Diffusion in decagonal Al-Ni-Co quasicrystals

Single-quasicrystals of decagonal Al_72.6Ni_10.5Co_16.9 (D-AlNiCo) were produced by the flux-growth technique. Diffusion of ⁵⁷Co and ⁶³Ni was studied by the radiotracer method in both principal directions of the degaconal quasicrystals. In addition ⁶³Ni diffusion was studied in coarse-grained polycrystals of D-Al_70.2Ni_15.1Co_14.7 grown by the Bridgman technique. Close similarities between the diffusion behaviour in pure Co, Ni and in D-AlNiCo, and in particular the small diffusion anisotropy suggest a vacancy-mediated diffusion mechanism for D-AlNiCo. Similar magnitudes of the Ni diffusivities in D-Al_72.6Ni_10.5Co_16.9 and in D-Al_70.2Ni_15.1Co_14.7 show that the composition dependence of diffusion within the phase field of the decagonal quasicrystalline phase is weak.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft (Schwerpunktprogramm "Quasikristalle")

Beteiligte Wissenschaftler:

Dr. P.C. Cranfield (Iowa State University, USA), Dr. M. Feuerbacher (Forschungszentrum Jülich), Dr. I.R. Fisher (Iowa State University, USA), Dipl.-Phys. R. Galler, Dipl.-Phys. Chr. Khoukaz (bis Mai 2000), Prof. Dr. H. Mehrer (Leiter)

Veröffentlichungen:

Khoukaz, Chr., R. Galler, H. Mehrer, P. C. Cranfield, I. R. Fisher, M. Feuerbacher: Diffusion of ⁵⁷Co in decagonal Al-Ni-Co quasicrystals, Mat. Sci. Eng. 294 - 296, 697 - 701 (2000)

Khoukaz, Chr., R. Galler, M. Feuerbacher, H. Mehrer: Self-diffusion of Co and Ni in decagonal Al-Ni-Co quasicrystals, Mat. Sci. Forum, in print