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Study of fracture behaviour of bond coats on nickel superalloy by three-point bending of microbeams

Potnis, Prashant and Holtzinger, Jennifer and Das, Dipak and Jayaram, Vikram and Biswas, SK (2009) Study of fracture behaviour of bond coats on nickel superalloy by three-point bending of microbeams. In: Surface and Coatings Technology, 204 (5). pp. 586-592.

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Abstract

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 Ni3Al leads to gross bending and crack bifurcation.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier Science.
Keywords: Bond coat; Fracture toughness; Three-point bending
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 01 Dec 2009 05:08
Last Modified: 19 Sep 2010 05:52
URI: http://eprints.iisc.ernet.in/id/eprint/25002

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