Effects of Mo Introduction Types on the Microstructure and Properties of the Fe–1.1C–15Cu–1.7Ni–7.3Cr–7Co–9Mo Alloys

This study addresses the issue of performance limitations caused by the uneven distribution of high‐melting‐point elements (Mo) in ferrous powder metallurgy materials. It systematically investigates the effects of different types of Mo‐containing powders (pure Mo powder, prealloyed Mo–Fe powder, and mechanically alloyed Mo‐Fe powder) and sintering temperatures (1100, 1150, 1200, and 1250°C) on the microstructure and properties of Fe–1.1C–15Cu–1.7Ni–7.3Cr–7Co–9Mo materials. The research aims to fundamentally improve the uniformity of Mo distribution by preparing Mo–Fe composite powders via a mechanical alloying process. As the sintering temperature increases, the material's properties exhibit a trend of first increasing and then decreasing. Within the temperature range of 1100–1150°C, the rise in temperature promoted atomic diffusion and the formation of liquid Cu, which in turn facilitated particle rearrangement and pore closure, thereby improving the material's densification and mechanical properties. However, beyond 1150°C, oversintering resulted in the accumulation of liquid Cu at grain boundaries and pores, inhibiting effective solid‐state diffusion and densification, which led to a decline in the material's properties. At 1150°C, the sintered samples containing mechanically alloyed Mo–Fe powders showed the highest performance, with a density of 7.50 g cm −3 , Rockwell hardness of 92.36 HRB, and radial crushing strength of 665.72 MPa, which was superior to that of the sintered samples with pure Mo powders and prealloyed Mo–Fe powders. Additionally, the sintered samples with mechanically alloyed Mo–Fe powder demonstrated a more homogeneous microstructure and superior wear resistance, with a coefficient of friction of 0.53, a wear rate of 1.95 × 10 −9 mm 3 N −1 mm −1 , and a wear mass loss of 0.0022 g, representing a 65% reduction in wear mass loss compared to sintered samples containing pure Mo powder.