The grain-boundary diffusion of Cr in Nb bi-crystals with 8° [¯110]/[112] symmetrical tilt boundaries was measured at temperatures ranging from 947 to 1150C by using electron probe microanalysis methods. The dependence of the grain-boundary diffusion coefficient upon temperature was described by:

D (cm2/s) = 0.0116 exp[-42.961(kcal/mol)/RT]

X.M.Li, Y.T.Chou: Philosophical Magazine Letters, 1992, 66[6], 281-5