热处理对镍合金化7075铝合金凝固组织结构及力学性能的影响

Effects of Heat Treatment on Solidification Microstructure and Mechanical Properties of Ni Alloying 7075 Aluminum Alloy

镍合金化7075铝合金展现出较好的抗热裂性能,为了探究该合金热处理调控技术,比较研究了热处理对该合金微观结构及力学性能的影响。结果表明,7075合金的凝固组织主要由初生相和晶间多相离异共晶组成。经固溶时效处理后,晶间的Al-Cu-Mg金属间化合物完全溶入基体合金,铸态试样中粗大的Al-Ni化合物也明显细化,分布更为分散。热处理后试样的综合力学性能均有明显提升,当7075铝合金中的Ni含量为0.6%时,平均抗拉强度较7075合金和Ni含量为1.2%的7075铝合金分别提高了14%和17%,表明晶间化合物结构调控是改善合金抗拉强度的重要因素。

Nickel alloying 7075 aluminum alloy exhibits superior thermal cracking resistance.In order to explore the heat treatment regulation technology of the as-cast alloys,the influence of heat treatment conditions on the microstructure and mechanical properties of the 7075 alloys were investigated comparatively.The results reveal that the solidification microstructure of the alloys is mainly composed of primaryα-Al phase and intergranular multi-phase divorced eutectic microstructure.The intergranular Al-Cu-Mg intermetallic compounds are completely dissolved into the matrix alloy after solid solution aging,where the coarse Al;Ni intermetallic compound in the as-cast specimens is also refined with dispersed distribution.After heat treatment,the comprehensive mechanical properties of the specimens are significantly improved,where the average tensile strength of 7075 aluminum alloy with 0.6%Ni content is 14%and 17%,higher than that of 7075 alloy and 7075 aluminum alloy with 1.2%Ni content,respectively,indicating that the microstructural control of intergranular compounds is the key factor to improving the tensile strength of the alloy.