Epitaxial B2-NiAl layers formed by nanosecond laser irradiation of thin Al/Ni bilayers

The results of experiments on the synthesis of epitaxial B2-NiAl layers by means of nanosecond laser irradiation of sequentially deposited thin nickel and aluminum layers (Al/Ni bilayers) on a MgO(001) substrate surface are presented. Features of the phase formation under the laser action and during the combustion wave initiation are considered. The rapid formation of an epitaxial B2-NiAl layer is explained in terms of a martensitic-like mechanism of the transfer of reacting atoms via a layer of reaction products. It is suggested that this mechanism can compete with diffusion via grain boundaries and dislocation, thus explaining the ultrafast transfer of reacting atoms via a layer of reaction products for various methods of initiation of the solid-state synthesis.