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利用XRD、SEM、TEM、EDS等测试方法对Mg-8.07Al-0.53Zn-1.36Nd镁合金微观组织结构进行表征与分析,并采用原位拉伸试验研究了合金显微组织对裂纹萌生及扩展行为的影响。结果表明:试验合金组织中主要包括α-Mg基体,β-Mg_(17)Al_(12),α+β共晶相,Al_(11)Nd_3针状相和Al_2Nd颗粒相。Al_2Nd存在孪晶结构,孪晶面为{11 1},Al_(11)Nd_3存在连续的凹凸界面结构。合金室温原位拉伸试验结果表明:裂纹主要在粗大的β-Mg_(17)Al_(12)相内部萌生,裂纹扩展方式包括沿晶扩展和穿晶扩展。裂纹穿晶扩展主要归因于沿晶界分布的Al_(11)Nd_3、Al_2Nd相与周围组织界面结合能力较强,Al_(11)Nd_3凹凸界面对基体与共晶组织的啮合作用显著。
The microstructure of Mg-8.07Al-0.53Zn-1.36Nd magnesium alloy was characterized and analyzed by XRD, SEM, TEM, EDS and other testing methods. In-situ tensile tests were conducted to study the effects of alloy microstructure on the initiation and propagation of cracks The impact of behavior. The results show that the microstructure of the alloy includes α-Mg matrix, β-Mg_ (17) Al_ (12), α + β eutectic phase, Al_ (11) Nd_3 acicular phase and Al_2Nd phase. The twin structure of Al_2Nd exists, the twin surface is {11 1}, and the Al_ (11) Nd_3 has continuous concavo-convex interface structure. The results of in-situ tensile tests at room temperature show that the cracks mainly occur in the coarse β-Mg_ (17) Al_ (12) phase, and the crack growth modes include intergranular expansion and transgranular expansion. The crack propagation is mainly attributed to the strong binding ability of Al 11 Nd 3 and Al 2 Nd phases along the grain boundaries and the interface between the Al 11 Nd 3 concavities and convexities and the surrounding tissues.