Lattice distortion, which is intended to increase the yield strengths of alloys, is central to alloy design. This study focuses on investigating the close connection between microstructure and mechanical properties of (CoNiV)₉₇Al₃ medium-entropy alloys (MEAs) in the as-cast and annealed states. The grain size and phase composition of the alloys were optimized by combining the large deformation cold-rolling and high temperature annealing treatment, and the toughening mechanism of the alloys was evolved. After annealing at 900 and 950°C, a small amount of diffuse B2 phase appears within the alloy, which is able to strengthen the alloy to obtain high yield strength. Since intermetallic compounds such as Ni3Al are extremely unstable, they will decompose during annealing at higher temperature (1000°C), the alloy transforms into a single FCC phase. Therefore, the as-cast and annealed (CoNiV)₉₇Al₃ alloy exhibited excellent mechanical properties, including yield strengths of 0.8–1.1 GPa, ultimate tensile strengths of 1.05–1.7 GPa, and an optimal elongation of 36.7%. Combined with the mechanical properties and microstructure of the as-cast and annealed (CoNiV)₉₇Al₃ MEAs, the alloy strengthening was mainly attributed to the synergistic effect of dislocations, solid solution phases, and B2 brittle precipitated phases, while the good ductility was mainly due to the annealing twins. Thus, harmonizing multiple strength/toughness mechanisms can lead to a more optimal alloy strength–plasticity equilibrium point.

中文翻译：

---

添加 Al 的铸态和退火 CoNiV 基膜电极的微观结构和力学性能


晶格畸变旨在提高合金的屈服强度，是合金设计的核心。本研究重点研究了 （CoNiV）₉₇Al₃ 中等熵合金 （MEA） 在铸态和退火状态下的微观组织与机械性能之间的密切联系。通过结合大变形冷轧和高温退火处理，优化了合金的晶粒尺寸和物相组成，并发展了合金的增韧机理。在 900°C 和 950°C 退火后，合金内部出现少量弥漫性 B2 相，能够强化合金以获得高屈服强度。由于 Ni3Al 等金属间化合物极不稳定，它们在较高温度 （1000°C） 退火过程中会分解，合金转变为单个 FCC 相。因此，铸态和退火 （CoNiV）₉₇Al₃ 合金表现出优异的机械性能，包括 0.8-1.1GPa 的屈服强度、1.05-1.7GPa 的极限抗拉强度和 36.7% 的最佳伸长率。结合铸态和退火 （CoNiV）₉₇Al₃ MEAs 的力学性能和微观组织，合金强化主要归因于位错、固溶相和 B2 脆性沉淀相的协同作用，而良好的延展性主要归因于退火孪晶。因此，协调多种强度/韧性机制可以产生更优化的合金强度-塑性平衡点。