Details

Autor(en) / Beteiligte

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

Titel

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

Ist Teil von

• Acta materialia, 2015-02, Vol.84, p.457-471

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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 degree C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal alpha 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 alpha 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 {110} beta planes. Crystallographic orientation analyses suggest that the Ti2Cu phase is related to the matrix via a definite orientation relationship of and , while the growth of the alpha phase is governed by the Potter's OR such that and . and are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated alpha 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.