Research on Microstructure and Properties of Laser‐Deposited TC4/Stellite 6 Functionally Graded Materials

Functionally graded materials (FGMs) of Stellite 6/TC4, crack‐free, were successfully fabricated on TC4 titanium alloy using laser metal deposition (LMD), with gradient compositions of 25%, 30%, and 35% Stellite 6. The study shows that as the Stellite 6 content increases, CrTi solid solution, TiCo intermetallic compounds, and TiC hard phases precipitate sequentially. The gradient design effectively mitigates thermal stress and prevents cracking typically associated with direct cladding of high Stellite 6 content (35%). In terms of performance, the surface layer achieves a microhardness of 690 HV, a friction coefficient of approximately 0.4 at 600°C, and a significantly reduced volumetric wear rate of only 0.195 × 10–3 ± 0.017 mm ³ /(N·m), representing a 72% improvement over the TC4 substrate. Corrosion resistance exhibits nonmonotonic behavior: the 25% Stellite 6 layer performs best due to the formation of a dense passivation film, with a corrosion current density as low as 1.41 ± 0.11 μA/cm ² , while the 30% and 35% layers show reduced resistance due to microgalvanic corrosion.