关键词: 稀土镁合金, 退火, 微观组织, 力学性能

Abstract: Effect of annealing process on microstructure and mechanical properties of a rare earth magnesium was investigated. The microstructure was characterized by using optical microscope and scanning electron microscope. The phase constitution and texture were analyzed by using X-ray diffractometer. The mechanical properties were tested by means of universal tensile testing machine. The results indicate that as the annealing temperature increases, the deformation twins gradually disappear, and the deformed grains undergo recovery and recrystallization. The average grain size gradually grows from 6.35 μm at 200 ℃ to 12.45 μm at 350 ℃, increased by 96.1%. Annealing time has a little effect on the grain size and texture constitution of the rare earth magnesium alloy. The Al₂Y phase is distributed within and at the grain boundaries of the matrix of the rare earth magnesium, which crystallizes in the liquid phase and precipitates in the solid phase, to inhibite the growth of crystalline grains during solidification, refine the initial grain size of the solidified state and pin the recrystallized grain boundaries during deformation and heat treatment processes to refine the grains. As the annealing temperature increases, the yield strength and tensile strength first decrease and then increase, and the elongation first increases and then decreases. After annealing at 300 ℃ for 60 min, the lowest yield strength and tensile strength of a rare earth magnesium alloy specimen can be obtained, with 158 MPa and 215 MPa, respectively, and the highest elongation is 16.0%.

Key words: rare earth magnesium alloy, annealing, microstructure, mechanical properties