Ni-WC表面合金化45钢基复合材料的组织观察

Observation of Microstructures of Ni-WC Alloyed 45 Cast Steel Matrix Surface Composites

以Ni-WC粉末为主要原料制成涂料涂覆在EPS泡沫塑料模样的表面上,采用V-EPC真空消失模铸造方法浇注45钢液,制备出Ni-WC表面合金化45钢基复合材料。应用光学显微镜、SEM、EDS和XRD观察和分析了复合材料的显微组织。结果表明,复合材料由表面复合层、中间过渡层和内部基体3个区域组成。在表面复合层中,Ni-WC颗粒已全部发生分解,其组织由少量的细小条状的富钨碳化物、大量的粗大网状碳化物和树枝晶基体组成;过渡层在靠近表面复合层一侧有一条全部由极细珠光体组成的窄带,而在靠近基体区域一侧组织由块状的铁素体和珠光体组成,并且在这些晶粒内部和晶界上都可以观察到有碳化物析出;基体区域组织形貌与常规45钢相似,但组织中珠光体含量明显高一些。

The EPS samples that are mainly consisted of Ni-WC powders are prepared.The samples are then cast with 45 cast steel using V-EPC casting infiltration technique,forming the Ni-WC alloyed 45 cast steel matrix surface composites.The microstructures are observed and analyzed using optical microscope,SEM,EDS and XRD.The results show that the composites from surface to core are obviously consisted of three different microstructural zones,the top alloyed surface layer,the transitional layer and the matrix zone.There are no any Ni-WC particles existed in the alloyed surface layer and the microstructures in this layer are consisted of a small amount of W rich fine carbides,a large amount of net big carbides and dendritic matrix.There is a narrow pearlites strip near the alloyed surface layer and the microstructures from the strip to core turned to mixture of ferrite and pearlites in the transitional layer.Some amounts of carbide particles precipitation can be observed within the matrix grains and in the matrix grain boundaries in this layer.The microstructures in the matrix are quite similar to the conventional 45 steel,but the amounts of pearlites seem to be higher than that of the conventional one.