Oxidation of additively manufactured Ni-base alloy IN625: Mechanism of intergranular oxidation

Journal article, 2025

The oxidation resistance of additively manufactured (AM) Ni-base alloy Inconel 625 (IN625) has been evaluated in air at 900 °C and compared with that of the conventionally manufactured (CM) forged alloy. The AM alloy suffered from intergranular oxidation (IGO) in contrast to CM. The Cr2O3 scales thermally grown on both CM and AM were analyzed with SEM/EDX, EBSD, GD-OES, TEM and APT. A new mechanism of IGO in AM alloys is proposed. Oxide scale decohesion over the alloy grain boundaries is believed to be the key trigger of IGO originating from minor differences in the alloy compositions (Al, Mn, Si, Ti) between AM and CM, rather than the AM process itself.