Precipitation at grain boundaries is typically not regarded as an efficient method for strengthening materials since it can induce grain boundary embrittlement, which detrimentally affects ductility. In this research, we developed a multi-principal element alloy (MPEA) with the composition CrCoNiAlTi (at.%), incorporating both intragranular and intergranular nanoprecipitates. Utilizing multiscale, three-dimensional, and electron microscopy techniques, coupled with computational simulations, we established that intergranular nanoprecipitation in this material plays a crucial role in enhancing strength and promoting dislocation plasticity. The structure of intergranular nanoprecipitation comprises multiple phases with varying composition and structure. Despite the diversity, the crystal planes conducive to the easy glide of dislocations are well-matched, allowing for the sustained continuity of dislocation slipping across different phase structures. Simultaneously, this structure generates an undulated stress field near grain boundaries, amplifying the strengthening effect and facilitating multiple slip and cross-slip during deformation. Consequently, it promotes the proliferation and storage of dislocations. As a result, our material exhibits a yield strength of approximately 1010 MPa and an ultimate tensile strength of around 1500 MPa, accompanied by a significant fracture elongation of 41 %. Our findings illuminate the potential for harnessing intergranular nanoprecipitation to optimize the strength-ductility trade-off in MPEAs, emphasizing the strategy of leveraging complex compositions for the design of sophisticated functional microstructures.

中文翻译：

---

通过晶间析出实现 Cr30Co30Ni30Al5Ti5 合金的高强度和大塑性


晶界沉淀通常不被认为是强化材料的有效方法，因为它会引起晶界脆化，从而对延展性产生不利影响。在这项研究中，我们开发了一种成分为 CrCoNiAlTi (at.%) 的多主元素合金 (MPEA)，其中包含晶内和晶间纳米沉淀物。利用多尺度、三维和电子显微镜技术，结合计算模拟，我们确定这种材料中的晶间纳米沉淀在增强强度和促进位错塑性方面发挥着至关重要的作用。粒间纳米沉淀的结构包括具有不同组成和结构的多个相。尽管存在多样性，但有利于位错轻松滑动的晶面是良好匹配的，从而允许位错在不同相结构上滑动的持续连续性。同时，这种结构在晶界附近产生波状应力场，放大强化效果并促进变形过程中的多重滑移和交叉滑移。因此，它促进了位错的扩散和存储。因此，我们的材料表现出约 1010 MPa 的屈服强度和约 1500 MPa 的极限拉伸强度，同时断裂伸长率高达 41%。我们的研究结果阐明了利用晶间纳米沉淀来优化 MPEA 的强度-延展性权衡的潜力，强调了利用复杂成分来设计复杂功能微结构的策略。