原子团簇尺寸对Al-Cu-Mg合金疲劳过程中滑移带形成及裂纹扩展行为的影响  

Effect of atomic cluster sizes on the formation of slip bands in the fatigue process and the crack propagation behavior of an Al-Cu-Mg alloy

作　　者：刘梦 秦梦黎[1] 柏松 刘志义[2] LIU Meng;QIN Mengli;BAI Song;LIU Zhiyi(School of Materials and Chemical Engineering,Pingxiang University,Pingxiang 337055,Jiangxi,China;School of Materials Science and Engineering,Central South University,Changsha 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,长沙410083

出　　处：《有色金属科学与工程》2023年第4期501-510,共10页Nonferrous Metals Science and Engineering

基　　金：江西省教育厅科学技术研究资助项目(GJJ191150);国家自然科学基金资助项目(52001175)。

摘　　要：通过透射电镜(TEM)、原子探针(APT)等分析手段,研究了不同时效态Al-Cu-Mg合金中原子团簇对疲劳裂纹扩展行为的影响。结果表明:自然时效态试样只含有小尺寸原子团簇(<100个原子),而170℃人工时效态试样出现大尺寸原子团簇(>100个原子),且随着时效时间的延长,大尺寸原子团簇逐渐增多,并在170℃/8 h态开始析出少量S′相。小尺寸原子团簇对位错滑移的阻碍作用较小,在裂纹扩展过程中形成了较多的滑移带,裂纹沿滑移带扩展,表现出较高的裂纹扩展速率;随着团簇尺寸的增大,延缓了Al-Cu-Mg合金在疲劳过程中的溶解和强化效应的衰减,限制了裂纹前端滑移带的形成,显著降低了裂纹扩展速率;S′相的析出阻止了位错往复滑移并减少了裂纹闭合效应,表现出较高的疲劳裂纹扩展速率。170℃/1 h态合金中大尺寸原子团簇数量密度较高,且没有析出S’相,因此具有较优的抗疲劳裂纹扩展性能。The effect of atomic clusters in Al-Cu-Mg alloys with various aging conditions on the fatigue crack propagation behavior was investigated using transmission electron microscopy(TEM),atom probe tomography(APT),scanning electron microscopy(SEM)and fatigue testing.The results showed that there were small-sized atomic clusters(<100 atoms)in the naturally aged samples while the larger ones(>100 atoms)occurred in the artificially aged samples at 170℃.The number density of larger atomic clusters(>100 atoms)increased gradually with the artificial aging time at 170℃,and S'phases began to form after aging at 170℃ for 8 h.The obstruction of dislocation slip by small clusters was limited.Thus,the fatigue crack mostly propagated along the slip band with a high propagation rate.The large clusters were harder to dissolve during cycle deformation,thus reducing the cyclic softening effect and enhancing the FCP resistance.The moving dislocations likely bypassed the S'phase,resulting in a lack of plane reversible slip and crack closure effects and inducing a high propagation rate.Therefore,the 170℃/1 h sample exhibited the best fatigue crack growth resistance due to the higher number density of large atomic clusters and the absence of the S'phase.

关 键 词：AL-CU-MG合金 疲劳裂纹扩展 滑移带 原子团簇 

分 类 号：TG146.2[一般工业技术—材料科学与工程]