Improvement in corrosion and wear resistance of Ni3Al-based superalloy coatings through laser energy density regulation

In this study, the laser energy densities ( L ed ) have a significant impact on microstructure and properties of Ni 3 Al-based superalloy (IC-221 M) coatings produced via laser cladding. The high-energy laser beam induces a substantial temperature gradient, leading to epitaxial growth and a transition from columnar to equiaxed grains at the top due to equiaxed nucleation impeding further columnar growth. A combination of molten pool thermodynamic simulations and experiments was employed to further investigate the CET behavior, and the calculated density of nucleation sites ( N 0 ) could be further utilized to guide process planning. Notably, under the condition of L ed = 65 J/mm 2 , the IC-221 M coating near the surface generates a finer grain structure, which hinders pitting corrosion and improves corrosion resistance. The optimal L ed results in a minimal corrosion current density of 3.79 × 10 −6 A/cm 2 and an increased charge transfer resistance ( R ct ) of 28,160 Ω cm 2 . The refined grain structure significantly enhances the strength and shear resistance, achieving a wear rate of 7.34 × 10 −5 mm 3 /Nm at 600 °C. Surface oxide particles act as a lubricant, reducing the average coefficient of friction to 0.3705. The study highlights the importance of precise L ed control for optimizing the properties of IC-221 M superalloy coatings in harsh environments.