Stoichiometry dependent inter diffusion and structural evolution in Al-Ni multilayer

Ni-aluminides are an important class of intermetallics from research and technological point of view. Ultrathin multilayers of Ni and Al with overall stoichiometric ratio as 3:1 (Ni rich) and 1:3 (Al rich), respectively, were characterized by X-ray diffraction, X-ray reflectivity and polarized neutron reflectivity after sequential annealing at 150 °C, 200 °C and 300 °C to track the structural changes at mesoscopic and microscopic length scales. Morphology of the as deposited and annealed states were examined by atomic force microscopy. The impact of stoichiometric difference on the diffusion mechanism and its influence on structural parameters like alloy layer thickness, magnetic moment and crystallite size was studied in detail for these systems. Activation energies for these systems were also obtained through Arrhenius plots extracted from reflectometry data.