The effect of heat treatment on microstructural, mechanical and tribological properties of Ti-Ag alloy produced by selective laser melting method

This study systematically investigated the effects of different post-fabrication heat treatments on the microstructural, mechanical, and tribological properties of a novel Ti-Ag alloy produced by selective laser melting (SLM). Unlike conventional powder mixing methods reported in the literature, electroless Ag-coated Ti powders were used as feedstock, enabling controlled Ag distribution in the Ti matrix through post-SLM heat treatments. X-ray diffraction analysis confirmed that the α-Ti-based matrix structure was preserved in all samples, while oxide phases formed after heat treatment. The water-cooled and aged specimen (HT-3) exhibited the highest hardness (508.9 ± 13 HV), corresponding to a 68.8% increase compared to the untreated SLM specimen. This improvement was attributed to Ag-rich precipitate formation and stabilization of rutile/anatase phases. Tensile testing showed that the as-built SLM specimen had the highest tensile strength (639.5 MPa), whereas heat-treated samples showed reduced strength due to oxidation and microstructural changes during cooling. Under 15 N load and 100 m sliding distance, heat-treated specimens demonstrated significantly lower friction coefficients, with HT-3 reaching 0.48 (22.6% reduction). HT-3 also exhibited the lowest volume loss, indicating superior wear resistance and stable friction behavior.