时效工艺对Al-Zn-Mg-Cu-Zr-Er铝合金组织与耐腐蚀性影响

采用剥落腐蚀、极化曲线、电导率、力学性能测试和TEM显微组织分析，研究T6、T74及RRA时效工艺对Al-Zn-Mg-Cu-Zr-Er铝合金的组织、力学性能与耐腐蚀性的影响.结果表明:①T6态合金的强韧性最高（σ_b:663.5 MPa、σ_0.2:625.4 MPa、δ:12.46 %），但易腐蚀；与T6态合金相比，T74态合金（σ_b:640.2 MPa、σ_0.2:621.3 MPa、δ:11.34 %）的耐腐蚀性最好，但以牺牲强度为代价，而RRA态合金（σ_b:657.8 MPa、σ_0.2:628.8 MPa、δ:11.98 %）虽强韧性略低于T6态合金，但耐腐蚀性明显改善，综合性能优异.②合金的强度及耐腐蚀性分别与晶内η′析出相和晶界η析出相有关.晶内大量的η′析出相分布越均匀、弥散，尺寸越细小，合金的强度越高；晶界粗大的η析出相分布越离散，合金的耐腐蚀性越好.这与第一性原理计算的η′相与η相的理化性质相吻合. 

Influence of aging treatment on the microstructure and corrosion properties of Al-Zn-Mg-Cu-Zr-Er aluminum alloy

The influence of T6, T74, RRA aging treatment on microstructure, mechanical properties and corrosion properties of Al-Zn-Mg-Cu-Zr-Er aluminum alloy has been investigated by exfoliation corrosion, polarization curve, electrical conductivity, mechanical properties testing and TEM microstructure analysis. The results show that the alloy had the highest strength and toughness, but was susceptible to corrosion under T6 aging treatment(σ_b:663.5 Mpa; σ_0.2:625.4 MPa; δ:12.46 %). Compared with T6 aging treatment, the alloy had the best corrosion resistance with sacrificing the strength under T74 aging treatment(σ_b:640.2 MPa; σ_0.2:621.3 MPa; δ:11.34 %). Although the strength and toughness of RRA aging treatment(σ_b:657.8 MPa; σ_0.2:628.8 Mpa; δ:11.98 %)were slightly lower than T6 aging treatment, but it improved corrosion resistance obviously and had the excellent comprehensive performance. The strength and corrosion resistance of the alloy are related to matrix precipitates (η′) and grain boundary precipitates (η), respectively. A large amount of tiny η′ phase distributed more uniform and dispersed in matrix, the strength of the alloy is higher. The thick η phase distributed more discontinuous in the grain boundary, the corrosion resistance of the alloy is more beneficial, which is consistent with the physicochemical properties of η′ phase and η phase of the first principle.