Understanding phase stability of CoCrNi alloy is necessary to ensure that no detrimental phases form when held for long period of time during the potential application temperature

•A long-term annealing at 450 °C for 350 hrs was employed to explore the phase stability in a severely deformed CoCrNi with high density of GBs to facilitate any secondary phase formation

•Cr-rich oxides were observed at several GBs

•An elongated phase, rich in Co and depleted in Ni, at few GBs near the Cr-rich oxide. Electron diffraction pattern suggest that this phase has an HCP structure

•Microscopy experiments and high-throughput CALPHAD calculations suggest that local composition fluctuation near the Cr-rich oxide favors the HCP phase formation

Sakshi Bajpai¹, Xin Wang¹, Calvin H. Belcher¹, Benjamin E. MacDonald¹, Julia Ivanisenko², Horst Hahn², Yu Zhong³, Enrique J. Lavernia^1,4, Diran Apelian¹

¹ UC Irvine, ² Karlsruhe Institute of Technology, Germany, ³Worcester Polytechnic Institute, ⁴Texas A&M University