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Title: Solute embrittlement of SiC

The energies and stresses associated with the decohesion of β-SiC in the presence of mobile Pd and Ag impurities are studied from first principles. Density functional theory calculations are parameterized with a generalized cohesive zone model and are analyzed within a thermodynamic framework that accounts for realistic boundary conditions in the presence of mobile impurities. We find that Pd impurities will embrittle SiC when Pd is in equilibrium with metallic Pd precipitates. Our thermodynamic analysis predicts that Pd embrittles SiC by substantially reducing the maximum stress of decohesion as a result of a phase transition between decohering planes involving an influx of Pd atoms. The methods presented in this work can be applied to study the thermodynamics of decohesion of SiC in other aggressive environments containing oxygen and water, for example, and yield environment dependent cohesive zone models for use in continuum approaches to study crack propagation and fracture.
Authors:
 [1] ;  [2]
  1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48103 (United States)
  2. Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)
Publication Date:
OSTI Identifier:
22305989
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BOUNDARY CONDITIONS; COMPUTERIZED SIMULATION; CRACK PROPAGATION; DENSITY FUNCTIONAL METHOD; EMBRITTLEMENT; EQUILIBRIUM; FRACTURES; IMPURITIES; OXYGEN; PALLADIUM ADDITIONS; PHASE TRANSFORMATIONS; PRECIPITATION; SILICON CARBIDES; SILVER ADDITIONS; SOLUTES; STRESSES; THERMODYNAMICS