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利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和力学万能试验机等手段研究了铸造Mg-6Zn-1.5Cu合金在不同状态下的组织,性能及断裂行为。结果表明,合金的铸态组织主要由α-Mg相,在晶界处呈连续或半连续分布的(α-Mg+MgZn_2+Mg_2Cu+CuMgZn)共晶相和晶内呈孤立的颗粒状相组成。合金在450℃固溶12~36h和180℃时效12~36h范围内,随着保温时间延长,固溶效果和时效强化效应逐渐增加;当固溶和时效时间超过28h后,固溶残余的共晶化合物和时效析出强化相均有粗化现象。合金在时效28h后获得了良好的组织,最大抗拉强度达265 MPa,最大伸长率达5.90%。铸态合金的断裂方式呈解理和沿晶断裂特征,时效处理后合金的断裂方式以沿晶和穿晶断裂混合模式存在。
The microstructure of the as-cast Mg-6Zn-1.5Cu alloy under different conditions was studied by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and mechanical universal testing machine. Performance and fracture behavior. The results show that the as-cast microstructure of the alloy consists mainly of α-Mg phase, (α-Mg + MgZn_2 + Mg_2Cu + CuMgZn) eutectic phase and continuous or semi-continuous distribution in the grain boundary, . The results show that the solid solution and aging strengthening effect gradually increase with the holding time prolonging for 12 ~ 36h at 180 ℃ and aging of 12 ~ 36h at 180 ℃. When the solid solution and aging time exceed 28h, Crystalline compounds and aging precipitation hardening have coarsening phenomenon. The alloy obtained good microstructure after 28h aging, the maximum tensile strength reached 265 MPa and the maximum elongation reached 5.90%. The fracture mode of as-cast alloy is cleavage and intergranular fracture, and the fracture mode of the alloy exists in the intergranular and transgranular fracture mode.