材料科学
晶界
脆性
脆化
晶间腐蚀
冶金
穿晶断裂
脆性断裂
合金
高熵合金
晶间断裂
软化
断裂(地质)
复合材料
微观结构
作者
Zhengqi Wang,Hong‐Hui Wu,Yuan Wu,Xiangyu Zhu,Yingjie Zhang,Huihui Zhu,Xiaoyuan Yuan,Qiang Chen,Shudao Wang,Xiong‐Jun Liu,Hui Wang,Suihe Jiang,Moon Kim,Xiongjun Liu
标识
DOI:10.1016/j.mattod.2022.02.006
摘要
Refractory high-entropy alloys (RHEAs), particularly NbMoTaW RHEAs, exhibit outstanding softening resistance and thermal stability at ultra-high temperatures, but suffer from room-temperature brittleness, which severely limits their processability and thus practical application. In this study, we successfully achieved large plasticity of >10%, along with high strength of >1750 MPa in the NbMoTaW RHEAs via grain boundary engineering with the addition of either metalloid B or C. It was revealed that the room-temperature brittleness of the as-cast NbMoTaW RHEA originates from the grain-boundary segregation of the oxygen contaminant which weakens grain-boundary cohesion. The doped small-sized metalloids preferentially replace oxygen at grain boundaries and promote stronger electronic interaction with the host metals, which effectively alleviates the grain boundary brittleness and changes the fracture morphology from intergranular fracture to transgranular fracture. Our findings not only shed light on the understanding of the embrittlement mechanism of RHEAs in general, but also offer a useful route for ductilization of brittle HEAs.
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