New perspectives on the grain-size dependent yield strength of polycrystalline metals

We formulate the grain-size dependent strengthening of polycrystalline metals as a multiplicative decomposition of the coarse-grain strength a o and a function depending on the grain size d normalized by a characteristic coarse-grain length scale L = b(G/sigma(0)), where G is the shear modulus, and b the magnitude of the Burgers vector. We show that this formulation leads to a collapse of all experimental data analyzed, making experimental results across different materials comparable. This suggests that the grain-size dependent strengthening of several materials can be characterized by a single function with different materials distinguished only by their coarse-grain strength. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.