Elevated temperature, micro-compression transient plasticity tests. on nanocrystalline Palladium-Gold: Probing activation parameters at the lower limit of crystallinity

In this study, we probe the activation parameters and time-dependent plastic behavior of a nano crystalline Palladium-Gold alloy by means of elevated temperature micropillar compression experiments. All tests were conducted on a stable, displacement-controlled in situ SEM indenter. A series of strain rate jump tests, where the strain rates were varied from 10(-4) s(-1) up to 10(-2) s(-1), allowed us to extract strain rate sensitivity and average activation volumes in the order of 8 b(3). Repeated load relaxation tests yielded lower activation volumes in the range of 4 b(3). From the variation of test temperatures up to 125 degrees C, we extracted an apparent activation energy of similar to 0.77 eV. The possible deformation mechanisms at such extremely small crystallite sizes are discussed within the framework of pertinent literature. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.