Fachbereich 11 - Physik
Institut für Materialphysik
Diffusion in Metals, Intermetallics, Silicides, Quasicrystals and Metallic Glasses

Diffusion quasicrystalline alloys

Quasicrystalline alloys are no longer laboratory curiosities. Nowadays some applications are already close to the market. Diffusion is an important topics in the materials science of quasicrystals. In a cooperation within a DFG Schwerpunktprogramm of our group and a group at the Max-Planck-Institut für Metallforschung at Stuttgart we summarised common efforts in the area of diffusion in quasicrystals. The investigations comprise studies of solute and self-diffusion in icosahedral Al-Pd-Mn and Zn-Mg-RE (RE = Ho, Y) as well as decagonal Al-Ni-Co quasicrystals, which were performed mostly by radiotracer techniques. In addition to measurements of the temperature dependence, in Al-Pd-Mn the dependencies of the diffusivities of Zn and Mn on hydrostatic pressure and the influence of particle irradiation on the diffusion of Pd and Au were studied, whereas for in Al-Ni-Co emphasis was laid on the determination of the diffusion anisotropy. It was found, that in all quasicrystals investigated diffusion is mediated by thermal vacancies. An exception is the diffusion Au and Pd in the low-diffusivity regime. This was proposed to occur via a direct diffusion mechanism that is assisted by collective phason flips.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft (Schwerpunktprogramm: 'Quasikristalle - Struktur und physikalische Eigenschaften')

Beteiligte Wissenschaftler:

Prof. W. Assmus (Universität Frankfurt), Dr. Renate Blüher (MPI für Metallforschung, Stuttgart), Dipl.-Phys. R. Galler, Prof. Dr. W. Frank (MPI für Metallforschung, Stuttgart), Dipl.-Phys. Chr. Khoukaz (bis April 2000), Prof. Dr. H. Mehrer (Universität Münster, Leiter), Dr. R. Sterzel (Universität Frankfurt), Dr. A. Strom (MPI für Metallforschung, Stuttgart)

Veröffentlichungen:

Khoukaz, Chr.; R. Galler, M. Feuerbacher, H. Mehrer:Self-diffusion of Co and Ni in decagonal Al-Ni-Co quasicrystals, Defect and Diffusion Forum 194 - 199, 873 - 882 (2001)

Galler, R., R. Sterzel, W. Assmus, H. Mehrer: Diffusion in icosahedral Zn-Mg-RE and Al-Pd-Mn quasicrystals, Defect and Diffusion Forum 194 - 199, 867 - 872 (2001)

Mehrer, H., R. Galler: Vacancy-mediated diffusion in quasicrystalline Alloys, J. of Alloys and Compounds 342, 296 - 301 (2002)

Mehrer, H., R. Galler, W. Frank, R. Blüher, A.Strohm: Diffusion in quasicrystals; Chapter in: Quasicrystals:Structure and Physical Properties, edited by H.-R. Trebin, J.Wiley-VCH, pp. 321 - 337, 2003.