Effect of particle size distribution on the density and shrinkage of gas-atomized ferrous alloy powder compacts were investigated by controlling particle size distribution of the two bimodal ferrous alloy powders (-25 μm/125-150 μm, 25-46 μm/125-150 μm). These powders were sintered at 1473 K in vacuum after compacted at the pressure of 490 MPa. As a result, the sintered compact of -25 μm/125-150 μm bimodal powder with fine powders content 35 mass% showed higher density and lower shrinkage ratio than those of other powder compacts. The improvement of particle packing depended strongly on the size ratio and mixing ratio of the fine to coarse powder.
