不同时效处理对Al-Zn-Mg-Cu合金热稳定性和腐蚀性能的影响  

Effect of different aging treatments on thermal stability and corrosion performance of Al-Zn-Mg-Cu alloy

作　　者：赵娟刚 李飞 罗钦文 桑建权 刘春泉 何舒旋 王贵婷 刘志义[2] ZHAO Juan-gang;LI Fei;LUO Qin-wen;SANG Jian-quan;LIU Chun-quan;HE Shu-xuan;WANG Gui-ting;LIU Zhi-yi(School of Materials Science and Engineering,Hunan Institute of Technology,Hengyang 421200,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China)

机构地区：[1]湖南工学院材料科学与工程学院,湖南衡阳421200 [2]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《材料热处理学报》2025年第1期11-21,共11页Transactions of Materials and Heat Treatment

基　　金：湖南省自然科学基金(2023JJ50114);湖南省应用特色学科材料科学与工程学科(湘教通〔2022〕351号);湖南省应用特色学科开放基金项目(KFB23008);2023年湖南省大学生创新创业训练计划项目(S202311528007);湖南工学院大学生创新训练中心入驻项目(2022EP16C)。

摘　　要：采用万能拉伸试验机、浸泡腐蚀试验和电化学测试等研究了经不同工艺时效处理(T6、四级时效、三级时效和T73)后Al-Zn-Mg-Cu合金的力学性能和耐腐蚀性能,采用扫描电镜和透射电镜观察了不同时效态合金的微观组织,并对相关机理进行了分析。结果表明:经100℃×24 h+170℃×4 h+水淬+自然时效×24 h+80℃×34 h四级时效处理后,合金具有最优的综合性能,抗拉强度为627 MPa,屈服强度为565 MPa,伸长率为10.9%;120℃热暴露500 h后合金的抗拉强度仅下降了4.94%,屈服强度仅下降了4.78%;四级时效处理后合金的自腐蚀电流密度为17.29μA·cm^(-2),自腐蚀电位为-730 mV,与T6时效处理的合金相比,耐腐蚀性能略有提高,但与三级时效和T73时效处理的合金相比有所降低,T73时效处理的合金耐腐蚀性能最好。该时效态合金具有优良的拉伸强度与热稳定性的原因在于,在回归处理之后加入的24 h自然时效期间,Mg原子与空位相结合形成了Mg-空位结合体,从而在再时效阶段析出了更多的G·P区强化相,最终提高了合金的强度。Mechanical properties and corrosion resistance of Al-Zn-Mg-Cu alloy after different aging treatments(T6,four-stage aging,three-stage aging and T73)were studied by means of universal tensile testing machine,immersion corrosion test and electrochemical test.Microstructure of the alloy in different aging states was observed using scanning electron microscopy and transmission electron microscopy,and the related mechanism was analyzed.The results show that after four-stage aging treatment at 100℃×24 h+170℃×4 h+water quenching+natural aging×24 h+80℃×34 h,the alloy has the best comprehensive properties,with the tensile strength of 627 MPa,the yield strength of 565 MPa,and the elongation of 10.9%.After exposure at 120℃for 500 h,the tensile strength of the alloy only decreases by 4.94%,and the yield strength only decreases by 4.78%.The self corrosion current density of the alloy after four-stage aging treatment is 17.29μA·cm^(-2),the self corrosion potential is-730 mV,compared with the alloy treated with T6 aging,the corrosion resistance of the alloy is slightly improved,but it is reduced compared with the alloy treated with three-stage aging and T73 aging,and the alloy treated with T73 aging has the best corrosion resistance.The reason why this aged alloy has excellent tensile strength and thermal stability is that during the natural aging for 24 h after the regression treatment,Mg atoms combine with vacancies to form Mg-vacancy complexes,thereby precipitating more G·P zone strengthening phases during the re-aging stage,ultimately improving the strength of the alloy.

关 键 词：AL-ZN-MG-CU合金 热稳定性 微观组织 G·P区 

分 类 号：TG146.2[一般工业技术—材料科学与工程]