INVESTIGATION OF SUPERPLASTICITY BY THE IMPRESSION CREEP TECHNIQUE

Impression creep tests have been carried out on a Zn-22% Al eutectoid alloy in two heattreatment conditions, as a function of applied stress and at temperatures of ∼25 to 270° C. At small grain sizes (∼ 0.9 μm) and in the temperature range ∼ 180 to 270° C, the observed deformation response conforms to Regions I, II and III typical of superplastic behaviour. Furthermore, strain-rate index values determined for Region II fall in the range 0.44 to 0.51, consistent with superplasticity. It is concluded that the impression creep technique offers considerable potential for characterization of superplastic alloy systems on small specimen volumes. © 1990 Chapman and Hall Ltd.