The diffusion of Cr was studied by using the 51Cr radioactive tracer, and serial sectioning methods, at temperatures ranging from 1060 to 1510K (lattice diffusion) or from 775 to 1170K (grain boundary diffusion). It was found that the lattice diffusivity could be described by:

D(m2/s) = 3.24 x 10-4exp[-287.4(kJ/mol)/RT]

The grain boundary diffusivities were usually deduced by using the Whipple method, although the Suzuoka method was sometimes used. The 2 methods yielded grain boundary diffusion coefficients which were in good agreement with each other. The grain boundary diffusivity could be described by:

D(m2/s) = 5.80 x 10-5exp[-184.2(kJ/mol)/RT]

Mass transport along the grain boundaries was also extensively studied by using an autoradiographic technique. It was observed that, in small-grained specimens at temperatures of less than 980K, long-range transport of tracer atoms occurred mainly via the grain boundaries.

A.R.Paul, K.N.G.Kaimal, M.C.Naik, S.R.Dharwadkar: Journal of Nuclear Materials, 1994, 217[1-2], 75-81