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

Defect free coatings of Høganäs 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.