Oxidation behavior of hastelloy X alloy fabricated by selective laser melting and subsequent hot isostatic pressing treatment

Hastelloy X is a typical solid solution strengthening superalloy featured by good tolerance against oxidation and adequate mechanical and creep properties at 900 °C. However, current works about Ni-based superalloys mainly focus on the relationship between microstructure and mechanical performance at high-temperature regions, leaving the failure mechanism under the circumstance of oxidation as an open issue. Herein, the effects of the microstructure on the high-temperature oxidation behavior and mechanical properties of Hastelloy X alloys prepared by selective laser melting (SLM) technique and hot isostatic pressing (HIP), respectively, are investigated. The experimental results show the existence of a large number of microcracks in the SLM samples during oxidation at 900 °C, which can contribute to increased oxidation weight gain and ease of oxide layer exfoliation. With the assistance of HIP, thermal cracks are effectively eliminated by the combination of better elemental homogeneity. The further improvement of oxidation resistance is found to result from the densification of Cr${}_2$O${}_3$ particles and the hindrance of oxygen diffusion. From the perspective of the application, this work provides valuable support for the explanations of the oxidation resistance and fracture mechanism of Hastelloy X superalloys in high-temperature service environments. (© 2022 Wiley‐VCH GmbH)