Low temperature and high strain rate superplastic flow in structural ceramics induced by strong electric-field

High-strength structural ceramics with sub-micron grain sizes can exhibit superplasticity, but the superplasticity appears at high temperatures and low strain rates. Low temperature and high speed superplastic flow in structural ceramics was achieved by applying a strong electric field above a threshold value during deformation. The application of a direct-current field of 190 V. cm(-1) led to superplastic deformation in Y2O3-stabilized tetragonal ZrO2 polycrystal with a total tensile elongation of > 150% at 800 degrees C and an initial strain rate of 2 x 10(-3) S-1. The field-activated plasticity was attributed to highly-accelerated self-diffusion induced not only by temperature rise but also by a field effect. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.