Diffusion couples, which were in the form of a small flake of Nd that was compacted into Fe powder, were held at temperatures of 953, 993, 1053 or 1253K for up to 25h. The composition profiles were obtained by means of the scanning electron microscopic energy-dispersive X-ray analysis of sections that had been cut from the couples. The presence of specific reaction products was confirmed by X-ray diffraction. At temperatures of 993K and above, the Nd flake rapidly became a liquid as the in-diffusion and dissolution of Fe depressed the melting point. At higher temperatures, a single reaction product (Fe17Nd2) was found. At 953K, 2 reaction products (Fe17Nd2, Fel7Nd5) formed. The diffusion reactions were quasi steady-state, and the growth of the reaction products obeyed a parabolic law. Wagner’s theory was used to calculate the interdiffusion coefficients for the products. Data for the reaction product, Fe17Nd2, obeyed an equation of the form,

D (m2/s) = 8 x 10-7exp[-127(kJ/mol)/RT]

D.Zhang, I.R.McColl, J.V.Wood: Philosophical Magazine A, 1997, 75[4], 959-74