Abstract CrCoNi exhibits the best combination of strength and ductility among all the equiatomic single-phase FCC subsets of the CrMnFeCoNi high-entropy alloy. Here, its yield strength was determined in compression as a function of grain size and temperature. Yield strength was also plotted as a function of “crystallite” size, which takes into account both annealing twin boundaries and grain boundaries. The resulting Hall-Petch slopes were straight lines but with different slopes that depend on the number of twin boundaries per grain. Scanning transmission electron microscopy of deformed specimens revealed the formation of dislocation pile-ups at grain and annealing twin boundaries indicating that the latter also act as obstacles to slip and contribute to strength. Using a simple pile-up model, the strengths of the grain and twin boundaries were estimated to lie in the range 900–1250 MPa. Assuming that they have the same strength, in the case of twin boundaries this strength corresponds roughly to the stress required to constrict Shockley partials, which suggests that dissociated dislocations have to become compact before they can cross the annealing twin boundaries.

中文翻译：

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CrCoNi中熵合金晶界和退火孪晶界强化分析

摘要 在 CrMnFeCoNi 高熵合金的所有等原子单相 FCC 子集中，CrCoNi 表现出最佳的强度和延展性组合。在这里，它的屈服强度是在压缩时作为晶粒尺寸和温度的函数来确定的。屈服强度也被绘制为“微晶”尺寸的函数，它考虑了退火孪晶界和晶界。由此产生的 Hall-Petch 斜率是直线，但具有不同的斜率，这取决于每个晶粒的孪晶界数。变形试样的扫描透射电子显微镜显示在晶粒和退火孪晶边界处形成位错堆积，表明后者也作为滑动障碍并有助于强度。使用简单的堆积模型，晶界和孪晶界的强度估计在 900-1250 MPa 范围内。假设它们具有相同的强度，在孪晶边界的情况下，该强度大致对应于收缩肖克利部分所需的应力，这表明解离位错在它们可以穿过退火孪晶边界之前必须变得紧密。