HIP-driven microstructural evolution in TiN/Ti cermet-modified layers enhances wide temperature range wear resistance

This study investigates the optimization of cermet-modified layers (CML) on Ti6Al4V titanium alloy surfaces, prepared via laser sintering-assisted nitrogen reaction followed by hot isostatic pressing (HIP) post-treatment. The laser-sintered CML exhibited high residual tensile stresses (~800 MPa), metastable α'-Ti phases, and dislocation cells, leading to high hardness but low ductility and crack susceptibility. HIP treatment at 900 ℃ and 150 MPa induced phase transformation from needle-like α'-Ti to homogenized α/β-Ti phases and promoted TiN (tetragonal) precipitation, reducing residual stresses by ~8-fold and enhancing both plasticity and hardness (from 848 to 908 HV). The TiN/Ti interface evolved from a stacked-fault structure to a coherent boundary with a ~1 nm amorphous transition layer, strengthening interfacial bonding and suppressing crack propagation. These microstructural changes resulted in a strength-toughness synergy, improving wear resistance by ~25% at 25 ℃ and ~3.6 times at 500 ℃, attributed to enhanced TiN particle retention and a robust friction glaze layer. The findings provide insights into tailoring cermet-modified titanium alloys for superior tribological performance across a broad temperature range.