Al含量对AZ系镁合金组织和力学性能的影响

Effects of Aluminum Content on the Microstructure and Mechanical Properties of AZ Magnesium Alloys

以AZ61、AZ71、AZ81镁合金作为研究对象,研究了Al含量对镁合金的组织结构与力学性能的影响。结果表明,随着Al含量的增加,镁合金微观组织中分布在α-Mg固溶体间的β-Mg17Al12金属间化合物数量增加,分布更加连续,当Al含量达到8%时,α-Mg初生相的连续性被割裂;合金力学性能变化与组织结构特征紧密相关,AZ71镁合金具有较好的室温力学性能,铸态时抗拉强度为211.63MPa,屈服强度为109.84MPa,伸长率为7.20%,固溶处理后抗拉强度达到235.98MPa,屈服强度达到122.12MPa,伸长率为14.72%;试样中脆性β-Mg17Al12金属间化合物的分布对于裂纹的扩展具有重要影响,铸态AZ系镁合金室温拉伸断口均表现为脆性断裂。

Effects of different Al contents on microstructure and mechanical properties of AZ series magnesium alloys were investigated. The results reveal that with increasing in Al content,numbers of Mg17Al12 phase distributed into α-Mg phase are increased with more continuous distribution in microstructure of Mg alloy,however,with 8% Al content,the α-Mg phase is isolated by the network Mg17Al12 phase. The mechanical properties of the alloy are closely related to the microstructure characteristics of α-Mg phase and Mg17Al12 phase. AZ71 magnesium alloy exhibits the best mechanical properties among three types of alloys. As-cast tensile strength,yield strength and elongation of the AZ71 alloy reach 211.63MPa,109.84MPa and 7.20%,respectively,and after solid solution treatment,tensile strength,yield strength and elongation reach 235.98MPa,122.12MPa and 14.72%,respectively. The distribution of brittle Mg17Al12 phase greatly affects crack propagation in tensile samples. The fracture morphologies of all AZ series alloys are characterized by brittle fracture.