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Micromechanisms of fracture and strengthening in free-standing Pt-aluminide bond coats under tensile loading

Alam, Md Zafir and Kamat, SV and Jayaram, V and Das, DK (2014) Micromechanisms of fracture and strengthening in free-standing Pt-aluminide bond coats under tensile loading. In: ACTA MATERIALIA, 67 . pp. 278-296.

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Official URL: http://dx.doi.org/10.1016/j.actamat.2013.12.033

Abstract

Free-standing Pt-aluminide (PtAl) bond coats exhibit a linear stress strain response under tensile loading and undergo brittle cleavage fracture at temperatures below the brittle-to-ductile transition temperature (BDTT). Above the BDTT, these coatings show yielding and fail in a ductile manner. In this paper, the various micromechanisms affecting the tensile fracture stress (FS) below the BDTT and yield strength (YS) above the BDTT in a PtAl bond coat have been ascertained and quantified at various temperatures. The micromechanisms have been identified by carrying out microtensile testing of stand-alone PtAl coating specimens containing different levels of Pt at temperatures between room temperature and 1100 degrees C and correlation of the corresponding fracture mechanisms with the deformation substructure in the coating. An important aspect of the influence of Pt on the tensile behavior, slip characteristics, FS/YS and BDTT in the PtAl coating has also been examined. The addition of Pt enhances the FS of the coating by Pt solid solution strengthening and imparts a concomitant increase in fracture toughness and yet causes a significant increase in the BDTT of the coating. Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the PERGAMON-ELSEVIER SCIENCE LTD, ENGLAND
Keywords: Pt-aluminide bond coat; Tensile behavior; Fracture stress; Brittle-ductile transition; Strengthening mechanisms
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Id for Latest eprints
Date Deposited: 12 Jun 2014 08:53
Last Modified: 12 Jun 2014 08:53
URI: http://eprints.iisc.ac.in/id/eprint/49020

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