Electronic structures and transformations of intermediate phases and intermetallic compounds of binary Ti-Al alloys

Effects of interstitial impurities on valence electron structures and phase transformation of Ti-Al alloys are analyzed using the average lattice and atom models of the empirical electron theory of solids and molecules (EET). The descendant degree of bond energy, melting point, and liquidus temperatures affected by interstitial impurities are calculated based on the bond energy formula of the EET. It is demonstrated that because of the effects of interstitial impurities, the atom states of the intermediate phases increase, and bond structures of intermetallic compounds become seriously anisotropic, which results in very complex phase transformations in intermediate Al content. It is also shown that the melting point and liquidus temperatures decrease due to interstitial impurities, and the average decreased degree can be estimated very well using the EET.