Ni基高温合金表面激光熔覆Co基合金的组织

Microstructure of Laser Cladding Co-based Alloy on Ni-based Superalloy

采用横流CO2 激光 ,在Ni基高温合金表面激光熔覆H gan sCo钴基非自熔性合金粉末 ,制备了无缺陷的涂层。利用光学显微镜、扫描电镜及附件 (EDS)、透射电镜(TEM)、X射线衍射仪分析了Co钴基合金熔覆层的组织结构 ,比较了熔覆层两道之间搭接重熔区与非重熔区的组织特征。结果表明 ,熔覆层的初生相为γ -Co枝晶 ,枝晶间为γ -Co +Cr2 3C6 共晶 ;熔覆层与基体交界具有快速定向凝固特征 ,晶粒生长方向为垂直于界面 ,而表层则倾向于平行激光扫描方向 ;

Defect free coatings of Hoganfls Co-based non-self-fluxing alloy deposited by crosscurrent CO2 laser on Ni-based superalloy are introduced. Section and remelted zone between two tracks of the coatings have been examined to reveal their microstructure and phase composition using optical microscope, SEM(including EDS microanalysis), XRD and TEM. The results showed that there were primary phase (γ-Co)and eutectic (γ-Co +Cr23C6)in the coatings. Rapid directional solidification was found at the interface where the growth direction was perpendicular to the interface. Multi-orientation and direction paralleling to the scanning speed were also found at the center area and near the top surface correspondingly. A novel microstructure was found to transmit the crystallization direction of the first layer at the remelted boundary between two tracks.