(1. 东北大学 材料与冶金学院， 沈阳 110004；
2. 沈阳工业大学 材料科学与工程学院， 沈阳 110023)
摘 要: 采用稀土变质及激光熔覆工艺在20号钢基体上获得了钴基自熔合金梯度组织涂层。结果表明，204Co合金涂层组织为均匀的亚共晶，其组成相包括ε-Co，Co3B，M23(C，B)6，Cr2B及Co7W6化合物，平均硬度为HV1070，比基体(HV180)高HV890，耐磨性与基体相比提高1.5倍。在204Co合金中加入0.6%的稀土，可以获得梯度涂层。其组织由亚共晶向共晶连续过度，与前者相比，组成相增加了CeCr2B4，最高硬度达HV1204，比原合金高12.3%，耐磨性与基体相比提高近2倍，比原合金提高了25％。
关键字: 稀土；激光熔覆；钴基合金；梯度涂层
Co-based alloy with rare earth by
laser cladding
（1. School of Materials and Metallurgy，Northeastern University，
Shenyang 110004，China;
2. College of Materials Science and Engineering，
Shenyang Polytechnic University，Shenyang 110023，China）
Abstract:A method was approached about making a gradient coating of self-melt Co-based alloy on 20 steel substrate with rare earth(RE) by laser cladding. The results show that the coating with 204 Co alloy is a homogeneous sub-eutectic structure，which consists of ε-Co，Co3B，M23(C，B)6，Cr2B and Co7W6. The average hardness is HV1070，HV890 higher than that of the substrate (HV180). And the w ear resistance of the layer is found to be increased 1.5 times that of the base. When 0.6% RE is added into the 204Co alloy，the coating microstructure reveals agradient variation with the layer depth. The microstructure varies continuously from sub-eutectic to eutectic. Apart from the phases contained in the 204Co coating above，this coating still contains CeCr2B4. The highest hardness of the coating is HV1204，increasing 12.3% than that of 204Co alloy. The wear resistance is found to be increased about 2 times than that of the base and to be 25% higher than that of the 204Co alloy. The mechanism of forming gradient structure was discussed.
Key words: rare earth；laser cladding；Co-based alloy；gradient coating
