Conjugated precipitation of twin-related α and Ti2Cu phases in a Ti-25V-3Cu alloy

H. P. Ng; P. Nandwana; A. Devaraj; M. Samblanet; S. Nag; P. N.H. Nakashima; S. Meher; C. J. Bettles; M. A. Gibson; H. L. Fraser; B. C. Muddle; R. Banerjee

doi:10.1016/j.actamat.2014.10.053

Conjugated precipitation of twin-related α and Ti₂Cu phases in a Ti-25V-3Cu alloy

H. P. Ng, P. Nandwana, A. Devaraj, M. Samblanet, S. Nag, P. N.H. Nakashima, S. Meher, C. J. Bettles, M. A. Gibson, H. L. Fraser, B. C. Muddle, R. Banerjee

Research output: Contribution to journal › Article › peer-review

36 Scopus citations

Abstract

The formation of conjugated precipitates in a ternary Ti-25V-3Cu (wt.%) (Ti-24.4V-2.3Cu (at.%)) alloy subjected to isothermal aging at 500 °C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal α phase and body-centered-tetragonal (bct) Ti₂Cu intermetallic compound. These precipitates are composed of two geometrically symmetrical components, which are verified by transmission electron microscopy (TEM) to be twin-related variants of α and Ti₂Cu phases. Atomic-level characterizations incorporating high-resolution TEM and atom probe tomography were used to investigate the early-stage nucleation process of the precipitates. The results reveal that precipitation occurs heterogeneously on plate-like (or disc-like) metastable Cu-enriched GP zones that preferentially inhabit {1 1 0}_β planes. Crystallographic orientation analyses suggest that the Ti₂Cu phase is related to the matrix via a definite orientation relationship of (_01¯3)Ti2_Cu∥(_011)β and [₁₀₀]Ti₂Cu∥[_100]β, while the growth of the α phase is governed by the Potter's OR such that (_11¯01)α∥(_011)β and [_112¯0]α∥[_11¯1]β. (_01¯3)Ti₂Cu and (_11¯01)α are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated α and Ti₂Cu phases attain a nearly perfect lattice correspondence along certain crystallographic planes, which results in a low interfacial energy configuration and favours the co-development of these phases.

Original language	English
Pages (from-to)	457-471
Number of pages	15
Journal	Acta Materialia
Volume	84
DOIs	https://doi.org/10.1016/j.actamat.2014.10.053
State	Published - Feb 1 2015
Externally published	Yes

Funding

This work was supported in part by the Australian Research Council, and in part by the U.S. National Science Foundation, Division of Materials Research. One of the authors, P.N.H. Nakashima would also like to acknowledge and ARC for Future Fellowship funding ( FT110100427 ) for part of this work. The authors would like to gratefully acknowledge the use of facilities at the Center for Advanced Research and Technology (CART) at the University of North Texas. The authors acknowledge use of facilities within the Monash Centre for Electron Microscopy. This research used equipment funded by Australian Research Council grant LE0454166 .

Funders	Funder number
National Science Foundation
Division of Materials Research
Australian Research Council	FT110100427, LE0454166

Keywords

Atom probe tomography
Precipitation
TiCu phase
Transmission electron microscopy
β-Titanium alloy

Access to Document

10.1016/j.actamat.2014.10.053

Cite this

@article{520c1cd29c4f48b2948a613623f7e39b,

title = "Conjugated precipitation of twin-related α and Ti2Cu phases in a Ti-25V-3Cu alloy",

abstract = "The formation of conjugated precipitates in a ternary Ti-25V-3Cu (wt.%) (Ti-24.4V-2.3Cu (at.%)) alloy subjected to isothermal aging at 500 °C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal α phase and body-centered-tetragonal (bct) Ti2Cu intermetallic compound. These precipitates are composed of two geometrically symmetrical components, which are verified by transmission electron microscopy (TEM) to be twin-related variants of α and Ti2Cu phases. Atomic-level characterizations incorporating high-resolution TEM and atom probe tomography were used to investigate the early-stage nucleation process of the precipitates. The results reveal that precipitation occurs heterogeneously on plate-like (or disc-like) metastable Cu-enriched GP zones that preferentially inhabit {1 1 0}β planes. Crystallographic orientation analyses suggest that the Ti2Cu phase is related to the matrix via a definite orientation relationship of (01¯3)Ti2Cu∥(011)β and [100]Ti2Cu∥[100]β, while the growth of the α phase is governed by the Potter's OR such that (11¯01)α∥(011)β and [112¯0]α∥[11¯1]β. (01¯3)Ti2Cu and (11¯01)α are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated α and Ti2Cu phases attain a nearly perfect lattice correspondence along certain crystallographic planes, which results in a low interfacial energy configuration and favours the co-development of these phases.",

