The migration of Ag in nanocrystalline Cu was measured at 303 to 373K. The specimens were disc-shaped pellets of nanocrystalline material, having an average grain size of 8nm. The Ag was diffused-in from one of the flat surfaces, and the resultant concentration profiles were determined via the electron-beam micro-analysis of taper-sectioned specimens. The results could be described by:

D (cm2/s) = 3.0 x 10-4 exp[-0.63(eV)/kT]

at 353 to 373K, and by:

D (cm2/s) = 1.0 x 10-8 exp[-0.39(eV)/kT]

at 303 to 343K.

S.Schumacher, R.Birringer, R.Strauss, H.Gleiter: Acta Metallurgica, 1989, 37[9], 2485-8