The magnetic properties and microstructure of sintered iron-phosphorus and iron-silicon-phosphorus compacts have been investigated. Measurements of maximum permeability (μmax) and coercive force ($H_c$) were performed with hysteresis graph tracer.
The densification rate of iron powder with phosphorus was greater than that of pure iron powder. At the same sintering temperature, the increased phosphorus content in iron caused $B_{10},B_r$, μmax to increase and $H_c$ to decrease. For the same composition, the higher sintering temperature the higher μmax and the lower $H_c$. These phenomena were discussed on the basis of enhanced sinterability and pore distribution due to the presence of phosphorus. It was found that $H_c$ decreased as grain size increased and that increasing numbers of fine pores in the grain caused μmax to decrease and $H_c$ to increase.
In Fe-3wt.%Si-P system, phosphorus addition (0.8 wt.%) enhanced sinterability but decreased μmax and increased $H_c$. These phenomena were discussed in terms of pore distribution and the formation of secondary phases in the grain and the formation of amorphous phase in the grain boundary.
The resistivities of sintered compacts (Fe-P and Fe-3wt.%Si-P system) were increased with increasing phosphorus addition.
