2003 Volume 44 Issue 1 Pages 59-62
Diffusion in FePt has been studied with emphasis on the effect of order-disorder transition by interdiffusion experiments below and above the L10–A1 transition temperature. The chemical diffusion coefficient in the disordered state obeys the Arrhenius law with the effective activation energy of 3.1 eV (1 eV=1.6×10−19 J). Anisotropy of diffusion in the ordered state has been examined using monovariant single-crystals of the tetragonal L10 structure. The coefficient of diffusion in the a-axis direction is slightly lower than the extrapolation of the diffusivity from the disordered state, while that of diffusion in the c-axis direction deviates significantly toward lower values. The apparent activation energy for the diffusion in the two directions is 3.2 and 3.8 eV, respectively.