Nanoprecipitation in a beta-titanium alloy

Coakley, James and Vorontsov, Vassili A. and Littrell, Kenneth C. and Heenan, Richard K. and Ohnuma, Masato and Jones, Nicholas G. and Dye, David (2015) Nanoprecipitation in a beta-titanium alloy. Journal of Alloys and Compounds, 623. pp. 146-156. ISSN 0925-8388 (https://doi.org/10.1016/j.jallcom.2014.10.038)

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Abstract

This paper represents the first application of small angle neutron scattering (SANS) to the study of precipitate nucleation and growth in β-Ti alloys in an attempt to observe both the precipitation process in-situ and to quantify the evolving microstructure that affects mechanical behaviour. TEM suggests that athermal ω can be induced by cold-rolling Gum metal, a β-Ti alloy. During thermal exposure at 400°C, isothermal ω particles precipitate at a greater rate in cold-rolled material than in the recovered, hot deformed state. SANS modelling is consistent with disc shaped nanoparticles, with length and radius under 6nm after thermal exposures up to 16h. Modelling suggests that the nanoprecipitate volume fraction and extent of Nb partitioning to the β matrix is greater in the cold-rolled material than the extruded. The results show that nucleation and growth of the nanoprecipitates impart strengthening to the alloy.