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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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|
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