Mechanism of failure in a free-standing Pt-aluminide bond coat during tensile testing at room temperature

Alam, Md Zafir and Srivathsa, B and Kamat, SV and Jayaram, V and Hazari, N and Das, DK (2010) Mechanism of failure in a free-standing Pt-aluminide bond coat during tensile testing at room temperature. In: Materials Science and Engineering A, 527 (3). pp. 842-848.

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Abstract

The room temperature (RT) tensile behaviour of a free-standing high activity Pt-aluminide bond coat has been evaluated by microtensile testing technique. The coating had a typical three-layer microstructure. The stress-strain plot for the free-standing coating was linear, indicating the coating to be brittle at RT. Different fracture features were observed across the coating layers, namely quasi-cleavage in the outer layer and inner interdiffusion zone, and cleavage in the intermediate layer. By employing interrupted tensile test and observing the cross-sectional microstructure of the tested specimens, it was determined that failure of the microtensile samples occurred by the initiation of a single crack in the intermediate layer of the coating and its subsequent inside-out propagation. Such a mechanism of failure has been explained in terms of the fracture features observed across the sample thickness. This mechanism of failure is consistent with fracture toughness values of the individual coating layers. (C) 2009 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Materials Science and Engineering A
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Bond coat; Pt-aluminide; Microtensile test; Failure mechanism; Crack nucleation and propagation; Fracture toughness
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	24 Feb 2010 05:04
Last Modified:	19 Jul 2011 12:06
URI:	http://eprints.iisc.ac.in/id/eprint/25829

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