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

Abstract

The Fe–Ni–Cu–Mo–C powder metallurgy sintered steels with TiB2 reinforced were prepared by the conventional powder metallurgy techniques. This study explored the influence of incremental TiB2 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, TiB2, and Ti–O rich nanoparticles. The latter form via a reaction between TiB2 and free oxygen. Notably, both the density and impact strength of the steels showed enhancement with increasing TiB2 content. The optimal values, 7.25 g/cm3 for density and 17.23 J/cm2 for impact strength, were observed at a TiB2 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% TiB2, respectively. However, excessive TiB2 led to the formation of a net-like B-containing eutectic network, adversely affecting the steel properties. Steels with 0.5% TiB2 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.