Ti-45at%Al MA粉末の焼結にともなう組織変化 (メカニカルアロイング<特集>)

概要

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The structure of a mechanically alloyed Ti-45at%Al powder and its decomposition behavior during sintering have been investigated by X-ray diffraction (XRD) and analytical transmission electron microscopy (TEM). By the XRD experiments, the powder after 200 hr mechanical alloying is shown to be consisted of two phases, Ti3A1 and TiAI. The volume fraction of Ti3Al is estimated to be larger than that of TiAI, while for the sintered compact of the powder this tendency was reversed. The mechanically alloyed powder is composed of strain free fine grains (grain size ranging from 10 to 20 nm in diameter). The average composition of the grains are approximately Ti-45at%Al. Therefore, the powder may be assumed to be composed mainly of Al supersaturated Ti3Al. The results of XRD and analytical TEM experiments suggest that the decomposition of the supersaturated Ti3AI to equilibrium Ti3Al and TiAI took place during sintering.