steps of Al87Ni7Sm6 and Al87Ni7La6 involve linear Kissinger plots. The crystallisation behaviour of the two alloys is compared with that of Al87Ni7Ce6 and Al87Ni7Nd6 which were earlier shown to present two and three transformations, respectively. (C) 2003 Elsevier B.V. All rights reserved.