Improving Cyclic Oxidation Resistance of Additively Manufactured IN939 Superalloy via Chemical Vapor Aluminizing

Additively manufactured IN939 (AM-IN939) is promising for aeroengine turbine blades, where high-temperature oxidation resistance is essential. This study aims to enhance AM-IN939's high-temperature cyclic oxidation performance by applying nickel aluminide (NiAl) coating via the chemical vapor aluminizing process. Cyclic oxidation tests at 1050 degrees C for 240 cycles show a stable alpha-Al2O3 layer on NiAl-coated specimens, leading to weight gain due to its protective properties. Uncoated specimens form nonprotective oxides, including Cr2O3, TiO2, CoCr2O4, and NiCr2O4, resulting in weight loss from spallation, with internal oxidation and nitridation observed. Overall, the NiAl coating significantly enhances the high-temperature cyclic oxidation resistance of AM-IN939.