脉冲电流对1420铝锂合金超塑性及组织演变影响  

Superplasticity and Microstructure Evolution of 1420 Al-Li Alloy with Current Pulse

作　　者：张艳苓[1] 侯红亮[1] 王耀奇[1] Zhang Yanling;Hou Hongliang;Wang Yaoqi(Beifing Key Laboratory of Digital Plasticity Forming Technology and Equipment, Aeronautical Key Laboratory for Plastic Forming Technologies, Beijing Aeronautical Manufacturing Technology Research Institute, Metal Forming Tech- nology Research Department, Beijing 100024, China)

机构地区：[1]北京航空制造工程研究所金属成形技术研究室塑性成形技术航空科技重点实验室数字化塑性成形技术及装备北京市重点实验室,北京100024

出　　处：《稀有金属》2017年第12期1299-1304,共6页Chinese Journal of Rare Metals

基　　金：国家重点基础研究发展计划项目(2011CB012803);国家自然科学基金项目(51334006;51605458;51605458)资助

摘　　要：通过温度480℃、初始应变速率0.001 s^(-1)条件下单轴超塑拉伸试验,研究了脉冲电流对1420铝锂合金超塑性变形行为的影响,在此基础上,利用光学显微镜(OM),透射电镜(TEM),X射线衍射(XRD)等分析手段,研究了脉冲电流对1420铝锂合金超塑变形过程中的晶粒形貌及尺寸、位错形态及密度的影响规律,结果表明:脉冲电流提高了1420铝锂合金超塑变形性能,降低了变形抗力,与未加脉冲电流超塑拉伸实验结果相比,施加脉冲电流后超塑拉伸延伸率由160%提高到270%,提高了68%;峰值应力由14.3 MPa降到10.7 MPa,降低了25%。1420铝锂合金超塑变形过程中发生了动态再结晶,脉冲电流促进了再结晶的形核,使变形后的组织更加均匀、细小,相同应变条件下,施加脉冲电流超塑变形后的平均晶粒尺寸低于未加脉冲电流超塑拉伸;位错运动是1420铝锂合金超塑变形重要的变形协调机制,脉冲电流促进了位错运动、打开了晶内位错缠结,降低了相同变形条件下的位错密度,使变形协调更易于进行。The effects of electric current pulse on superplasticity of 1420 Al-Li alloy through uniaxial tensile tests at temperature of 480 ℃ and initial strain rate of 0. 001 s- 1 were studied. Meanwhile, grain morphology and the size, shape and density of dislocations were analyzed by optical microscope （OM）, transmission electron microscope （TEM）, X-ray diffraction （XRD） etc. The experimen- tal results showed that the superplasticity of 1420 Al-Li alloy was improved and the deformation resistance reduced with pulse current. Compared to superplastic tensile test results, the peak stress was decreased from 14.3 to 10.7 MPa and was reduced by 25% with the electropulse, while the elongation was increased from 160% to 270% and was increased by 68%. Dynamics recrystallization existed during superplastic tensile, and current pulse accelerated the nucleation of recrystallization, so that the deformation microstructure was more uniform and fine. Dislocation motion was an important deformation coordination mechanism, and current pulse promotes dislocation movement, avoiding dislocation tangle in grain, and increased the ability of superplasticity. Under the experiment condition, the average grain size and dislocation density of electro-superplastic were lower than superplastic deformation.

关 键 词：1420铝锂合金 电致超塑性 动态再结晶 位错运动 

分 类 号：TG146.21[一般工业技术—材料科学与工程]