STRUCTURE OF AUSTENITIC Fe-Ni ALLOYS SURFACE AFTER LASER HEATING. A.V. Nedolya, Faculty of Physics, Zaporizhya State University, 66 Zhukovsky Str., 330600 Zaporizhya, Ukraine

Fe--Ni alloys after laser heating were investigated by X-ray powder diffraction and scanning electron microscopy. As a result it was found that microstructure of alloys was reduced to fragments by laser pulse treatment. Lattice parameter value of solid solution showed abnormally high carbon content at some laser treatment conditions. X-ray investigations of laser heating thin surface layers showed irregular carbon distribution and other alloying elements throughout the treated layer. The research of thin surface layer showed nonmonotonous dependence of austenite lattice parameter deep into treated layer. The carbon concentration in austenite of these laser-heated zones was more than its concentration after hardening in water and as a result, the lattice parameter of austenite increased.