Effect of Heat Treatment on Microstructure and Mechanical Properties of Alloy Mg – 10% Gd – 3% Y – 0.6% Zr

Resumo

The microstructure, mechanical properties and fracture behavior of magnesium alloy Mg – 10% Gd – 3% Y – 0.6% Zr is studied in cast condition and after T4 and T6 treatments. It is shown that in cast condition the alloy contains an α-phase (a magnesium-base solid solution) and a Mg₂₄(Gd, Y)₅ eutectic phase. After the solution treatment the eutectic phase dissolves in the α-matrix containing cuboid particles of a phase enriched with gadolinium and yttrium. The hardness and the tensile strength criteria are used to determine the optimum treatment for the cast alloy, i.e., 8-h solution treatment at 500°C and 16-h aging at 220°C (T6). This mode of heat treatment provides the best mechanical properties.