Investigation of Microstructure Formation in the near-Surface Layers of the Nickel Titanium ALLOY After Silicon ION-Plasma Impact

In the present paper the authors describe the use of electron backscattering diffraction (EBSD) mapping and transmission electron microscopy (TEM) to study of the gradient structures in layered composite materials of the Nickel Titanium alloy and Silicon. With the use of the high-dose ion implantation or magnetron deposition technique was produced a layerwise composite material on the Nickel Titanium based alloys. It was found that the gradient changes of structure is formed under the ion modified surface or under the Silicon coatings on the TiNi surface. For example, the layer by thickness 5-10 microns made of a mix of the grains which are in deformed, fragmented and recrystallized conditions is observed under ion modified surface. A sizes of such grains are significant smaller then a sizes of the initial grains of the parent B2 phase. It was found that studied surface treatments influence on the sequence and temperatures of the martensite transformations in the TiNi alloy.