Investigation of Microstructure and Wear Properties of Plasma Nitrided Astaloy Mo

In this research, plasma nitridation is carried out on the as-sintered and hardened Astaloy Mo in order to improve the wear behavior of PM parts. The starting materials including pre-alloyed powders with 0.8% graphite were pressed at different pressures. Next, the specimens were sintered at 1120 °C for 30 min, in the N₂/H₂ atmosphere. The effects of density and cooling rate were studied on the microhardness, microstructure, and wear performance of as-sintered and hardened specimens. X-ray technique, scanning electron microscopy, and energy dispersive spectroscopy were used for phase transformation, morphology characterization, and elemental analysis, respectively. The results showed that plasma nitridation and an increase in cooling rate and density up to 6.8 g/cm³ resulted in a change in wear resistance. Moreover, the wear performance of dense samples was decreased due to the enhanced three-body abrasive mechanism.