Preparation and structure property of iron based material with two-layer structure

Iron based materials with two-layer structure were produced via powder metallurgy,which were sintered in vacuum atmosphere under certain pressure in order to keep shape.The influences of alloying element on the densification behavior of high alloy layer were discussed.The microstructure and mechanical properties of the material were also investigated.The results show that the density increases with the increment of C and Mo,but decreases sharply with the increases of V.It is proved that the mechanical properties of the two-layer structure can be improved a lot.The flexural strength reaches 1980 MPa,the impact energy is up to 18 J/cm~2 and the hardness achieves 50.In view of the feature of the fracture surface,the matrix shows obviously dimple feature while the fracture mode of high alloyed layer is brittle.The distribution maps of the alloying elements demonstrate that the diffusion of C,Mo and V is inhibited.This is attributed to the high potential of Mo and V to distribute in carbide.Cr is more homogeneous in the high alloy layer and it diffuses in the interface region.