Effect of pore structure on the impact toughness of copper-infiltrated sintered steel

Copper-infiltrated sintered steel is a prominent area of research in powder metallurgy, with a particular focus on enhancing impact toughness. In this study, sintered steels with varying pore structures were prepared using iron powders and infiltrated with copper to investigate their impact toughness. The results indicate a significant improvement in the impact toughness of the sintered steels with concentrated iron particle sizes. The density of the samples increased from 6.85 g cm-3 to 7.55 g cm-3 through copper infiltration. The large copper-phase sample with the particle size of 150 mu m exhibits an impact toughness as high as 41.09 J cm-2, and its fracture morphology mainly shows transgranular fractures of large iron particles. It is 1.5 times that of the sample made from commercial iron powders which measured 27.46 J cm-2. This enhancement is primarily attributed to the precipitation of gamma-Fe within the large copper phase, thereby enhancing the copper phase and transferring the load into large iron particles. A brief mechanism of gamma-Fe precipitation in the large copper-phase has been provided.