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LPBF High-Strength, Crack-Free CoCrNi Matrix Composite Developed via Grain Boundary Segregation Design at University of South China
2026-06-29
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Impact score: 24
A research team from the University of South China, in collaboration with the Leibniz Institute for Solid State and Materials Research in Germany and the Harbin Institute of Technology, has developed a high-performance CoCrNi-based composite tailored for additive manufacturing using a grain boundary segregation design. By introducing micron-sized TiC particles via laser powder bed fusion (LPBF), the team produced crack-free, high-strength CoCrNi medium-entropy alloys. Mechanistic studies show that TiC addition promotes carbon segregation to grain boundaries, significantly lowering grain boundary energy and effectively suppressing hot cracking. During LPBF, partial dissolution of TiC forms nano-scale Cr23C6 precipitates and TiC/TiO₂ core-shell structures, refining the grain size. The CoCrNi-3 wt% TiC composite exhibits excellent mechanical properties and high-temperature oxidation resistance, with the fine-grained microstructure facilitating the formation of a dense Cr₂O₃ protective layer. This work provides a new theoretical framework for designing high-performance alloys for additive manufacturing.
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南华大学开发基于晶界偏析的CoCrNi基复合材料，实现LPBF无裂纹高强度打印
南华大学联合德国莱布尼茨固体与材料研究所和哈尔滨工业大学的研究团队，开发了一种基于晶界偏析设计、适用于增材制造的高性能CoCrNi基复合材料。研究团队采用激光粉末床熔融技术，通过引入微米级TiC颗粒，成功制备了无裂纹、高强度的CoCrNi中熵合金。机理研究表明，TiC的引入促进了碳原子向晶界偏析，显著降低了晶界能，有效抑制了热裂纹的形成；同时，PBF-LB过程中TiC部分溶解形成纳米级Cr23C6析出物和TiC/TiO2核壳结构，细化了晶粒。CoCrNi-3 wt% TiC复合材料表现出优异的力学性能和高温抗氧化性能，细晶组织促进了致密Cr2O3保护膜的形成。该研究为增材制造高性能合金的设计提供了新的理论框架。