Oxide dispersion strengthening in CrCoNi medium entropy alloy built by selective laser melting with oxygen-rich powder

Abstract

In laser-based additive manufacturing for metallic materials, the high standard for alloy powder quality significantly increases cost, energy, and time consumption, which hinders further practical applications. In this study, we focus on the influence of oxygen impurity of the powder feedstock for the additive manufacturing approach of selective laser melting, using equimolar CrCoNi medium entropy alloy (MEA) as an example. We synthesized both pristine CrCoNi powder and its oxygen-rich counterpart (MEAO). We thoroughly characterized the microstructural evolution during tensile loading using a series of characterization methods, including XRD, SEM, EBSD, and TEM. The results revealed a well-preserved deformation mechanism of nano-twinning, along with elevated strength achieved by the oxide dispersion strengthening in the LPBF-built MEAO sample. This research demonstrates the potential for cost reduction in the powder fabricating process for additive manufacturing.