Effect of interstitial impurities on liquidus temperatures in Ti–Al alloys

Development of intermetallics in Ti–Al alloys for high-temperature structural applications has long been impeded by embrittlement, partly because there has been a complete understanding at an electronic level on the Ti–Al phase transformation behavior. In this study, based on the Empirical Electron Theory of Solids and Molecules (EET), effects of interstitial impurities on valence electron structures and liquidus temperatures in Ti–Al phase diagram are analyzed. Based on the theoretical analysis, some unclear experimental results in Ti–Al phase diagram are further discussed. It is demonstrated that because of the effects of interstitial impurities, the valence electron structures become seriously anisotropic, leading to the lowest liquidus temperatures in Ti–Al phase diagram.