Estimation of Maximum Solid Solubility in Mg–Hg Alloys by the Lever Rule

Abstract

The microstructures of Mg­Hg alloys with 1.1­2.9mass% Hg were investigated in this paper. Under the non-equilibrium solidification condition, the examined Mg­Hg alloys had a two-phase structure consisting of a solid solution phase and a spheroidal-graphite iron-like divorced eutectic. Eutectic i-Mg and eutectic Mg3Hg formed separately, so the proportion of eutectic Mg3Hg could be accurately measured. A method was proposed to estimate the maximum solid solubility of Hg in Mg under the non-equilibrium solidification condition by measuring the area fraction of Mg3Hg in metallographes. The maximum solid solubility of Mg­2.4mass% Hg was 0.81 and 0.69mass%, with cooling rates of 0.67 and 2.0K/s, respectively. The maximum solid solubility decreased as the cooling rate increased and increased as the Hg content increased. [doi:10.2320/matertrans.M2012272]