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研究了在脉冲电流作用下冷轧态２０９１ Ａｌ— Ｌｉ 合金的超塑形变． 脉冲电流的宽度为４０μｓ， 频率为４ Ｈｚ， 电流密度为１ ． ７８ ×１０３ Ａ／ｍ ｍ２ ． 在７７３ Ｋ 的温度下拉伸， 应变速率提高一倍， 流变应力有所降低． 采用前期形变通电的方法， 合金延伸率比常规超塑提高１２ ％ ． 超塑形变中不断产生动态再结晶． 在形变量小于４０ ％ 的第一阶段， 超塑形变机制可用 Ｂａｌｌ— Ｈｕｔｃｈｉｓｏｎ — Ｌａｎｇｄｏｎ 的晶界滑动—位错攀移的模型． 第二阶段（ 形变量４０ ％ ） ， 形变是在渗流分布状态的“损伤”晶界上滑动产生． 空位扩散在形变中起了重要调节作用
The superplastic deformation of cold-rolled 2091 Al-Li alloy under pulsed current was investigated. The width of the pulse current is 40μs, the frequency is 4 Hz and the current density is 1. 78 × 103 A / m m2. Tensile at a temperature of 773 K doubled the strain rate and reduced the flow stress. Adopting the method of pre-deformation electrification, the alloy elongation is increased by 12% compared with that of conventional superplasticizer. Superplastic deformation in the continuous dynamic recrystallization. In the first stage of deformation less than 40%, the model of Ball-Hutchison-Langdon grain boundary sliding-dislocation climbing can be used in the superplastic deformation mechanism. In the second stage (deformation 40%), deformation is caused by slip on the “damage” grain boundary of the seepage distribution. Gap diffusion plays an important regulatory role in deformation