Developing superplasticity and a deformation mechanism map for the Zn-Al eutectoid alloy processed by high-pressure torsion

A Zn-22% Al eutectoid alloy was processed by high-pressure torsion (HPT) for 1.3 and 5 turns at room temperature to produce an ultrafine grain size of similar to 350 nm. Tensile testing at a temperature of 473 K gave excellent superplastic properties with elongations to failure up to a maximum of 1800% at an imposed strain rate of 1.0 x 10(-1) s(-1): this is within the range of high strain rate superplasticity and represents the highest elongation recorded to date for a specimen processed by HPT. It is shown that the experimental data are in excellent agreement with a deformation mechanism map constructed for a temperature of 473 K. (C) 2011 Elsevier B.V. All rights reserved.This work was supported by the National Science Foundation of the United States under Grant No. DMR-0855009