By means of adding an Fe-23Si alloy (Fe5Sia) into Fe powders and sintering them in the atmosphere of ordinary cylindered H2 gas, Fe-Si system sintered compacts which have excellent mechanical properties were obtained.
As a result of consideration of relations between aspects of alloying of Si and mechanical properties of sintered compacts, it was made clear that a large "expansion" based on alloying of Si into Fe and a large "shrinkage" based on a phase-sintering cause spheroidizing of residual porosity in the structure and an extreme improvement of mechanical properties.