Interdiffusion coefficients in the B2-type phase were determined by using single-phase diffusion couples at 1073 to 1773K. The value of the interdiffusion coefficient exhibited a minimum at about 47at%Al; deviating slightly from the stoichiometric composition. The value of the activation energy for interdiffusion exhibited a maximum at about 47at%Al. The magnitude of the activation energy for diffusion in CoAl was suggested to be related to the lattice constant of the compound.

Single-Phase Interdiffusion in the B2-Type Intermetallic Compounds NiAl, CoAl and FeAl. R.Nakamura, K.Takasawa, Y.Yamazaki, Y.Iijima: Intermetallics, 2002, 10[2], 195-204