Additive manufacturing makes it possible to improve the mechanical properties of alloys through segregation engineering of specific alloying elements into the dislocation cell structure. In this study, we investigated the mechanical and microstructural characteristics of CoNi-based medium-entropy alloys (MEAs), including the refractory alloying element Mo with a large atomic radius, manufactured via laser-powder bed fusion (L-PBF). In an analysis of the printability depending on the processing parameters, we achieved a high compressive yield strength up to 653 MPa in L-PBF for (CoNi)85Mo15 MEAs. However, severe residual stress remained at high-angle grain boundaries, and a brittle μ phase was precipitated at Mo-segregated dislocation cells. These resulted in hot-cracking behaviors in (CoNi)85Mo15 MEAs during L-PBF. These findings highlight the need for further research to adjust the Mo content and processing techniques to mitigate cracking behaviors in L-PBF-manufactured (CoNi)85Mo15 MEAs.

1. Introduction 
2. Experimental procedure 
3. Results and Discussion 
4. Conclusion 
Funding
Conflict of Interest  
Data Availability Statement 
Author Information and Contribution 
Acknowledgement
References

• Seungjin Nam(Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea)
• Heechan Jung(Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea)
• Chahee Jung(Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea)
• Seok Su Sohn(Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea, Department of Advanced Future Convergence Materials, Korea University, Seoul 02841, Republic of Korea) Corresponding author
• Haeum Park(Department of Advanced Future Convergence Materials, Korea University, Seoul 02841, Republic of Korea, Department of 3D Printing Materials, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea)
• Jeong Min Park(Department of 3D Printing Materials, Korea Institute of Materials Science (KIMS), Changwon 51508, Republic of Korea)
• Hyoung Seop Kim(Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea, Graduate Institute of Ferrous and Eco Materials Technology, Pohang University of Science and Technology, Pohang 37673, Republic of Korea, Center for Heterogenic Metal Additive Manufacturing, Pohang University of Science and Technology, Pohang 37673, Republic of Korea 7Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan, Institute for Convergence Research and Education in Advanced Technology, Yonsei University, Seoul 03722, Republic of Korea)