热处理对压铸Mg-8Gd-3Y-0.5Zr合金组织性能的影响

采用气体保护法制备Mg-8Gd-3Y-0.5Zr(GW83K)合金,并冷模压铸成拉伸试样。通过光学显微镜、扫描电镜观察及力学性能测试等分析合金压铸态和不同热处理状态下的显微组织及力学性能。结果表明:冷模压铸GW83K合金经热处理后,其力学性能较压铸态均有所提高,尤其是经低温短时固溶处理(T4)后的合金,其晶粒度变化不大,组织比较均匀,片层状的共晶体消失,第二相以不连续的棒状或粒状分布于晶界处。GW83K-T4合金的室温拉伸性能可达到σb=261.7MPa,σs=240.8MPa,δ5=6.0%,比压铸态合金分别提高了21%,28.4%和30.4%,且该合金具有较好高温力学性能。

Effects of Heat Treatment on Microstructure and Mechanical Properties of Die-Cast Mg-8Gd-3Y-0.5Zr Magnesium Alloy

Mg-8Gd-3Y-0.5Zr(GW83K) alloys were prepared by means of the atmosphere protection method and then chamber die cast into tensile samples with cold mould. The microstructures and mechanical properties of alloys in die-cast state and different heat treatment states were investigated by optical microscopy, scanning electron microscopy and mechanical property testing. The results show that the mechanical properties of the cold-mould die-cast GW83K alloys after heat treatment are improved. In particular, the die-cast GW83K alloy after short-time low-temperature solid solution treatment (T4) has a little variation in grain size and more uniform microstructure, lamellar eutectic disappears and the second phases distribute in the grain boundary in discontinuous rod shape or granule shape. Due to microstructure improvement of GW83K-T4 alloy, the mechanical properties of the alloy at room temperature are improved such as: σ_b=261.7 MPa,σ_s=240.8 MPa and δ_s=6.0%, which are increased by 21%, 28.4% and 30.4% compared with those of die-cast GW83K alloy respectively, and GW83K-T4 alloy has better elevated temperature mechanical properties.