Precipitation engineering is one of the most effective means to enhance the strength of an alloy, which essentially requires precipitates with certain deformability, fine size, and uniform distribution. However, for multicomponent alloy systems, the chemical complexity poses significant difficulties in applying this strengthening method due to the diversity and brittleness of the potential precipitate phases. In this work, we demonstrated the precipitation engineering in a chemically complex prototype alloy NiCoV. Specifically, formation of detrimental σ, μ and Heusler phases was avoided by reducing the V content, and a two-step short-term annealing was designed to trigger homogeneous κ nucleation while inhibiting its rapid coarsening. It is found that both grain and phase boundaries can trap V atoms, which not only pins these interfaces but also hinders the V partitioning needed for κ growth. Consequently, we achieved an ultrafine κ/γ architecture in the NiCoV0.9 alloy, which surprisingly exhibited an ultrahigh yield strength of 1.6 GPa and a total work-hardening amount of 219 MPa. Our analysis indicates that the hetero-deformation induced (HDI) stress is mainly responsible for the high strength, while the coherent nature of phase boundaries and decent deformability of κ alleviate stress concentration, giving rise to the pronounced work-hardening. Our work highlights the importance of suitable phase selection and delicate substructure tailoring in precipitation engineering, with key findings also useful for enhancing overall mechanical properties in other multicomponent alloys.

中文翻译：

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通过沉淀工程显著提高 NiCoV 中等熵合金的力学性能


沉淀工程是提高合金强度的最有效手段之一，它本质上需要具有一定变形能力、细小尺寸和分布均匀的析出物。然而，对于多组分合金系统，由于潜在沉淀相的多样性和脆性，化学复杂性给应用这种强化方法带来了重大困难。在这项工作中，我们展示了化学复杂的原型合金 NiCoV 中的沉淀工程。具体来说，通过降低 V 含量避免了有害 σ、μ 和 Heusler 相的形成，并设计了两步短时退火以触发均匀的 κ 成核，同时抑制其快速粗化。研究发现晶界和相界都可以捕获 V 原子，这不仅固定了这些界面，还阻碍了 κ 生长所需的 V 分配。因此，我们在 NiCoV0.9 合金中实现了超细 κ/γ 结构，令人惊讶地表现出 1.6 GPa 的超高屈服强度和 219 MPa 的总加工硬化量。分析表明，异质变形诱导 （HDI） 应力是高强度的主要原因，而相界的连贯性和 κ 的良好变形能力减轻了应力集中，从而引起了明显的加工硬化。我们的工作强调了沉淀工程中合适的相选择和精细的子结构定制的重要性，关键发现也有助于提高其他多组分合金的整体机械性能。