Effect of stress orientation on microstructural evolution during creep of near-lamellar Ti-47Al-2Cr-2Nb

Babu, Prasath R and Karthikeyan, S (2013) Effect of stress orientation on microstructural evolution during creep of near-lamellar Ti-47Al-2Cr-2Nb. In: Materials Science and Engineering: A, 564 . pp. 218-231.

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Abstract

Microstructural evolution was studied in a near-lamellar two phase (alpha(2) + gamma) Ti-47Al-2Cr-2Nb alloy under high temperature creep and exposure conditions. The aim of this study was to probe the role of stress orientation, with respect to lamellar plates, on microstructural changes during primary creep. Creep testing was complemented with SEM and TEM based microstructural characterization. It was observed that retention of excess alpha(2) resulted in an unstable microstructure. Under stress and temperature, excess alpha(2) was lost and Cr-rich precipitates formed. Depending on stress orientation, the sequence of precipitates formed was different. alpha(2) loss was accompanied by formation of the non-equilibrium C14 Laves phase when lamellar plates were oriented parallel to the stress axis. In contrast, alpha(2) loss did not result in formation of the C14 phase in perpendicular samples. It was concluded that C14 formed preferentially in certain test orientations because of its effectiveness in relieving residual stresses in alpha(2) that arose from lattice misfit and modulus mismatch. (c) 2012 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:	γ-TiAl; Microstructural Stability; C14 Laves Phase; Creep; Misfit Stress; Elastic Mismatch
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	10 Apr 2013 07:00
Last Modified:	10 Apr 2013 07:00
URI:	http://eprints.iisc.ac.in/id/eprint/46312

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