High pressure nitrogen gas alloying of Fe-Cr-Ni alloys

The concentration of nitrogen in molten Fe-Cr-Ni alloys has been substantially increased by melting under nitrogen overpressures. Total nitrogen concentrations exceeding 26 at % were obtained when melted under 200 MPa. Nitrogen is present in solidified alloys as interstitial nitrogen and as metal nitrides. The nitrogen concentration depends upon the alloy composition; nickel decreases the nitrogen concentration, whereas chromium increases the concentration. When iron and Fe-Ni alloys were melted under high nitrogen pressures they produced iron nitrides and when Fe-Cr-Ni alloys were melted they produced ON dendrites and precipitates.