微量锡对AA7085铝合金组织与性能的影响

利用金相显微镜、扫描电镜(SEM)、X射线衍射(XRD)、透射电镜(TEM)、维氏硬度计、断裂韧性性能测试等实验手段, 研究了添加0.1%Sn对AA7085铝合金组织与性能的影响。结果表明: 添加含量为0.1%的Sn能够细化AA7085合金的铸态组织, 形成了Mg₂Sn的第二相, 且该相在后续的热处理过程中能够保留下来; 添加Sn能够加快AA7085铝合金120 ℃下的时效初期的时效响应速度, 延缓峰值时效出现的时间, 同时使合金在过时效阶段保持较高的硬度和较低的硬度降低速率; 另外, 添加Sn的AA7085的抗拉强度和屈服强度分别为511 MPa和468 MPa, 比未添加Sn的合金的抗拉强度和屈服强度(504 MPa和441 MPa)均有所提高, 断裂韧性也从33.8 MPa·m^1/2提高到35.5 MPa·m^1/2, 表现出良好的综合力学性能。

Influences of Trace Sn on Microstructure and Property of AA7085 Aluminum Alloy

Influences of 0.1% Sn addition on the microstructure and mechanical properties of AA7085 alloys were investigated through fracture toughness testing and Vickers hardness testing combined with metallurgical microscope, scanning electron microscope (SEM), X-ray diffraction and transmission electron microscope (TEM). The results show that the addition of 0.1% Sn can made the as-cast structure of AA7085 alloy finer, forming Mg₂Sn second phase which will remain during the subsequent heat-treatment. Adding Sn can speed up the ageing response speed of AA7085 alloy at 120 ℃ in early aging, as well as delay the time to reach peak ageing, meanwhile, resulting in the alloy with a higher hardness and lower decreasing rate in hardness during the overaging stage. Furthermore, the tensile strength and yield strength of the AA7085-Sn alloy are 511 MPa and 468 MPa, respectively, higher than those of the alloy without Sn addition(504 MPa and 441 MPa). The fracture toughness of the AA7085-Sn alloy also increases from 33.8 MPa·m^1/2 to 35.5 MPa·m^1/2, exhibiting good comprehensive mechanical properties.