Mg含量及固溶处理对Al-Cu-Li-Sc-Zr合金组织及性能的影响

Effects of Mg Content and Solution Treatment on Microstructure and Properties of Al-Cu-Li-Sc-Zr Alloy

通过真空感应熔炼制备了不同Mg含量的Al-Cu-Li-Sc-Zr合金,采用OM、XRD、SEM、EDS分析研究Mg含量对合金组织性能的影响。结果表明,添加Mg后,合金中针状AlLi相逐渐减少,形成新的Al_(2)MgLi共晶相,合金晶粒尺寸不断降低,但Mg含量过高时,晶界处粗大共晶相不断增多,对合金力学性能不利。随着Mg含量增加,合金的强度呈现先升高后降低的趋势。此外,Mg对合金断裂方式有一定影响,导致合金塑性下降。固溶处理进一步提升了合金的硬度和抗拉强度,显著改善了合金的塑性,但由于强化相的溶解,合金屈服强度下降。当Mg含量为1%时,固溶态Al-Li合金具有较好的综合力学性能,硬度(HV)、抗拉强度、屈服强度、伸长率分别为131.1、432.7 MPa、267.4 MPa、7.62%。

Al-Cu-Li-Sc-Zr alloys with different Mg contents were prepared by vacuum induction melting. The effects of Mg content on the microstructure and properties of the alloy were investigated by OM, XRD, SEM and EDS. The results indicate that after Mg addition, the acicular AlLi phase in the alloy is decreased gradually with forming a new Al_(2)MgLi eutectic phase, and the grain size of the alloy is decreased continuously. However, when the Mg content is excessive, the coarse eutectic phase at the grain boundary is increased continuously, which is adverse to the mechanical properties of the alloy. With the increase of Mg content, the strength of alloy is increased firstly and then decreased. In addition, Mg has a certain effect on the fracture mode of the alloy, resulting in the decrease of the plasticity. The hardness and tensile strength of the alloy are further improved by solution treatment, which significantly enhance the plasticity, while the yield strength is decreased due to the dissolution of strengthening phase. When the addition of Mg is 1%, the Al-Li alloy in solid solution state exhibits desirable comprehensive mechanical properties, where the hardness, tensile strength, yield strength and elongation of the alloy reach up to 131.1 HV, 432.7 MPa, 267.4 MPa and 7.62%, respectively.