The structure of titanium nickelide surface layers formed by pulsed electron-beam melting

Abstract

X-ray structure analysis technique has been developed for a material heterogeneous over the depth. The structure of the TiNi intermetallide subjected to surface modification by an electron beam has been investigated. The following three layers differentiated in the microcrystalline structure have been singled out: (i) the external sharply textured layer 1–3 μm in thickness with a texture in the [100] B2 direction and a lattice periodicity parameter reduced by 1% in the direction of the normal, (ii) the intermediate gradient-stressed layer 10–15 μm in thickness with the texture of the initial ingot, and (iii) the original material. The crystal lattice of the surface as well as of the intermediate layer is in a state stretched along the surface and compressed along the normal to it. This lattice distortion is maximal in the surface layer and decreases towards the bulk of the material.