瞬时电流和后续时效对7075铝合金力学性能和微观组织的影响  

Effects of Instantaneous Currents and Subsequent Aging Processes on Mechanics Properties and Microstructure of 7075 Aluminum Alloys

作　　者：崔晓辉 余卓行 肖昂 颜子钦 阳光 王瀚鹏 李瑞 CUI Xiaohui;YU Zhuoxing;XIAO Ang;YAN Ziqin;YANG Guang;WANG Hanpeng;LI Rui(Light Alloy Research Institute,Central South University,Changsha,410083;State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha,410083;Key Laboratory of Pico Electron Microscopy of Hainan Province,Hainan University,Haikou,570228;College of Mechanical and Electrical Engineering,Central South University,Changsha,410083)

机构地区：[1]中南大学轻合金研究院,长沙410083 [2]中南大学极端服役性能精准制造全国重点实验室,长沙410083 [3]海南大学海南省皮米电子显微学重点实验室,海口570228 [4]中南大学机电工程学院,长沙410083

出　　处：《中国机械工程》2024年第12期2139-2148,共10页China Mechanical Engineering

基　　金：国家自然科学基金(52275394);湖南省教育厅科研基金(22B0005);哈尔滨工业大学金属精密热加工国家级重点实验室开放课题(JCKYS2024603C007);极端服役性能精准制造全国重点实验室项目(ZZYJKT2024-05)。

摘　　要：提出了瞬时脉冲电流对铝合金超快固溶和后续时效强化的处理方案,采用宏微观实验手段分析了材料力学性能和微观组织演变规律。结果表明:随着放电电压的增大,预拉伸后7075铝合金材料屈服强度逐渐减小,但延伸率呈现“小幅度增大—减小—大幅度增大”的变化趋势。当脉冲电流峰值超过86 kA(对应的放电电压超过9 kV)时,材料力学拉伸曲线出现了波特文勒夏特利(Portevine Le Chatelier,PLC)效应。当脉冲电流峰值超过96 kA(对应的放电电压超过10 kV)时,试样的延伸率增大508.09%以上。微观表征发现,10 kV电压下材料中位错密度减小,η′相回溶到铝基体并形成过饱和固溶体,从而显著提高了材料塑性。结果表明,瞬时脉冲电流能够实现7075铝合金超快(<1 ms)固溶。对固溶后7075铝合金采用人工时效处理,材料硬度在人工时效21 h达到峰值,峰值时效处理后材料的硬度达到常规固溶淬火的98.69%。The ultrafast solution with pulsed instantaneous currents and subsequent aging strengthening of aluminum alloys were proposed and the mechanics properties and microstructure evolution of aluminum alloys were analyzed by means of macro and micro experiments.The results show that the yield strength of 7075 aluminum alloys decreases gradually with the increase of discharge voltages,but the elongation of 7075 aluminum alloys shows a trend of“small increase-decrease-large increase”.When the peak pulse currents exceed 86 kA(corresponding to a discharge voltage of more than 9 kV),the mechanics tensile curve of the material appears the Portevine Le Chatelier(PLC)effects.When the peak pulse currents exceed 96 kA(corresponding discharge voltage exceeds 10 kV),the elongation of the samples increases by more than 508.09%.It is found that the dislocation density in the materials decreases at 10 kV voltage,η′phase dissolves back into the aluminum matrix and forms susaturated solid solution,which significantly improves the plasticity of the materials.The results show that ultrafast(<1 ms)solution of 7075 aluminum alloys may be achieved by pulsed instantaneous currents.The strength of 7075 aluminum alloys reaches the peak after 21 hrs of artificial aging,and the hardness after peak aging reaches 98.69% of that of conventional solution quenching.

关 键 词：7075铝合金 脉冲电流处理 人工时效 微观结构 

分 类 号：TG391[金属学及工艺—金属压力加工]