Shuffle-nanodomain regulated strain glass transition in Ti-24Nb-4Zr-8Sn alloy

Liang, Q and Wang, D and Zheng, Y and Zhao, S and Gao, Y and Hao, Y and Yang, R and Banerjee, D and Fraser, HL and Wang, Y (2020) Shuffle-nanodomain regulated strain glass transition in Ti-24Nb-4Zr-8Sn alloy. In: Acta Materialia, 186 . pp. 415-424.

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Abstract

The unprecedented properties of multi-functional metastable β-Ti alloys, including superelasticity over a wide temperature range, ultra-low modulus, and Invar and Elinvar anomalies, have attracted a great deal of attention. Persistent research efforts have been made towards the understanding of the origins of these unique properties. In this article we report a novel shuffle-nanodomain regulated strain glass transition in a metastable β-Ti alloy, Ti-24Nb-4Zr-8Sn (wt., Ti2448), which could be the dominant transformation pathway that offers these unique properties. Using the ex-situ aberration-corrected scanning transmission electron microscopy and in-situ cooling transmission electron microscopy, we find that randomly distributed 011�01¯1�β O� phase (orthorhombic, shuffle only) nanodomains embedded in the β phase (BCC) matrix at room temperature transform to α� phase (orthorhombic) with a continuous increase in the amount of 21¯1�1¯1¯1�β shear upon cooling or loading. Crystallographic analysis shows that the shuffle of the O� phase will restrain the twelve possible shears that transform a BCC lattice to α� martensite to only two. Thus, the randomly distributed O� nanodomains prevent the formation of long-range-ordered, self-accommodating transformation-strain domain patterns seen in normal martensitic transformations and suppress completely the sharp first-order, auto-catalytic and avalanche-like martensitic transformation into a high-order-like (continuous) strain glass transition. Such a continuous β � O� � α� strain glass transition has been confirmed by dynamic mechanical analysis, resistivity and differential scanning calorimetric measurement. This unique transition pathway allows us to offer new insights into the unique properties found in this alloy.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Acta Materialia Inc
Additional Information:	Copyright of this article belongs to Acta Materialia Inc
Keywords:	Elasticity; Glass; Glass transition; High resolution transmission electron microscopy; In situ processing; Martensitic transformations; Niobium alloys; Scanning electron microscopy; Tin alloys; Zircaloy, Aberration-corrected scanning transmission electron microscopies; Crystallographic analysis; Differential scanning calorimetric measurements; In-situ transmission electron microscopies; Strain glass transition; Superelasticity; Ti alloys; Transformation pathways, Titanium alloys
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	13 Feb 2020 11:37
Last Modified:	13 Feb 2020 11:37
URI:	http://eprints.iisc.ac.in/id/eprint/64508

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