Repair of K403 Superalloy Damaged Blades by a Powder Metallurgy Method

The damaged K403 superalloy blades were repaired and remanufactured by a powder metallurgy repairing process(china powder metallurgy, CPM), using nickel-based superalloy powder containing a small amount of B alloy and nano-Ni powder separately. X-ray diffraction, scanning electronic microscope(SEM), EDX, and EPMA electro-probe were employed to investigate the phase composition, morphology and microstructure of the repaired areas. Meanwhile, performances of repairing areas and interface bonding were evaluated. Finally, the mechanism on the densification of repairing areas and the bonding of interface were also examined. The results show that the damaged blades could be restored to the original shape and size by CPM process, using appropriate repairing powder. In addition, it shows better properties using B alloy powder addition for K403 repairing. The diffusion of element B plays a key role in the densification of repairing areas and bonding of interface, in which the reaction equation could be expressed as Ni m B n+(Cr, W)→γ+(Cr2,W)B2. According to calculation, in the CPM process, the concentration of element B in the interface could be decreased to below the eutectic concentration.