effect of yb-yag laser parameters on the operating regime of plasma sprayed nicraly premixed coatings

The direct laser melting of plasma sprayed bond coat has the possibility of improving the surface topography and can be done with yb:yag laser. in the current paper, laser melting of plasma sprayed coatings of 50 wt. % standard amdry 963 (ni24.5cr6al0.4y) and 50 wt. % standard amdry 9621 (ni22cr10aly) was carried out by using 600 w continuous wave yb:yag laser. notably, the obtained melted tracks were investigated from the upper surface plan view and transverse section. the topography, microstructure, phases, hardness, and compositions of the plasma sprayed coatings and laser-remelted tracks were characterized by scanning electron microscopy (sem), energy-dispersive x-ray spectroscopy (eds), x-ray diffraction (xrd), roughness, and microhardness. by controlling the dependent laser variables  (power density and interaction time), a different effect can be obtained for the plasma sprayed bond coating (nicraly). typically, the results obtained show that at low specific energies, four different distinct zones were observed. these specific energies were not sufficient to produce a uniform melting. the mcraly coatings remelted with high specific energies were characterized by completely uniform melting and cellular/dendritic microstructures. the melted coatings have high roughness reduction (1.2 μm) and low hardness (275 hv0.5) in comparison with plasma-sprayed coatings (10.5 μm) and (315 hv0.5) respectively.