日本金属学会誌

J. Japan Inst. Metals, Vol. 67, No. 11 (2003),
pp. 635-642

Study on Initial Stages of Formation and Growth of Aged ω-Phase Crystals in a Ti-15 mass%Mo Alloy using an Analytical Electron Microscope

Hajime Matsumoto, Eiichi Sukedai and Hatsujiro Hashimoto

Department of Mechanical Systems Engineering, Faculty of Engineering, Okayama University of Science, Okayama 700-0005

Abstract:

Clarification of onset time of formation and formation behaviour of aged ω-phase crystals from as-quenched ω-phase crystals is essential to understand β-ω phase transformation in β-Ti and Zr alloys. The onset time and the formation behaviour in a Ti-15 mass%Mo alloy due to aging at 323 K has been investigated using in-situ observation of morphology change of ω-phase crystals, and EDS analysis of Mo contents in ω-phase crystals and their surrounding matrices. It is found that the difference of Mo contents between as-quenched ω-phase crystals and their surrounding matrices is hardly detected. The onset time determined by the Mo contents analysis is 25.2 ks, which is shorter than that determined by the morphology change observations. Aged ω-phase crystals grow at as-quenched ω-phase crystals. Due to aging at 373 K for 54 ks and at 423 K for 21.6 ks, the growth of aged ω-phase crystals was observed, and these results suggest that aged ω-phase crystals grow due to Ostwalt ripening mechanism.


(Received July 28, 2003)

Keywords:

aged ω-phase crystals, as-quenched ω-phase crystals, Ti-15 mass%Mo, electron microscope, in-situ observation, initial stage, growth mechanism, morphology change, energy dispersive spectroscopy (EDS) analysis, Ostwalt ripening mechanism


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