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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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
Publication:	ACTA MATERIALIA
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
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)
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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