Mechanism of formation of nanocrystalline particles with core-shell structure based on titanium oxynitrides with nickel in the process of plasma-chemical synthesis of TiNi in a low-temperature nitrogen plasma

This paper presents the results of experiments, structural and morphological certification and modeling of ultrafine and nanocrystalline TiN-Ni "core-shell" structures obtained during plasma-chemical synthesis of industrially manufactured microcrystalline TiNi. Experiments on plasma-chemical synthesis were carried out by recondensation of ultrafine and nanocrystalline powders in a rotating cylinder of gaseous nitrogen. X- ray phase analysis and high-resolution transmission electron microscopy (HR TEM) showed the presence of refractory titanium compounds with nitrogen and metallic nickel, which are part of the core-shell structures, including the metastable, highly deformed complex nitride Ti$_{0.7}$Ni$_{0.3}$N of hexagonal modification. HR TEM studies showed the localization of phases determined by X-ray diffraction and confirmed the “core-shell” structure on the example of nanocrystalline TiN-Ni fraction. Based on the experimental results, we have developed a model of crystallization of TiN-Ni "core-shell" structures under the conditions of a rotating cylinder of gaseous nitrogen, where the crystallization rate is 10$^5$ $^\circ$C/s.