Development of solidification microstructure in boron-modified alloy Ti-6Al-4V-0.1B

Roy, Shibayan and Suwas, Satyam and Tamirisakandala, S and Miracle, DB and Srinivasan, R (2011) Development of solidification microstructure in boron-modified alloy Ti-6Al-4V-0.1B. In: Acta Materialia, 59 (14). pp. 5494-5510.

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Abstract

Hypoeutectic boron addition (0.1 wt.%) to Ti-6Al-4V is known to cause significant refinement of the cast microstructure. In the present investigation, it has been observed that trace boron addition to Ti-6Al-4V alloy also ensures excellent microstructural homogeneity throughout the ingot. A subdued thermal gradient, related to the basic grain refinement mechanism by constitutional undercooling, persists during solidification for the boron-containing alloy and maintains equivalent beta grain growth kinetics at different locations in the ingot. The Ti-6Al-4V alloy shows relatively strong texture with preferred components (e.g. ingot axis parallel to[0 0 0 1] or [1 0 (1) over bar 0]) over the entire ingot and gradual transition of texture components along the radius. For Ti-6Al-4V-0.1B alloy, significant weakening characterizes both the high-temperature beta and room-temperature a texture. In addition to solidification factors that are responsible for weak beta texture development, microstructural differences due to boron addition, e.g. the absence of grain boundary alpha phase and presence of TiB particles, strongly affects the mechanism of beta -> alpha phase transformation and consequently weakens the alpha phase texture. Based on the understanding developed for the boron-modified alloy, a novel mechanism has been proposed for the microstructure and texture formation during solidification and phase transformation. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Elsevier science
Additional Information:	Copyright of this article belongs to Elsevier science.
Keywords:	Titanium alloy;Boron addition;Solidification;Microstructure; EBSD
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	15 Sep 2011 11:03
Last Modified:	15 Sep 2011 11:03
URI:	http://eprints.iisc.ac.in/id/eprint/40451

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