Study of fracture behaviour of bond coats on nickel superalloy by three-point bending of microbeams
A microbeam testing geometry is designed to study the variation in fracture toughness across a compositionally graded NiAl coating on a superalloy substrate. A bi-material analytical model of fracture is used to evaluate toughness by deconvoluting load–displacement data generated in a three-point be...
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Published in | Surface & coatings technology Vol. 204; no. 5; pp. 586 - 592 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier B.V
15.12.2009
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | A microbeam testing geometry is designed to study the variation in fracture toughness across a compositionally graded NiAl coating on a superalloy substrate. A bi-material analytical model of fracture is used to evaluate toughness by deconvoluting load–displacement data generated in a three-point bending test. It is shown that the surface layers of a diffusion bond coat can be much more brittle than the interior despite the fact that elastic modulus and hardness do not display significant variations. Such a gradient in toughness allows stable crack propagation in a test that would normally lead to unstable fracture in a homogeneous, brittle material. As the crack approaches the interface, plasticity due to the presence of Ni
3Al leads to gross bending and crack bifurcation. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0257-8972 1879-3347 |
DOI: | 10.1016/j.surfcoat.2009.08.038 |