Diffusion along the moving reaction front of discontinuous precipitates in Ni-4 at.% Sn alloy

The technique of analytical electron microscopy has been used to determine the solute concentration profiles left behind the moving reaction front of the discontinuous precipitation reaction in a Ni-4 at.% Sn alloy. These profiles have been converted into grain boundary diffusivity values, using Cahn's diffusion equation and the data of the growth rate of the discontinuous precipitates obtained from independent measurements, but relevant for the same individual cell for which the solute distribution had already been obtained. Such a procedure was applied for the first time in the Ni-Sn system ant it provides diffusivity data, which are very similar to the values given in the literature for stationary grain boundaries.