Creep ageing behaviour assisted by electropulsing under different stresses for Al−Cu−Li alloy  

Al−Cu−Li合金在不同应力下的电脉冲辅助蠕变时效行为

作　　者：Chang ZHOU Li-hua ZHAN He LI Xing ZHAO Fei CHEN Ming-hui HUANG 周畅;湛利华;李贺;赵兴;陈非;黄明辉(中南大学机电工程学院,长沙410083;中南大学高性能复杂制造国家重点实验室,长沙410083;中南大学轻合金研究院,长沙410083)

机构地区：[1]School of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China [2]State Key Laboratory of High-Performance Complex Manufacturing,Central South University,Changsha 410083,China [3]Light Alloys Research Institute,Central South University,Changsha 410083,China

出　　处：《Transactions of Nonferrous Metals Society of China》2021年第7期1916-1929,共14页中国有色金属学报（英文版）

基　　金：the financial supports by the National Key R&D Program of China(No.2017YFB0306300);the National Natural Science Foundation of China(Nos.51601060,51675538).

摘　　要：The influence of electropulsing on the creep behaviour,strength,and microstructure of an Al−Cu−Li alloy during creep ageing was investigated.Electropulsing assisted creep ageing(ECA)and conventional creep ageing(CCA)were carried out under various stress levels and time conditions.Applying electropulsing results in a noteworthy change of creep behaviour,including a variation in creep curves,an increased creep rate in early stage,and an improved creep strain.The ECA specimen experiences a shorter time to the peak strength,and an increase in elongation by~17.4% without loss of the peak-aged strength compared with CCA specimen.The ultrafine nano-size subgrains are observed to form under electropulsing,which can result in an increased creep strain by increasing grain-boundary sliding.The enhancement of both dislocation interactions and solute diffusion under electropulsing is considered as a primary cause of disappearance of a platform stage during early creep ageing.Some of T1 precipitates around the grain boundary are observed in the peak ECA sample,resulting in an occurrence of transgranular fracture,which is further responsible for an increased elongation of the ECA specimen.研究电脉冲对Al−Cu−Li合金蠕变时效行为、强度和显微组织的影响。在不同的应力和时间条件下,进行电脉冲辅助蠕变时效(ECA)和常规蠕变时效(CCA)实验。施加电脉冲可以显著改变合金的蠕变行为,包括蠕变曲线的变化、初期蠕变速率的增加和蠕变量的提高。ECA试样达到峰值强度的时间比CCA试样的短,在强度几乎不变的情况下,其伸长率提高约17.4%。在电脉冲作用下,晶粒细化导致形成超细纳米级亚晶粒,从而增加晶界滑动,提高蠕变量。电脉冲作用下位错相互作用和溶质原子扩散的增强被认为是蠕变早期平台阶段消失的主要原因。在峰时效ECA样品中观察到一些T1相在晶界附近析出,这将导致穿晶断裂的发生,进而提高试样的伸长率。

关 键 词：Al−Cu−Li alloy creep ageing ELECTROPULSING precipitation microstructure 

分 类 号：TG146.21[一般工业技术—材料科学与工程]