Abstract:

：The mechanical properties, conductivity, precipitation behavior and evolution process of elements and phases of spray formed 7075 alloy during retrogression are studied by tensile test, electric test, X-ray diffraction (XRD) analysis and lattice parameter test. The results show that the mechanical properties and conductivity could be effectively improved by the suitable retrogression temperature and time during the retrogression treatments. The tensile strength, yield strength, elongation and conductivity of the spray formed 7075 alloy after pre-aging at 120 ℃ for 16 h, retrogression at 200 ℃ for 8 min and re-aging at 120 ℃ for 24 h are 791 MPa, 736 MPa, 8.5% and 22.6 MS/m respectively. According to the XRD analysis and the accurate measurement of lattice parameter, the re-dissolution of elements and the precipitation of phases were able to be represented preferably. And due to optimizing and choosing the RRA treatment of 7075 alloy, the regularity of the re-dissolution and the precipitation of elements and phases were researched.

Key words: 7075 alloy, conductivity, retrogression and re-aging, strength, XRD, spray forming