Li对Al-3.5Cu-1.5Mg合金组织与性能的影响

摘要

The effect of Li on microstructures and properties of Al-3.5Cu-1.5Mg alloy was studied by optical microscopy (OM),transmission electron microscopy (TEM),scanning electron microscopy (SEM),Vickers hardness(HV)and electronic tensile test respectively.The results show that the addition of 1 ％ Li (mass fraction) translates the main precipitation phase S'(Al2CuMg) to S' (Al2CuMg) +δ'(Al3Li) in the alloy,which Cu/Mg atom ratio is about 1.Precipitate free zones (PFZs) are narrowed.Elastic modulus increases by 8GPa.The tensile strength is improved by 21MPa.However,the elongation of the alloy decreases from 20.3％ to 15.8％.The form of fracture morphology is changed from ductile fracture to ductile/brittle mixed fracture.%采用光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)、维氏硬度计和力学性能测试等方法研究了Li元素对Al-3.5Cu-1.5Mg合金微观结构及性能的影响.结果表明:在Cu/Mg原子比约为1的Al-3.5Cu-1.5Mg实验合金中,加入1％(质量分数)的Li元素,主要时效析出相由S’(Al2CuMg)转变为S’(Al2CuMg)+δ'(A13 Li),晶界无沉淀析出带(PFZ)窄化；弹性模量提高了8GPa,抗拉强度提高了21MPa,伸长率由20.3％降至15.8％,由韧性断口转变为韧/脆混合型断口.