Effect of Cu-15Sn on the microstructure and mechanical properties of pressureless sintered Fe-Co-Cu alloy.

Fe-Co-Cu alloys were prepared by pressureless sintering at 875 °C. The effects of pre-alloyed Cu-15Sn sintering aids on the microstructure and mechanical properties of Fe-Co-Cu alloys were investigated. The results show that the Cu-15Sn aids makes the sintering densification process of Fe-Co-Cu alloy changes from solid phase sintering to instantaneous liquid phase sintering, which improves atomic diffusion rate and relative density of alloys, and also makes the matrix grains grow up. The relative density, hardness and bending strength of Fe-10 wt% Co-15 wt% Cu alloy can be significantly improved by adding 7 wt% Cu-15Sn, which can reach 96.34 %, 85 HRB, and 1857 MPa, respectively. The volume fraction of Cu-rich phase, the relative density of the alloy and the grain size have great influence on the hardness and bending strength of the alloy. When there are too many liquid phases, the relative density of the alloy decreases, making it difficult to continue to improve the strength of the alloy. Intergranular brittle fracture occurs mainly in α-Fe phase grains, but dislocation slip deformation occurs in Cu-rich phase grains. With the increase of volume fraction of Cu-rich phase and relative density, the alloy gradually exhibits macroscopic plasticity. • Cu-15Sn aids improves relative density, hardness and bending strength. • Intergranular brittle fracture change to macroscopic plasticity. • Solid phase sintering changes to liquid phase sintering. [ABSTRACT FROM AUTHOR]