Effect of ball milling on the rheology and particle characteristics of Fe–50%Ni powder injection molding feedstock

•Ball milling resulted in a 10% improvement of powder loading.•The rheological properties of feedstock was improvement.•High-performance Fe–50%Ni alloy was produced by powder injection molding. Fe–50%Ni soft magnetic alloys were produced by powder injection molding (PIM) using carbonyl iron and carbonyl nickel as raw materials. The effect of mixing technique of metal powders on the characteristics of mixed powders and PIM process was studied. It was found that the branched chain of carbonyl nickel was broken and the mixture was homogeneous with a good dispersion by ball milling. Due to the improvement of the powder characteristics, the tap density increased from 3.21g/cm3 for mixed powders without ball milling to 4.86g/cm3 for ball mixed powders. Additionally, the critical powder loading of the feedstock was raised from 52% for the mixed powders without ball mixing to 62% for the ball milled powders, which benefited dimension precision. As the degreased specimen sintered at 1360°C in a flowing hydrogen gas, the high magnetic property Fe–50%Ni alloy with maximum permeability of 43541, saturation induction of 1.48T, coercive force of 6.8A/m and relative density of 97% was obtained.