Enhanced hardness and wear resistance of powder metallurgy pure titanium via controlled gas nitriding

Powder metallurgy (PM) pure titanium has its wide application limited by its inherent low surface hardness and poor wear resistance despite its near-net shape formability and fine grain size. This study investigates gas nitriding of PM pure titanium, focusing on the effect of processing parameters on the microstructure and surface performance of the nitrided layer. The nitrided layer thickness increases markedly with temperature and time. Thermodynamic and kinetic analyses confirm the nitrided layer evolves sequentially: α-Ti(N), Ti 2 N, and TiN. TEM validates this evolution, revealing a 27.59° misorientation at the TiN/Ti 2 N interface and a coherent Ti 2 N/α-Ti interface, which contribute to strong metallurgical bonding. After nitriding, surface hardness increases three to fourfold, with a 51% reduction in wear volume. The dominant wear mechanism transitions from severe multi-mode wear to mild localized spalling. These findings provide an effective strategy to enhance the surface durability of PM titanium components for wear-resistant engineering applications.