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Title: Alternating brittle and ductile response of coherent twin boundaries in nanotwinned metals

Nanotwinned metals have opened exciting avenues for the design of high strength and high ductility materials. In this work, we investigate crack propagation along coherent twin boundaries in nanotwinned metals using molecular dynamics. Our simulations reveal that alternating twin boundaries exhibit intrinsic brittleness and ductility owing to the opposite crystallographic orientations of the adjoining twins. This is a startling consequence of the directional anisotropy of an atomically sharp crack along a twin boundary that favors cleavage in one direction and dislocation emission from the crack tip in the opposite direction. We further find that a blunt crack exhibits ductility in all cases albeit with very distinct deformation mechanisms and yield strength associated with intrinsically brittle and ductile coherent twin boundaries.
Authors:
;  [1]
  1. Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States)
Publication Date:
OSTI Identifier:
22402617
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANISOTROPY; BRITTLENESS; CRACK PROPAGATION; CRACKS; CRYSTALLOGRAPHY; DEFORMATION; DESIGN; DISLOCATIONS; DUCTILITY; EMISSION; MATERIALS; METALS; MOLECULAR DYNAMICS METHOD; ORIENTATION; SIMULATION; YIELD STRENGTH