Effect of Vacuum Carburizing on the Structure and the Properties of Aluminide Coatings on Nickel Superalloys

The processes that occur during vacuum carburizing of turbine blades made of carbon-free nickel superalloys are considered. Disperse alloying-element carbide particles are found to form in the surface layer of the VZhM5 alloy. These particles increase the fatigue life of the alloy during high-temperature oxidation. The disperse carbide particles are shown to hinder the formation of coarse γ′-Ni₃Al grains and topologically close-packed phases under a coating; hence, they prevent premature fracture of the alloy.