时效析出对Al-Cu-Li合金疲劳性能的影响  

Effect of aging precipitation on fatigue property of Al-Cu-Li alloy

作　　者：刘梦 陶小玉[1] 李凯芳 李欢 陈钰 柏松 刘志义[2] Liu Meng;Tao Xiaoyu;Li Kaifang;Li Huan;Chen Yu;Bai Song;Liu Zhiyi(School of Materials and Chemical Engineering,Pingxiang University,Pingxiang Jiangxi 337055,China;School of Materials Science and Engineering,Central South University,Changsha Hunan 410083,China)

机构地区：[1]萍乡学院材料与化学工程学院,江西萍乡337055 [2]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《金属热处理》2024年第11期224-230,共7页Heat Treatment of Metals

基　　金：国家自然科学基金(52001175);江西省教育厅科学技术研究项目(GJJ191150);江西省大学生创新创业训练计划(S202310895016)。

摘　　要：通过室温拉伸、疲劳裂纹扩展速率测试、扫描电镜(SEM)和透射电镜(TEM)等手段研究了Al-Cu-Li合金在143℃时效不同时间后的微观组织及力学性能。结果表明,在时效25~35 h阶段,合金强度快速增加,表现出较强的时效响应;而继续时效至65 h,强度增加幅度较小并达到峰值。不同时效时间(25、35、65 h)下合金的主要析出相都为T_(1)相,时效25 h后合金中T_(1)相尺寸细小且存在少量δ′相,可动位错可以切过析出相从而发生可逆滑移,增加疲劳裂纹偏转效应以及裂纹闭合效应,疲劳裂纹扩展速率最低,表现出较高的裂纹扩展抗力。随着时效时间的延长,T_(1)相尺寸及数量密度都有所增加,疲劳裂纹扩展速率增大。时效65 h后合金中T_(1)相尺寸明显增大,可动位错只能绕过T_(1)相从而产生应力集中,疲劳裂纹扩展速率明显加快,疲劳性能最差。Microstructure and mechanical properties of the Al-Cu-Li alloy aged at 143℃for different time were studied by means of tensile test,fatigue crack propagation rate test,scanning electron microscope(SEM)and transmission electron microscope(TEM).The results show that the strength of the alloy increases rapidly and shows a strong aging response when aged for 25-35 h,while the strength increases slightly and reaches a peak when aged for 65 h.The main precipitates of the Al-Cu-Li alloy after aging at 143℃for 25,35 and 65 h are T_(1) phase.After aging for 25 h,T_(1) phases precipitate with fine size,accompanying with precipitation of small amounts ofδ′phase.The alloy aged for 25 h shows a low fatigue crack growth(FCG)rate because the movable dislocations can cut through precipitated phases and undergo reversible slip,increasing fatigue crack deflection and crack closure effects,showing higher crack propagation resistance.With the increase of aging time,the size and number density of T_(1) phase increase,and the FCG rate increases.After aging for 65 h,the size of T_(1) phase greatly increases,the moving dislocation can only bypass these large phase,resulting in stress concentration,thus the FCG rate increases obviously,the fatigue property of the alloy is the worst.

关 键 词：AL-CU-LI合金 疲劳裂纹扩展 T_1相 时效 

分 类 号：TG146.2[一般工业技术—材料科学与工程]