Abstract High-entropy alloys (HEAs) strengthened by coherent nanoparticles show great potentials for elevated-temperature structural applications, which however, generally suffer from a severe intergranular embrittlement when tested at intermediate temperatures. In this study, we demonstrated a novel “heterogenous columnar-grained” (HCG) approach that can effectively overcome this thorny problem. Different from the equiaxed counterpart which shows extreme brittleness along grain boundaries at 800 °C, the newly developed HCG-HEA exhibits an exceptionally high resistance to intergranular fractures originating from the unique grain-boundary characters and distributions. The presence of heterogenous columnar grain structure drastically suppresses the crack nucleation and propagation along with boundaries, resulting in an unusually large tensile ductility of ~18.4 % combined with a high yield strength of ~652 MPa at 800 °C. This finding provides a new insight into the innovative design of high-temperature materials with extraordinary mechanical properties.

中文翻译：

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非均质柱状晶高熵合金对中温晶间脆化具有出色的抵抗力

摘要 由相干纳米粒子强化的高熵合金 (HEAs) 在高温结构应用中显示出巨大的潜力，但在中等温度下测试时，通常会出现严重的晶间脆化。在这项研究中，我们展示了一种新颖的“异质柱状晶粒”（HCG）方法，可以有效地克服这个棘手的问题。与在 800 °C 下沿晶界显示出极端脆性的等轴对应物不同，新开发的 HCG-HEA 对源自独特的晶界特征和分布的晶间断裂具有极高的抵抗力。异质柱状晶粒结构的存在极大地抑制了裂纹的形核和沿边界的扩展，导致异常大的拉伸延展性达到 ~18.4%，并在 800°C 下具有 ~652 MPa 的高屈服强度。这一发现为具有非凡机械性能的高温材料的创新设计提供了新的见解。