Improved resistance to high-temperature oxidation in a fine-grained CrMnFeCoNi high-entropy alloy additively manufactured by laser powder bed fusion

The high-temperature oxidation behavior of a fine-grained CrMnFeCoNi high-entropy alloy (HEA) manufactured by laser powder bed fusion (LPBF) was investigated. The LPBF-built HEA exhibited heterogeneous, fine-grained structures with a single phase. In addition, substructures induced by dislocation networks and nanosized oxides were observed within the grains. The fine-grained structure had a positive effect on the resistance to high-temperature oxidation. Oxidation tests were conducted at 900 °C, 1000 °C, and 1100 °C for 24 h, and the L-PBF alloy exhibited significantly lower mass gains compared to its traditionally processed counterpart (THEA). Specifically, the mass gain of the L-PBF alloy were 1.43, 3.50, and 6.47 mg/cm 2 at 900, 1000, and 1100 °C, respectively, whereas the THEA sample showed 1.76, 4.45, and 9.09 mg/cm 2 . Moreover at 1000 °C, the internal oxide scale of the L-PBF alloy (∼50 μm) was approximately 60 % thinner than that of the THEA (∼130 μm). This refined microstructure promoted the formation of a stable and continuous Cr 2 O 3 scale and suppressed the formation of spinel phases, thereby enhancing high-temperature oxidation resistance. By comparing with the oxidation behaviors of HEAs produced by traditional manufacturing processes, we aimed to deepen our understanding of the high-temperature oxidation behavior of HEAs fabricated via the LPBF process. Based on these results, the mechanisms underlying the excellent oxidation resistance of the LPBF-built CrMnFeCoNi HEA are discussed in detail. • Fine-grained CrMnFeCoNi HEA manufactured by LPBF. • LPBF-built HEA demonstrates superior high temperature oxidation resistance compared to conventionally processed CrMnFeCoNi HEA. • The fine-grained structure of LPBF-built HEA plays a crucial role in oxidation resistance by rapid formation of a dense and continuous Cr 2 O 3 layer.