Microstructure and texture evolution in the tension of superplastic Al-6Cu-0.4Zr

The effect of tension at 450 °C with a strain rate of 10^-3 s^-1 on the microstructure and texture of a superplastic Al-6Cu-0.4Zr alloy has been investigated. The strain rate sensitivity index was essentially constant with strain, and therefore microstructure, at m (almost equal) 0.45. The texture was dominated by a component centred on {0 1 1}(left angle bracket)(square root)2 1 1(right angle bracket), which became weaker with deformation. The two variants of that texture allowed the identification of bands in the microstructure which acted as internal markers, and persisted to high strain. The texture and microstructure changes are not consistent with relative grain translation via boundary sliding, and a combination of rate-sensitive slip and dynamic grain growth is a better candidate to explain the behaviour of this material.