T6处理对AZ91镁合金析出相β-Mg17Al12及断裂性能的影响
Effects of T6 Treatment on Precipitation of β-Mg17Al12 Phase and Fracture Properties of AZ91 Alloy
张菊梅1,2, 王志虎2, 蒋百灵2
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作者单位：(1. 西安科技大学 材料科学与工程学院, 陕西 西安 710054; 2. 西安理工大学 材料科学与工程学院, 陕西 西安 710048)
中文关键字：AZ91镁合金； T6处理； β-Mg17Al12相； 断裂性能
英文关键字：AZ91 alloy; T6 treatment; β-Mg17Al12 phase; fracture property
中文摘要：采用光学显微镜、场发射扫描电镜、X射线衍射及拉伸试验等研究了T6处理对铸态AZ91镁合金析出相β-Mg17Al12及断裂性能的影响。结果表明：分布在铸态AZ91镁合金晶界的粗大网状β-Mg17Al12相在T4热处理过程中几乎全部溶解，使合金的屈服强度下降，而抗拉强度和伸长率升高，断口形貌为具有一定塑性变形的解理特征；T6热处理后，合金组织中出现不连续析出与连续析出的β-Mg17Al12相，使合金的强度明显提高，而伸长率明显降低，其拉伸断裂方式以沿晶断裂为主。
英文摘要：The effects of T6 treatment on precipitation of β-Mg17Al12 phase and fracture properties of AZ91 alloy as-cast were studied by optical microscope, field emission scanning electron microscope, X-ray diffraction and tensile testing. The results show that the coarse and net β-Mg17Al12 phase distributed along the grain boundary is almost dissolved after T4 treatment. The average values of tensile strength and elongation enhance remarkably, but the yield strength decreases slightly after T4 treatment, the fractography demonstrates that the as-solution alloy's tensile fracture exhibites cleavage fracture. While after T6 treatment, both discontinuous and continuous precipitations of β-Mg17Al12 phase begin to form in the structure of AZ91 alloy. And the average values of tensile strength and yield strength are remarkably improved, however, the average elongation decreases. The fracture morphology of AZ91 alloy after T6 treatment is intergranular fracture behavior.