The Au diffusion in the Ti3Al compound was investigated at six compositions from 25 to 35at%Al by using the diffusion couples (Ti-Xat%Al/Ti-Xat%Al-2at%Au; X = 25, 27, 29, 31, 32 or 35) at 1273 to 1423K. The diffusion coefficients of Au in Ti3Al, DAuTi3Al, were relatively close to those of Ti. The DAuTi3Al increased slightly with Al concentration within the same order of magnitude. The activation energies of Au diffusion, QAuTi3Al, evaluated from the Arrhenius plots were relatively close to those for Ti diffusion, QTiTi3Al, rather than those of Al diffusion, QAlTi3Al. It was therefore suggested that Au atoms diffuse by the sub-lattice diffusion mechanism in which Au atoms substituted for Ti sites preferentially in Ti3Al and diffuse by vacancy mechanism on Ti sub-lattice. The influence of the D019 ordered structure (hexagonal close-packed base) of Ti3Al on diffusion of Au and other elements was discussed by comparing the diffusivities in Ti3Al and α-Ti.

Diffusion of Au in the Intermetallic Compound Ti3Al. Y.Koizumi, T.Tanaka, Y.Minamino: Metallurgical and Materials Transactions A, 2009, 40[12], 2919-26