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通过温度480℃、初始应变速率0.001s-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OM、TEM、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14.3MPa降到10.7MPa,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 effect of pulse current on the superplastic deformation behavior of 1420 Al-Li alloy was investigated by uniaxial superplastic tensile test at a temperature of 480 ℃ and an initial strain rate of 0.001 s-1. On this basis, OM, TEM and XRD were used The influence of pulse current on the morphology, size, dislocation morphology and density of 1420 Al-Li alloy during superplastic deformation was studied. The results show that the pulsed current increases the superplastic deformation properties of 1420 Al-Li alloy, Compared with the experimental results of superplastic tension without pulse current, the tensile elongation of superplasticity increased from 160% to 270%, increased by 68%; the peak stress decreased from 14.3MPa to 10.7 MPa, a decrease of 25%. The dynamic recrystallization occurred during the superplastic deformation of 1420 Al-Li alloy, and the pulse current promoted the nucleation of recrystallization, which made the deformed structure more uniform and fine. Under the same strain condition, the average crystal after pulse current superplastic deformation The grain size is lower than the superplastic stretching without pulse current. Dislocation movement is an important deformation coordination mechanism of superplastic deformation of 1420 Al-Li alloy. The pulse current promotes the dislocation movement, opens the intragranular dislocation entanglement and reduces the same Dislocation density under deformation conditions, the deformation coordination easier to carry out.