In this study, different alloys with the composition Fe-Co-Mo-V were analysed. These alloys often form precipitations of the intermetallic (Fe, Co)7Mo6 µ-phase. The aim of this work was to form micrometer-sized vanadium nitrides in the surface layer using different nitriding techniques. Therefore, different amounts of V were added to the alloy and nitriding treatments were performed. The influence on phase stability, dissolution of primary µ-phase and surface hardness was investigated. The methods used included thermodynamic calculations applying MatCalc and Thermo-Calc, dilatometer heat treatments, glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD) as well as electron backscatter diffraction (EBSD).