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研究T4和T6热处理状态下高真空压铸Mg-8Gd-3Y-0.4Zr(质量分数,%)合金的微观组织、化合物含量、力学性能及断裂行为。铸态Mg-8Gd-3Y-0.4Zr合金微观组织主要由α-Mg和共晶Mg24(Gd,Y)5化合物组成。经固溶处理后,共晶化合物大量溶解于镁基体,合金主要含过饱和α-Mg及方块相。固溶合金中方块相的含量随固溶温度的升高而增大,力学性能也有所提高。根据微观组织结果,确定475°C,2 h为Mg-8Gd-3Y-0.4Zr合金最优固溶方案。合金的最佳屈服强度为222.1 MPa,延伸率可达15.4%。铸态,T4状态下和T6状态下合金的拉伸断裂模式为穿晶准解理断裂。
The microstructure, compound content, mechanical properties and fracture behavior of Mg-8Gd-3Y-0.4Zr (mass fraction,%) alloy under high vacuum die casting under T4 and T6 heat treatment were studied. The microstructure of as-cast Mg-8Gd-3Y-0.4Zr alloy is mainly composed of α-Mg and eutectic Mg24 (Gd, Y) 5 compounds. After solution treatment, a large number of eutectic compounds dissolved in the magnesium matrix, the alloy mainly contains supersaturated α-Mg and the square phase. The content of the martensite phase in the solution alloy increases with the increase of solution temperature, and the mechanical properties also increase. According to the results of microstructure, the optimal solution of Mg-8Gd-3Y-0.4Zr alloy was determined at 475 ° C for 2 h. The best yield strength of the alloy is 222.1 MPa and the elongation is up to 15.4%. Tensile fracture mode of as-cast, T4 and T6 alloys is transcrystalline quasi-cleavage fracture.