Wear performance of Nb-alloyed, pulsed plasma nitrided Mo3Si intermetallic

Several alloys produced by arc cast method were obtained, with Nb additions up to 20 at%. The samples were thermo-chemical treated with pulsed plasma nitrided for 24 h. A pin-on-disk system was employed to perform wear experiments under non-lubrication condition. After wear analysis, the treated samples in all range of Nb concentrations have shown less mass losses in comparison with samples without surface modification, until the nitrided zone is removed. Surface oxidation studies leaded to the conclusion that the increased wear resistance is due to the higher surface hardness together with the mixture of different Nb, Si and Mo oxides generated during the wear process identified by SEM and chemical analysis. The friction coefficient is of the order of 10−3. The improved specific wear rate is of the order of 10−6 mm3/N m and shows an increment of 39.9% respect to the samples with 5 at% Nb and 10 at% Nb, this results clearly show that Nb additions is beneficial for the wear resistance of the alloy.