Keywords: بازتابنده قطبی نوترون; X-ray reflectivity; Polarized neutron reflectivity; Interdiffusion; Self-diffusion; Intermetallic alloy phases; Annealing; Diffusion length; Solid state reaction; Activation energy for diffusion; Ni/Al, Ni/Ti and Ni/Ge multilayers; XRD; X-ray diffraction;