Secondary-ion mass spectrometry was used to measure bulk gold diffusion coefficients at 1300 to 2000K in monocrystalline iridium, annealed under ultra-high vacuum. The results could be described by:

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

It was shown, using the linear dependence of the enthalpy of activation of self-diffusion, QSD, of d transition metals on the universal homologous temperature,

V = 0.3Tm + 0.7θ

that the available parameters for the bulk self-diffusion of iridium agreed with the linear dependence QSD(V) for the d transition metals, and that the corrected value was (QSD)Ir = 449kJ/mol. The difference in the enthalpies of activation of the bulk diffusion of gold and of self-diffusion in iridium agreed qualitatively with the available charge dependences of such differences for the bulk diffusion of isocoric impurities in single crystals of tungsten and gold.

Bulk Diffusion of Gold in Single-Crystal Iridium. A.V.Ermakov, S.M.Klotsman,  S.A.Matveev, G.N.Tatarinova, A.N.Timofeev, V.K.Rudenko, N.I.Timofeev: Fizika Metallov i Metallovedenie, 2001, 92[2], 87-94