Optimizing the Microstructure and Properties of Fe–Ni–Cu–Mo–C Sintered Steel by TiB₂

The Fe–Ni–Cu–Mo–C powder metallurgy sintered steels with TiB 2 reinforced were prepared by the conventional powder metallurgy techniques. This study explored the influence of incremental TiB 2 additions, ranging from 0.1 to 0.6 wt.%, on the microstructure and properties of these steels. The results reveal that the microstructures primarily consist of martensite, Ni-rich austenite, Cu-rich pearlite, TiB 2 , and Ti–O rich nanoparticles. The latter form via a reaction between TiB 2 and free oxygen. Notably, both the density and impact strength of the steels showed enhancement with increasing TiB 2 content. The optimal values, 7.25 g/cm 3 for density and 17.23 J/cm 2 for impact strength, were observed at a TiB 2 concentration of 0.5%. The hardness and ultimate tensile strength also increased steadily, reaching maxima of 38.7 and 1083.7 MPa at 0.6% TiB 2 , respectively. However, excessive TiB 2 led to the formation of a net-like B-containing eutectic network, adversely affecting the steel properties. Steels with 0.5% TiB 2 exhibited excellent wear resistance. At 200 rpm, the dominant failure mode was abrasive wear, which shifted to adhesive wear with oxidation at 400 rpm, followed by abrasive wear.