双层烧结铁基材料的制备及其组织性能

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

采用加压烧结工艺制备了双层烧结铁基材料,研究了合金元素对高合金层烧结致密化的影响及其在界面区的分布规律,分析了该材料的显微组织和力学性能。研究结果表明:提高C和Mo的含量有利于高合金层的致密化,而提高V含量阻碍其致密化。双层烧结铁基材料综合了高合金层和基体层的优点,抗弯强度达1 980 MPa,冲击韧性达18 J/cm2,洛氏硬度为50。高合金层呈脆性解理断裂,基体层呈韧性断裂;C和Mo和V在界面区的扩散受到抑制,其中Mo和V集中分布在碳化物中;Cr在界面区有一定程度的扩散,Cr在高合金层中的分布相对均匀。

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.