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对7050铝合金进行固溶处理,随后在应变速率为1.0×10-4～1.0×10-1 s-1,温度为420℃及460℃的条件下进行拉伸测试。采用光学显微镜、扫描电镜及背散射技术对变形后的试样进行了检测。结果显示,在应变速率为1.0×10-1 s-1且温度为460℃时,铝合金具有最大的超塑性,伸长率达273%;在此变形条件下,塑性变形过程基本处于稳定状态,应力保持不变。微观组织从粗大晶粒变为双峰结构,并继续转变为接近均匀的细晶粒;随着超塑性应变的增加,动态复原过程从动态再结晶与动态回复转向完全动态再结晶。
7050 aluminum alloy solution treatment, followed by the strain rate of 1.0 × 10-4 ~ 1.0 × 10-1 s-1, the temperature of 420 ℃ and 460 ℃ under the conditions of tensile test. The deformed samples were examined by optical microscopy, scanning electron microscopy and backscattering techniques. The results show that the maximum superplasticity and elongation of the aluminum alloy reaches 273% at a strain rate of 1.0 × 10-1 s-1 and a temperature of 460 ℃. Under this deformation condition, the plastic deformation process is basically stable , The stress remains unchanged. The microstructure changed from coarse to bimodal structure and continued to transform into nearly uniform fine grains. With the increase of superplastic strain, the process of dynamic recovery turned from dynamic recrystallization and dynamic recovery to complete dynamic recrystallization.