keywords = "Atom probe tomography, Precipitation, TiCu phase, Transmission electron microscopy, β-Titanium alloy",

author = "Ng, {H. P.} and P. Nandwana and A. Devaraj and M. Samblanet and S. Nag and Nakashima, {P. N.H.} and S. Meher and Bettles, {C. J.} and Gibson, {M. A.} and Fraser, {H. L.} and Muddle, {B. C.} and R. Banerjee",

note = "Publisher Copyright: {\textcopyright} 2014 Acta Materialia Inc.",

year = "2015",

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doi = "10.1016/j.actamat.2014.10.053",

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TY - JOUR

T1 - Conjugated precipitation of twin-related α and Ti2Cu phases in a Ti-25V-3Cu alloy

AU - Ng, H. P.

AU - Nandwana, P.

AU - Devaraj, A.

AU - Samblanet, M.

AU - Nag, S.

AU - Nakashima, P. N.H.

AU - Meher, S.

AU - Bettles, C. J.

AU - Gibson, M. A.

AU - Fraser, H. L.

AU - Muddle, B. C.

AU - Banerjee, R.

PY - 2015/2/1

Y1 - 2015/2/1

N2 - The formation of conjugated precipitates in a ternary Ti-25V-3Cu (wt.%) (Ti-24.4V-2.3Cu (at.%)) alloy subjected to isothermal aging at 500 °C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal α phase and body-centered-tetragonal (bct) Ti2Cu intermetallic compound. These precipitates are composed of two geometrically symmetrical components, which are verified by transmission electron microscopy (TEM) to be twin-related variants of α and Ti2Cu phases. Atomic-level characterizations incorporating high-resolution TEM and atom probe tomography were used to investigate the early-stage nucleation process of the precipitates. The results reveal that precipitation occurs heterogeneously on plate-like (or disc-like) metastable Cu-enriched GP zones that preferentially inhabit {1 1 0}β planes. Crystallographic orientation analyses suggest that the Ti2Cu phase is related to the matrix via a definite orientation relationship of (01¯3)Ti2Cu∥(011)β and [100]Ti2Cu∥[100]β, while the growth of the α phase is governed by the Potter's OR such that (11¯01)α∥(011)β and [112¯0]α∥[11¯1]β. (01¯3)Ti2Cu and (11¯01)α are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated α and Ti2Cu phases attain a nearly perfect lattice correspondence along certain crystallographic planes, which results in a low interfacial energy configuration and favours the co-development of these phases.

AB - The formation of conjugated precipitates in a ternary Ti-25V-3Cu (wt.%) (Ti-24.4V-2.3Cu (at.%)) alloy subjected to isothermal aging at 500 °C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal α phase and body-centered-tetragonal (bct) Ti2Cu intermetallic compound. These precipitates are composed of two geometrically symmetrical components, which are verified by transmission electron microscopy (TEM) to be twin-related variants of α and Ti2Cu phases. Atomic-level characterizations incorporating high-resolution TEM and atom probe tomography were used to investigate the early-stage nucleation process of the precipitates. The results reveal that precipitation occurs heterogeneously on plate-like (or disc-like) metastable Cu-enriched GP zones that preferentially inhabit {1 1 0}β planes. Crystallographic orientation analyses suggest that the Ti2Cu phase is related to the matrix via a definite orientation relationship of (01¯3)Ti2Cu∥(011)β and [100]Ti2Cu∥[100]β, while the growth of the α phase is governed by the Potter's OR such that (11¯01)α∥(011)β and [112¯0]α∥[11¯1]β. (01¯3)Ti2Cu and (11¯01)α are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated α and Ti2Cu phases attain a nearly perfect lattice correspondence along certain crystallographic planes, which results in a low interfacial energy configuration and favours the co-development of these phases.

KW - Atom probe tomography

KW - Precipitation

KW - TiCu phase

KW - Transmission electron microscopy

KW - β-Titanium alloy

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DO - 10.1016/j.actamat.2014.10.053

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