On factors influencing the ductile-to-brittle transition in a bulk metallic glass

Raghavan, R and Murali, P and Ramamurty, U (2009) On factors influencing the ductile-to-brittle transition in a bulk metallic glass. In: Acta Materialia, 57 (11). pp. 3332-3340.

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Abstract

An experimental study to ascertain the ductile-to-brittle transition (DBT) in a bulk metallic glass (BMG) was conducted. Results of the impact toughness tests conducted at various temperatures on as-cast and structurally relaxed Zr-based BMG show a sharp DBT. The DBT temperature was found to be sensitive to the free-volume content in the alloy. Possible factors that result in the DBT were critically examined. It was found that the postulate of a critical free volume required for the amorphous alloy to exhibit good toughness cannot rationalize the experimental trends. Likewise, the Poisson's ratio-toughness correlations, which suggest a critical Poisson's ratio above which all glasses are tough, were found not to hold good. Viscoplasticity theories, developed using the concept of shear transformation zones and which describe the temperature and strain rate dependence of the crack-tip plasticity in BMGs, appear to be capable of capturing the essence of the experiments. Our results highlight the need for a more generalized theory to understand the origins of toughness in BMGs.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Elsevier Science.
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Metallic glass;Impact test;Toughness;Brittle-to-ductile transition;Free volume
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 Dec 2009 06:27
Last Modified:	19 Sep 2010 05:38
URI:	http://eprints.iisc.ac.in/id/eprint/21665

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