Secondary-ion mass spectrometry was used to measure the coefficients of bulk diffusion of Au at 1300 to 2000K in monocrystalline Ir which had been annealed in an ultra-high vacuum. The Arrhenius plots of the diffusion data could be described by:

D (m2/s) = 4.92 x 10-5exp[-423.2(kJ/mol)/RT]

It was shown, by using the linear dependence upon the homologous temperature (V = 0.3Tm + 0.7θ), of the activation enthalpy for self-diffusion of d transition metals, that the available parameters for bulk self-diffusion in Ir agreed completely with the linear dependence for d transition metals and that the corrected activation enthalpy was equal to 449kJ/mol. The difference in the activation enthalpies for Au bulk diffusion, and self-diffusion, in Ir agreed qualitatively with the available charge dependences of such differences for the bulk diffusion of isochoric impurities in single crystals of W and Au.

A.V.Ermakov, S.M.Klotsman, S.A.Matveev, G.N.Tatarinova, A.N.Timofeev, V.K.Rudenko, N.I.Timofeev: Physics of Metals and Metallography, 2001, 92[2], 185-92