INTERDIFFUSION IN THE TI-RICH PHASES OF THE TI-AL SYSTEM

The interdiffusion coefficient ((D) over tilde) has been measured in t he temperature range from 1442 to 1639 K as a function of the composit ion in the alpha (hexagonal close-packed, A3), alpha(2) (ordered hexag onal, D0(19)), beta (body-centred cubic, A2) and gamma (ordered face-c entred cubic, L1(0)) phases of the Ti-Al system. The concentration pro files were obtained by electron probe microanalysis, and the chemical diffusivity was extracted from the concentration profiles by the Boltz mann-Matano procedure. In all the phases the interdiffusion coefficien ts increase with increasing Al contents. This increase is large in the disordered phase alpha, but much smaller in the ordered phases alpha( 2) and gamma.