Grain boundary sliding revisited: Developments in sliding over four decades |
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Authors: | Terence G Langdon |
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Affiliation: | (1) Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453, USA |
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Abstract: | It is now recognized that grain boundary sliding (GBS) is often an important mode of deformation in polycrystalline materials.
This paper reviews the developments in GBS over the last four decades including the procedures available for estimating the
strain contributed by sliding to the total strain, ξ, and the division into Rachinger GBS in conventional creep and Lifshitz
GBS in diffusion creep. It is shown that Rachinger GBS occurs under two distinct conditions in conventional creep depending
upon whether the grain size, d, is larger or smaller than the equilibrium subgrain size, λ. A unified model is presented leading to separate rate equations
for Rachinger GBS in power-law creep and superplasticity. It is demonstrated that these two equations are in excellent agreement
with experimental observations. There are additional recent predictions, not fully resolved at the present time, concerning
the role of GBS in nanostructured materials. |
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