DIFFUSION OF MN-54 AND FE-59 IN ICOSAHEDRAL AL-PD-MN SINGLE QUASI-CRYSTALS

Self-diffusion of Mn-54 and diffusion of Fe-59 was studied in icosahed ral single quasicrystals of Al70.4Pd21.2Mn8.4 The radiotracer method i n combination with serial sectioning of the diffusion samples was used to determine concentration depth profiles. The temperature dependence s of diffusion are expressed by Arrhenius equations with the following activation enthalpies (Q) and pre-exponential factors (D-0): Mn: Q = 1.99 eV; D-0 = 8.91 x 10(-4) m(2)s(-1), Fe: Q = 2.61 eV; D-0 = 1.63 x 10(-2) m(2)s(-1). The results are compared with the scarce literature data on quasicrystals and with data on diffusion in fee aluminium and in iron aluminide. The quasicrystal data are not significantly differe nt from those in related crystalline materials, for which a vacancy-me diated mechanism is generally accepted for diffusion. Deviation from a n Arrhenius behavior as predicted for phason-assisted diffusion could not be detected.