Sulfurizing treatments on the surface of iron powder for preparing high density Fe-Cu-C alloys

Breaking through the conventional P/M processing, a new process for preparing high density Fe-Cu-C alloys was designed. Through sulfuring treatments on the surface of iron powder, Fe reacts with moderate S to generate FeS, which is uniformly coated on the surface of iron powder particles and formed a thin-layered FeS lubrication film. The FeS lubrication film is useful for reducing the friction of compaction. The phase, element distribution and microstructure were characterized by X-ray diffraction, scanning electron microscopy and field emission scanning electron microscopy. The results show that the FeS lubrication film coating on the surface of iron powder is significant to improve the green density and activate sintering. After sulfuring treatments, Fe-2Cu-0.8C alloys with 0.5% S exhibit higher mechanical properties:the green density reaches 7.31 g·cm^-3, the hardness 78.6 HRB, and the tensile strength 485 MPa. When the mass fraction of S is 0.8%, redundant FeS accounts for pressing volume fraction, resulting in the decreasing of green density and mechanical properties.