Characterization and growth kinetics of plasma nitrided layer fabricated on Incoloy 901 superalloy

Abstract

The phase composition, microstructure, mechanical performance and growth kinetics of nitrided layers on Incoloy 901 (IN-901) at 460– 610 °C were investigated. XRD results indicated that CrN, γ-FeNi, γN and Ni4N were the main phase compositions of the nitrided layer. The formation of Ni4N took longer duration or higher temperature than those of CrN and γN. EDS results suggested that the content of Cr in the nitrided layer was larger than that in the substrate, while fewer Ni and Fe entered the nitrided layer from the matrix. The kinetic studies showed that the weight and thickness of the nitrided layer significantly increased with the increase of nitriding temperature, and the diffusion activation energy of IN-901 was calculated as ~153 kJ/mol (1.6 eV). Micro-hardness and sliding tests proved a high surface hardness (up to ~1892 HV0.025) and a low friction coefficient (~0.22) of the nitrided IN-901.