TY  - EJOU
AU  - Lee, Kee-Ahn 
AU  - Park, So-Yeon 
AU  - Kim, Soo-Bin 
AU  - Kim, Young-Kyun 

TI  - In-Situ Carbide-Reinforced NiCoCr Medium-Entropy Alloy Manufactured by Laser Powder Bed Fusion; Fabrication, Microstructure, Mechanical Property, and High Temperature Oxidation Behavior
T2  - The International Conference on Computational \& Experimental Engineering and Sciences

PY  - 2024
VL  - 31
IS  - 4
SN  - 1933-2815

AB  - NiCoCr medium-entropy alloys (MEAs) with controlled interstitial C contents were fabricated by using powder bed fusion-type additive manufacturing (AM) process. And the microstructure, mechanical properties, and high temperature oxidation resistance of in-situ carbide-reinforced NiCoCr Medium alloy were investigated. The initial microstructure shows that both AM-built interstitial C-doped MEAs had a heterogeneous grain structure and epitaxial growth grains along the building direction. The analysis of electron channeling contrast images showed a large amount of nano-sized precipitates (in-situ precipitates) distributed at the sub-structure boundaries formed by a dislocation network, and a large number of stacking faults were simultaneously observed inside the sub-structure. A room temperature tensile tests indicated the highest properties among additively manufactured MEAs reported to date. After heat treatment process, the size and ratio of nano-sized precipitates enhanced and identified as Cr-rich M<sub>23</sub>C<sub>6</sub> carbide. The yield and tensile strengths increase after heat treatment, which is attributed to the prevailing solid solution strengthening and precipitation strengthening. In the C-dopped MEA fabricated by L-PBF, Cr-rich M23C6 is formed along the sub-grain boundaries, and carbide oxidation occurs due to high temperature oxidation exposure. Based on the above results, the deformation and high temperature oxidation mechanisms of AM-built interstitial NiCoCr MEA were also discussed.
KW  - Medium entropy alloy; NiCoCr; carbon content; microstructure; mechanical property; high temperature oxidation

DO  - 10.32604/icces.2024.012196