CrMnFeCoNi high-entropy alloys(HEAs)exhibit an excellent combination of tensile strength and ductility at cryogenic temperatures.This study led to the introduction of a new method for the development of high-performance CrMnFeCoNi HEAs at cryogenic temperatures by jointly utilizing additive manufactur-ing(AM)and the addition of interstitial atoms.The interstitial oxygen present in the powder feedstock was transformed into beneficial nano-sized oxides during AM processing.The HEA nanocomposite fab-ricated using laser powder bed fusion(L-PBF)not only contains heterogeneous grains and substructures but also a high number density of nano-sized oxides.The tensile results revealed that the L-PBF HEA nanocomposite has superior yield strengths of 0.77 GPa and 1.15 GPa,and tensile strengths of 0.92 GPa and 1.45 GPa at 298 K and 77 K,respectively.In addition,the Charpy impact energies of the samples tested at 298 K and 77 K were measured as 176.2 J and 103.7 J,respectively.These results indicate that the L-PBF HEA nanocomposite successfully overcomes the well-known strength-toughness trade-off.The tensile deformation microstructure contained a relatively large number of deformation twins(DTs)at cryogenic temperature,a possible consequence of the decrease in the stacking fault energy with decreas-ing temperature.On the other hand,cracks were found to propagate along the grain boundaries at room temperature,whereas a transgranular crack was observed at cryogenic temperature in the specimens fractured as a result of the Charpy impact.

Young-Kyun Kim;Min-Chul Kim;Kee-Ahn Lee

Department of Materials Science and Engineering,Inha University,Incheon 22212,Republic of Korea;Korea Atomic Energy Research Institute(KAERI),Daejeon 34057,Republic of Korea

材料科学技术（英文版）

[1]Young-Kyun Kim;Min-Chul Kim;Kee-Ahn Lee-.1.45 GPa ultrastrong cryogenic strength with superior impact toughness in the in-situ nano oxide reinforced CrMnFeCoNi high-entropy alloy matrix nanocomposite manufactured by laser powder bed fusion)[J].材料科学技术（英文版）,2022(02):10-19

ultrastrong,decreas

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