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Titolo:
Stress and shape evolution of irregularities in oxide films on elastic-plastic substrates due to thermal cycling and film growth
Autore:
Ambrico, JM; Begley, MR; Jordan, EH;
Indirizzi:
Univ Connecticut, Dept Mech Engn, Storrs, CT 06269 USA Univ Connecticut Storrs CT USA 06269 Dept Mech Engn, Storrs, CT 06269 USA
Titolo Testata:
ACTA MATERIALIA
fascicolo: 9, volume: 49, anno: 2001,
pagine: 1577 - 1588
SICI:
1359-6454(20010525)49:9<1577:SASEOI>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
BARRIER COATINGS;
Keywords:
mechanical properties-thermally activated process; oxidation; theory & modeling-defects; thin films;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
13
Recensione:
Indirizzi per estratti:
Indirizzo: Begley, MR Univ Connecticut, Dept Mech Engn, Storrs, CT 06269 USA Univ Connecticut Storrs CT USA 06269 ngn, Storrs, CT 06269 USA
Citazione:
J.M. Ambrico et al., "Stress and shape evolution of irregularities in oxide films on elastic-plastic substrates due to thermal cycling and film growth", ACT MATER, 49(9), 2001, pp. 1577-1588

Abstract

Initial geometric imperfections in oxide films on elastic-plastic substrates often develop local shape irregularities upon thermal cycling, even though the same system shows no such shape change under similar constant temperature exposure. This paper outlines a mechanics-based explanation of the evolution of such irregularities during thermal cycling, based on reversed plasticity in the material surrounding the irregularity and stress-dependent oxide film growth. idealized models consisting of spherical or cylindrical elastic shells embedded in an elastic-plastic matrix are used to identify regimes where thermal strains, cyclic reversed plasticity, geometry and oxide growth combine to promote rapid evolution of irregularities. The entirelyclosed-form solutions for stress and displacements during temperature cycling allow for quick evaluation of the role of various parameters, including: the temperature amplitude, size of the irregularity, oxide thickness, yield stress of the substrate and stress-dependent oxide growth strains. The usefulness of the solutions is illustrated by comparing two oxide film-growth scenarios with preliminary experimental results on a representative thermal barrier system that exhibits significant feature growth. The comparison demonstrates that oxide growth enhanced by tensile stresses created during reversed plastic deformation may be a significant factor in accounting for the large geometry changes observed in experiments. (C) 2001 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.

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Documento generato il 06/04/20 alle ore 09:43:13