The superplastic behaviour of the Al-CuAl₂ eutectic during compressive deformation

Abstract

The compressive response of superplastic Al-CuAl₂ eutectic alloy has been experimentally evaluated. The deformation is viscous and requires an initial time interval for the onset of steady-state deformation. At all test temperatures the strain at which the steady state is reached is an increasing function of the strain rate. In the steady-state region, the observed stress is a linear function of the diameter-to-height ratio, d/h, so long as d/h is less than or approximately equal to 2.0. When d/h is >2.0, end effects introduce nonlinearity. Basic curves derived in compression agree very well with earlier results in tension. Activation-energy values are also reported and their equivocal nature explained. It is concluded that the superplastic Al-CuAl₂ eutectic alloy is isotropic in its response to compressive forces. Additional experiments reveal that the purity of raw materials does not have a significant effect on behaviour during superplastic compression.