Microstructure and properties of alumina ceramic particle reinforced Fe–Ni–Mo–C–Cu composites prepared by powder forging

The Fe–Ni–Mo–C–Cu (Q61) composites reinforced by Al₂O₃ particles with different contents were prepared by powder forging. The microstructure and properties of the tempered and quenched Q61 composites were studied. The results show that, when the mass fraction of Al₂O₃ is 0.15%, the Al₂O₃ particles are distributed homogeneously in the matrix. Compared with the single Q61 without reinforced particles under the same state, the hardness and yield strength of the tempered composites are increased from HRC 38 and 1106 MPa to HRC 39.8 and 1121 MPa, respectively, while the elongation is decreased from 12% to 6.5%; the hardness of the quenched Q61 composites is enhanced from HRC 61.5 to HRC 63.2, and the wear rate is reduced from 5.27×10⁻⁶ mm³·m⁻¹·N⁻¹ to 3.08×10⁻⁶ mm³·m⁻¹·N⁻¹, lower than that of the typical 40Cr gear materials (3.34×10⁻⁶ mm³·m⁻¹·N⁻¹). However, the Al₂O₃ particles are aggregated gradually when the Al₂O₃ addition content is more than 0.15%. Though the yield strength is still improved, the plasticity is reduced significantly for the tempered composites, and the wear rate is greatly increased for the quenched composites, showing the degraded wear resistance. In summary, the Q61 composites with 0.15% Al₂O₃ particles show the higher comprehensive mechanical properties in the tempered state and the good wear resistance in the quenched states, respectively.