Al-Cu-Li合金超低温变形行为和微观机制  

Deformation behavior and micro mechanism of Al-Cu-Li alloy at cryogenic temperature

作　　者：张劲 祝春楠[1] 易幼平 汪成 ZHANG Jin;ZHU Chunnan;YI Youping;WANG Cheng(Institute of light alloys,Central South University,Changsha 410083,China;State Key Laboratory of High Performance and Complex Manufacturing,Central South University,Changsha 410083,China)

机构地区：[1]中南大学轻合金研究院,湖南长沙410083 [2]中南大学高性能复杂制造国家重点实验室,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2022年第7期2457-2466,共10页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2019YFA0708802)。

摘　　要：通过拉伸性能测试、断口扫描、电子背散射衍射(EBSD)和透射电镜(TEM)等表征方式,探究不同初始状态的Al-Cu-Li合金室温和超低温变形行为区别,探明超低温对不同状态的Al-Cu-Li合金力学性能和微观组织的影响机理。研究结果表明:在低温条件下,随着变形温度降低,退火态(O态)Al-Cu-Li合金的强度和塑性均显著提升,预变形+人工时效态(T8态)Al-Cu-Li合金的强度显著上升,但塑性几乎不变;温度降低抑制了O态和T8态合金的动态回复,使位错密度提高,加工硬化程度增大,从而合金强度提高;在超低温下,O态合金的晶粒内部更多地参与变形,整体变形更加协调、均匀,使得O态合金具有更高的塑性;T8态Al-Cu-Li合金晶内存在大量T1相,晶内胞状结构被钉扎,晶粒不易变形;超低温下T8态合金的变形模式没有发生改变,故塑性不提升。The deformation behavior of an Al-Cu-Li alloy in different states at room temperature and cryogenic temperature,and the influence mechanism of cryogenic temperature on mechanical properties and microstructure of Al-Cu-Li alloy in different states were investigated by means of tensile property test,fracture scanning,electron backscatter diffraction(EBSD)and transmission electron microscope(TEM).The results show that with the decrease of the deformation temperature,the strength and elongation of annealed(O-state)Al-Cu-Li alloys increase significantly,while the strength of pre-deformed+artificially aged(T8 state)Al-Cu-Li alloys increases significantly,but the plasticity is not nearly varied.The decrease of temperature inhibites the dynamic recovery of the alloys,which increases the dislocation density and the degree of work hardening,and thus improvs the strength of the alloys.At cryogenic temperatures,the internal grain structure of O-state alloy is more involved in the deformation and the overall deformation is more uniform,which causes the O-state alloy to have higher plasticity.Because there is a lot of T1 phase in the T8 state Al-Cu-Li alloy,the cellular structure in the crystal is pinned and the grains are difficult to deform.At cryogenic temperature,the deformation mode of T8 alloys will not change,and so the plasticity will not be improved.

关 键 词：AL-CU-LI合金 人工时效 超低温 位错密度 T1相 晶粒变形 

分 类 号：TG146.2[一般工业技术—材料科学与工程]