SYNTHESIS AND CHARACTERIZATION OF Mg-In ALLOYS (17.47% AT. AND 38.84% AT.) PREPARED BY MECHANICAL ALLOYING

Abstract

We synthesized two Mg-In alloys, namely, Mg 50% In (17.47% at. In) and Mg 75% In (38.84% at. In) by subjecting high purity Mg and In powders to mechanical alloying. The synthesis was followed in each case by X-ray diffraction (XRD), which allowed for the identification of a series of Mg-In metastable phases that occurred during the alloying process. The invariability of the diffraction patterns made it possible for the grinding time to be set at 10 hours, phases In0.144 Mg1.856 and In0.212 Mg 1.788 and phases InMg and InMg3 having the greatest presence in the Mg 17.47% at. In and Mg 38.84% at. In alloys, respectively. Samples thermally annealed at 300 and 400 ºC were studied by differential scanning calorimetry (DSC) and electrical resistivity (Dr). DSC measurements showed a series of endothermal phases according to what is established in the phase diagram of the Mg-In system. A kinetic analysis of the first reactions in both alloys after annealing at 300 ºC evinced that they occurred by indium diffusion in the Mg matrix. When the annealing was at 400 ºC, however, above the solubility limit of both b1 in the case of Mg 17.47% at. In; and b2 in that of Mg 38.84 % at In, reactions revealed low activation energy, mainly due in the first case to the migration of In atoms in the Mg solid solution, and to the order-disorder transition effects in the second. This behavior was ratified by Ap measurements