CeO_2对激光熔覆Ni基合金涂层组织与性能的影响

Effect of CeO_2 on Microstructure and Performance of Laser Cladding Ni-based Alloy Coatings

采用Nd:YAG激光器通过同步送粉方式,在20Cr2Ni4A钢基材上制备了添加一定稀土氧化物CeO2的Ni基合金熔覆层。通过扫描电镜、X射线能谱,分析研究添加的稀土对熔覆层组织形貌、元素分布的影响,用显微硬度计测量熔覆层的硬度分布。结果表明,CeO2的加入对镍基熔覆层的组织起到明显的细化和净化作用,使二次枝晶间距减小,夹杂物含量显著降低,枝晶生长的方向性减弱,组织趋向均匀;由于硬质相的析出和细晶强化的作用,熔覆涂层的显微硬度值比未添加稀土的涂层提高了40～70HV。

The nickel-based alloy coating with addition of 1.5 % CeO2 was cladded on the surface of 20Cr2Ni4A steel substrate by a Nd ： YAG laser with automatic powder feeding system. The microstructure and elements distribution of the coating were investigated by scanning electron microscope （SEM） and energy-dispersive analysis of X-ray （EDAX） respectively. The microhardness was measured by a microhardness tester. The results showed that the microstructure of coating with addition of CeO2 was obviously refined and purified, the spacing of second dendrites was greatly reduced, the content of inclusion was diminished and the growing direction of dendrites became weakened, the microstructure became uniform. As a result of hard phase precipitation and grain refining strengthening, the microhardness of the coatings with addition of CeO2 was increased 40- 70 HV compared with that of the coating without CeO2.