Superplasticity in Al-33Cu eutectic alloy in as extruded condition

Abstract

Experiments were carried out to determine the superplastic properties of the Al-33Cu eutectic alloy in an as extruded condition. It is shown that the stress-strain curves do not attain a steady state condition and, except at high strain rates greater than ∼10^-2 s^-1, the curves show strain hardening due to concurrent grain growth. There is a sigmoidal relationship between stress and strain rate, with a maximum strain rate sensitivity of ∼ 0•5 at intermediate strain rates in region 2 and a decrease in the strain rate sensitivity to ∼ 0•3 at low strain rates in region 1. The maximum elongation to failure in these experiments is ∼1400% at an initial strain rate of 6•7 × 10^-5 s^-1 and there is a decrease in the elongations to failure at both lower and higher strain rates. From detailed experimental measurements of grain growth, it is demonstrated by calculation that there is a genuine region 1 at low strain rates in this alloy in the as extruded condition.