Si、Mg含量变化对Al-Mg-Si-Li合金组织和性能的影响

Effect of Si and Mg Level on Microstructure and Properties of Al-Mg-Si-Li Alloys

研究了Si、Mg含量变化对Al-Mg-Si-Li合金组织和性能的影响,分别采用光学显微镜、维氏硬度计、扫描电子显微镜、X-射线和拉力试验机研究合金的组织、性能和断口形貌。结果表明,随着Si含量增加,Al-Si-0.3Mg-1Li合金的组织组织中出现较多的初晶Si,而且越来越粗大,形状也变得不规则;加入Al-P中间合金可细化初晶Si,共晶化合物增多,Si质量分数为15%时,其抗拉强度和屈服强度均最大,分别可以达到255.0MPa、130.0MPa。Mg可以增加合金抗拉强度和延伸率,随着Mg含量的增加组织中α-Al相和初晶Si细化且数量减少,共晶组织增多,合金的力学性能提高。过量的Mg可以使合金出现鱼骨状组织Mg2Si,对力学性能不利。

The microstructure and properties of Al-Mg-Si-Li alloys were investigated.The microstructure was observed by optical microscopy,the phases were determined by X-rays,the mechamical properties were determined by tester,fracture morphology was observed by scanning electron microscopy.The result shows that the primary Si of alloy appears in the microstructure of the Al-Si-0.3Mg-1Li alloys with the increment of Si level.The more the Si content,the coarser and more irregular the primary Si becomes.Being modified by Al-P alloy,the primary Si is fine.Further,the tensile strength and the yield strength of the alloys are 255.0 MPa and 130.0 MPa with 15% Si.The tensile strength and the elongation of the Al-Si-Li alloys is improved with the addtion of magnesium.With the increment of Mg level,the α-Al and the primary Si phase are refined,the amount of primary Si decreases,the eutectic microstructure increases,so that the mechanical properties of the alloys increases.The mechanical properties of the alloys is poor as herringbone Mg2Si phase appears in the alloys by excessive Mg.