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- Effect of Compositional Trade-off Between Cr and Mo on the Corrosion Resistance of Additively Manufactured Co-Cr-Fe-Ni-Mo High-Entropy Alloys
- Jeongmin Lee, Yeonghwan Song, Jae Hyuk Lee, Sung-Jae Jo, Minho Shin, Hyunbin Lim, Soon-Jik Hong, Soo-Hyun Joo
- J Powder Mater. 2026;33(2):137-144. Published online April 30, 2026
- DOI: https://doi.org/10.4150/jpm.2026.00087
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Abstract
PDF - In this study, the corrosion behavior of Co-Cr-Fe-Ni-Mo high-entropy alloys additively manufactured via direct energy deposition was investigated according to the compositional trade-off between Cr and Mo elements. Two distinct alloy compositions were fabricated by adjusting the feeding rate of two powders with different chemical compositions through a dual nozzle. Electrochemical testing in a 3.5 wt% NaCl solution revealed that the Cr-rich and Mo-lean alloy exhibited inferior corrosion resistance compared to the Cr-lean and Mo-rich alloy. Specifically, the corrosion potential of the Cr-rich and Mo-lean alloy shifted negatively by approximately 200 mV compared to the Cr-lean and Mo-rich alloy, accompanied by an increase in corrosion current density and the pronounced initiation of localized pitting. This deterioration is attributed to a lack of passivation caused by the small amount of Mo in the Cr-rich and Mo-lean alloy. The passive film of the Cr-lean and Mo-rich alloy was more robust, characterized by a higher concentration of Mo, which effectively inhibited pit propagation through repassivation. These findings demonstrate that maintaining a critical Cr-Mo balance is more vital for the electrochemical stability of additively manufactured high-entropy alloys than unilateral Cr enrichment.
- [English]
- Ultrasonic Nanocrystal Surface Modification of 3D Interconnected Heterostructured Complex Concentrated Alloys Produced by Liquid Metal Dealloying: Microstructural Evolution and Wear Behavior
- Jumi Choi, Yeji Kim, Munsu Choi, Jae Hyuk Lee, Dong Jun Lee, Auezhan Amanov, Soo-Hyun Joo, Hyoung Seop Kim
- J Powder Mater. 2026;33(2):91-103. Published online April 30, 2026
- DOI: https://doi.org/10.4150/jpm.2026.00045
- 696 View
- 11 Download
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Abstract
PDF
- This study investigates the effects of ultrasonic nanocrystal surface modification (UNSM) on the microstructural evolution and tribological performance of a three-dimensional interconnected heterostructured compositionally complex alloy fabricated by liquid metal dealloying (LMD). The as-LMD microstructure comprises an interconnected Cu-rich phase and a CoCrFe-rich ligament phase. Electron backscatter diffraction reveals pronounced severe plastic deformation near the surface after UNSM, characterized by subgrain formation and increased intragranular misorientation. The kernel average misorientation distribution reveals a pronounced depth-dependent deformation gradient, with dislocations preferentially accumulating at the interphase boundaries. Vickers hardness increases from approximately 100–120 HV in the as-LMD condition to greater than 270 HV at the surface after UNSM, and the hardening effect remains detectable to a depth of approximately 500 μm. Compressive residual stresses are concentrated within the surface-adjacent ~50 μm. The solid ligament phase exhibits higher compressive residual stress than the Cu-rich phase, reflecting phase-dependent deformation accommodation and stress partitioning. Reciprocating wear tests show a narrower wear track, a markedly reduced wear depth, and a lower and more stable friction coefficient after UNSM. Microscopy shows oxide-layer cracking and delamination in the as-LMD condition, whereas the UNSM-treated surface exhibits minor abrasive wear of the tribo-film without delamination.
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