The migration of defects and nitrogen atoms in nitrided surface layers of austenitic stainless steel followed by microscopic methods

The X6CrNiTi1810 austenitic stainless steel samples nitrided by plasma immersion ion implantation at 300 °C/3 h are studied by slow positron implantation and conversion electrons Mössbauer spectroscopies completed with X-ray diffraction (XRD) measurements. The surface layers consist of γN-Fe expanded austenite and ε-Fe2N nitride. The changes in hyperfine parameters and relative representation of both phases during the interrupted long-time annealing at 150 °C are discussed from the point of view of nitrogen migration and changes in defect structure.