超塑性变形对2A97铝锂合金微观组织和力学性能的影响  

Effect of superplastic deformation on microstructure and mechanical properties of 2A97 Al-Li alloy

作　　者：徐亚琪 叶凌英[1,2] 邹国童 李俊[1,2] 张翼飞 陈世杰 XU Yaqi;YE Lingying;ZOU Guotong;LI Jun;ZHANG Yifei;CHEN Shijie(School of Material Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous Metal Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]中南大学有色金属材料科学与工程教育部重点实验室,长沙410083

出　　处：《中国有色金属学报》2024年第9期2895-2907,共13页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(U21A20130)。

摘　　要：本文将2A97铝锂合金板材在430℃、2×10^(-3)s-1条件下进行超塑性拉伸实验,拉伸至不同真应变(ε=0.4、0.7、0.9、1.1)后对其进行室温拉伸测试和断口形貌分析,并结合电子背散射衍射(EBSD)和扫描电子显微镜(SEM)研究不同超塑性变形量对2A97铝锂合金微观组织的影响。结果表明:随着超塑性变形量的增加,小角度晶界通过动态再结晶转变为大角度晶界,晶粒形貌从条带状向等轴状演变;在真应变0~0.9阶段,平均位错密度由于动态再结晶作用从0.6×10^(13)m^(-2)下降至0.2×10^(13)m^(-2),但在真应变达到1.1时,由于由于协调晶界滑动平均位错密度反而上升至0.3×10^(13)m^(-2)。合金室温拉伸强度在真应变0~0.4阶段下降,在0.4~1.1阶段上升;而伸长率变化规律相反,由于在真应变0~0.4阶段,动态再结晶软化作用使强度下降;在真应变0.4~1.1阶段,第二相回溶增强固溶强化效果,同时晶界强化和析出强化综合作用使强度增加,而空洞面积分数从0.09%增加至0.47%,第二相粒子粗化,导致伸长率下降。2A97 Al-Li alloy was superplastic deformed to a series of true strains for 0.4,0.7,0.9 and 1.1 at 430℃with strain rate of 2×10^(-3)s-1.The room-temperature tensile test and fracture morphology analysis were carried out,and the effect of superplastic deformation on microstructure was studied by electron backscattering diffraction(EBSD)and scanning electron microscope(SEM).The results show that,with the increase of superplastic deformation,the small angle grain boundary changes to the large angle grain boundary through dynamic recrystallization,and the grain morphology evolves from strip to equal.At the true strain stage of 0-0.9,the average dislocation density decreases from 0.6×10^(13)m^(-2)to 0.2×10^(13)m^(-2)due to dynamic recrystallization,but increases to 0.3×10^(13)m^(-2)due to coordinating grain boundary slip when the true strain reaches to 1.1.The tensile strength decreases at true strain stage of 0-0.4,and increases at true strain stage of 0.4-1.1.The elongation variation is opposite significantly.The strength decreases because of the dynamic crystallization softening at true strain stage of 0-0.4;at the stage of 0.4-1.1,strength decreasing attributes to solid solution strengthening from second phases dissolution,grain boundary strengthening and precipitation strengthening.However,the area fraction of cavity increases from 0.09%to 0.47%,and second phases coarsen,leading to the decrease of elongation.

关 键 词：铝锂合金 超塑性变形 微观组织演变 位错 空洞 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]