Cu含量对喷射成形7055铝合金微观组织和力学性能的影响

Effects of Cu Content on Microstructure and Mechanical Properties of Spray Formed 7055 Aluminum Alloy

通过拉伸试验、冲击试验以及微观组织观察试验,分析降低Cu含量对喷射成形7055铝合金强度、断裂韧性和微观组织的影响。力学性能试验表明,7055铝合金中Cu的质量分数由2.55%降低到2.17%时,对其强度和伸长率影响不大,但Cu含量降低后合金的断裂韧性显著提高。微观组织分析表明,Cu含量降低前晶界上存在粗大的Al_7Cu_2Fe相,Cu含量降低后晶界上的粗大析出相明显减少;断口分析表明,Cu含量降低前拉伸断口中存在较多的Al_7Cu_2Fe第二相,Cu含量降低后Al_7Cu_2Fe第二相明显减少。

Tensile strength,fracture toughness and microstructure of spray formed 7055 aluminum were studied by tensile test,impact test and metallographic examination.The mechanical properties test showed that the mass fraction of Cu in 7055 aluminum alloy decreased from 2.55%to 2.17%,which had little influence on the strength and elongation.However,the fracture toughness increased significantly after the Cu content decreased.The microstructure analysis shows that there is a coarse phase in the grain boundary before the Cu content decreases.The energy spectrum analysis shows that the coarse phase is Al 7Cu 2Fe phase.After the Cu content is reduced,the precipitated phase at the grain boundary is significantly reduced.Fracture analysis shows that there are more second phases in the tensile fracture before the decrease of Cu content.Energy spectrum analysis shows that the second phase is Al 7Cu 2Fe phase,and the second phase is obviously reduced after Cu content is reduced.