[en] The distribution of Ni-63 has been explored over the surface of tungsten polycrystals and monocrystals with the surface orientations in the vicinity of (111) and (305). The character of nickel distribution depends on the surface orientation and temperature. On (111)-vicinals at all the temperatures a usual Brownian migration of adatoms is observed. On the surfaces of a polycrystal or monocrystal with orientation (305) at t (>=) 1050 deg C a distinct boundary of diffusion front is observed which is ''washed away'' at higher temperatures. The distinct boundary appears due to capturing the adatom by traps on the surface. The investigation into the character of the time dependence of the boundary movement has shown that the process of diffusion distribution is controlled not only by the adatoms diffusion velocity, but by the rate of their separation from the source of diffusion