The self-diffusion of 57Co in decagonal single quasicrystals was studied, for both principal directions, by using radiotracer methods and serial sectioning. The diffusivities were measured at 732 to 1273K. The diffusion, below about 1120K, could be described by an Arrhenius relationship for both the periodic and the quasi-periodic directions. The magnitudes of the activation enthalpies and pre-exponential factors indicated a vacancy-type diffusion mechanism. A small diffusion anisotropy was detected which was temperature-dependent but which never exceeded 30%. A kink in the Arrhenius plot was observed above 1120K. This behaviour was attributed to a phase transition from the decagonal Co-rich phase to an ordered form.

Diffusion of 57Co in Decagonal Al-Ni-Co Quasicrystals. C.Khoukaz, R.Galler, H.Mehrer, P.C.Canfield, I.R.Fisher, M.Feuerbacher: Materials Science and Engineering A, 2001, 294-296, 697-701