Observation of a new B2 structured phase in Ti-15Mo (wt%)

Journal Article · Wed Aug 15 00:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.06.017· OSTI ID:22805107

Bennett, J. M. ^[1]; Pickering, E. J. ^[1]; Barnard, J. S. ^[1]; Rugg, D. ^[2]; Stone, H. J.

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1. Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)
2. Rolls-Royce plc, PO Box 31, Derby DE24 8BJ (United Kingdom)

Highlights: • Ti-15Mo (wt%) studied in TEM during in situ heat treatment at 300 °C. • Initial microstructure (beta and athermal omega) evolved during exposure. • New B2 phase observed during heat treatment of electron transparent material. • B2 phase formed in regular arrays of square cross-section particles. • B2 phase lattice parameter smaller than beta phase resulting in misfit strain - Abstract: The formation of non-equilibrium and transient phases in metastable beta titanium alloys during low temperature thermal treatments is currently of great interest, as they provide a potential method of controlling the size and distribution of the equilibrium alpha phase and, hence, the resulting mechanical properties. Here, for the first time, we report on the formation of a new, B2 structured phase in the Ti-Mo system. The phase was observed in electron transparent material during in situ, and following ex situ, heat treatment at 300 °C. The B2 phase was enriched in Mo compared to the surrounding matrix material and formed in regular arrays of approximately square cross-section particles interspersed by thin beta channels. Electron diffraction indicated that the lattice parameter of this new phase was smaller than that of the parent phase, leading to significant strain in the beta channels. Critically, the B2 phase was only observed in material that had been electro-polished prior to heat treatment, and, therefore, it is hypothesised that this phase forms as a result of the preparation method and thin foil effects.

• OSTI ID: 22805107
• Journal Information: Materials Characterization, Vol. 142; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINARY ALLOY SYSTEMS
COMPARATIVE EVALUATIONS
DISTRIBUTION
ELECTRON DIFFRACTION
FOILS
HEAT TREATMENTS
LATTICE PARAMETERS
MATRIX MATERIALS
MICROSTRUCTURE
MOLYBDENUM COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
TITANIUM COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY