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通过力学性能和电导率测试、慢应变速率试验(SSRT)以及显微组织TEM分析,研究了不同时效制度对新型Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr合金力学及应力腐蚀性能的影响。结果表明,合金的力学性能和应力腐蚀性能与时效制度密切相关。T6状态下,晶内析出相弥散细小,晶界析出相呈连续分布,合金的强度最高,抗应力腐蚀性能最差;经T7双级过时效处理后,晶界析出相粗化呈离散分布,出现明显宽化的晶间无析出带,合金的抗应力腐蚀性能得到明显提高,但其强度损失较多。经三级时效处理后,合金的组织综合了T6态和T7态的优点,使合金既有高的强度又有良好的抗应力腐蚀性能,合金的极限抗拉强度、屈服强度、伸长率和电导率分别达到580,570 MPa,16.7%和23.3 MS.m-1。
The effects of different aging regimes on the mechanical and stress corrosion properties of the novel Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr alloy were studied by mechanical properties and conductivity tests, slow strain rate test (SSRT) and microstructure TEM analysis . The results show that the mechanical properties and stress corrosion resistance of the alloy are closely related to the aging system. In T6 state, the precipitation phase in the grain is small and the precipitate phase in the grain boundary is continuously distributed. The strength of the alloy is the highest and the stress corrosion resistance is the worst. After the T7 two-stage overaging treatment, There was no obvious precipitation of crystal grain precipitation between the alloy, the stress corrosion resistance has been significantly improved, but its loss of strength more. After three-stage aging treatment, the alloy structure combines the advantages of the T6 state and the T7 state, so that the alloy has both high strength and good stress corrosion resistance. The ultimate tensile strength, yield strength, elongation and Conductivity reached 580,570 MPa, 16.7% and 23.3 MS.m-1, respectively.