Pulsed plasma nitrided Nb alloyed Mo 3 Si intermetallic alloy

Pulsed nitrided plasma of Mo₃Si intermetallic alloys with different Nb concentrations were treated in a nitrided atmosphere of 50%H₂–50%N₂ at pressure 533 Pa and temperature 950°for 8 h. The pulsed nitrided plasma was studied by optical emission spectroscopy (OES). Strong intensities of N₂, N₂⁺and NH excited states were observed in the OES in the negative glow of H₂–N₂ pulsed plasma. Several alloys with different additions of Nb solid solution were treated. Nitrided specimens were analsed by SEM and X-ray diffraction; microhardness measurements were also evaluated. After the nitrided treatment, the alloy with more than 10 at.-%Nb increased its surface hardness by 16·6%, presumably by the formation of NbN.