Analysis of Interface Reactions of TiAl/Al₂O₃ and TiAl/TiO₂ by the Use of Chemical Potential Diagram

Abstract

Interface reactions for TiAl/Al₂O₃ and TiAl/TiO₂ have been investigated by the present study and the reaction for Ti/Al₂O₃ and the oxidation reaction of TiAl obtained from the literatures have been analyzed by the use of chemical potential diagram of Ti-Al-O system, The layer sequences for these interface reactions are summarized as follows.
(1) TiAl/Al₂O₃ at 1273K: No essential reaction occurred.
(2) TiAl/Al₂O₃ at 1373K; TiAl(O)/Ti₃Al(O)/Al₂O₃
(3) Ti/Al₂O₃ at 1373K for a thick sample by Choi et al.: Ti/Ti₃Al(O)/TiAl(O)/Al₂O₃
(4) Ti/Al₂O₃ at 1373K for a thin sample by Choi et al.: Ti₂O/Ti₃Al(O)/Al₂O₃
(5) Ti/Al₂O₃ at 1273K by Hatakeyama et al.: Ti/Ti₃Al(O)/TiAl(O)/Al₂O₃
(6) Oxidation of Ti-42at% Al at 1273K by Hatakeyama et al.: TiAl/Al₂O₃/Al₂O₃+TiO₂/TiO₂
(7) Oxidation of Ti-36.3at% Al at 1173K by Shida and Anada: TiAl/Ti₃Al(O)/Al₂O₃+TiO₂/Al₂O₃/TiO₂
These reaction paths have been reasonably elucidated by the use of chemical potential diagram of Ti-Al-O system, which was constructed using the data of Gibbs energy of formation of the compounds composed of Ti, Al and O.