Forced mixing to a single-phase or supersaturated solid solution (SSS) and its prerequisite microstructure evolution in immiscible systems has been a focus of research for fundamental science and practical applications. Controlling the formation of SSS by shear deformation could enable a material design beyond conventional equilibrium microstructure in immiscible systems. Here, a highly immiscible Cu–50 at.% Cr binary alloy (mixing enthalpy of ∼20 kJ mol⁻¹) was employed to investigate the microstructure evolution and localized tendencies of SSS during severe shear deformation. Our results demonstrate the dislocation mediated microstructural refinement process in each phase of the binary alloy and the mechanisms associated with localized solute supersaturation as a function of shear strain. Pronounced grain refinement in the softer Cu phase occurs owing to the strain localization driving the preferential dynamic recrystallization. The grain refinement of the Cr phase, however, is enabled by the progressive evolution of grain lamination, splitting, and fragmentation as a function of shear strain. The solute supersaturation is found to be strongly dependent on the local environments that affect the dislocation activity, including the level of microstructure refinement, the interfacial orientation relationship, the mechanical incompatibility, and the localized preferential phase oxidation. Ab initio simulations confirm that it is more favorable to oxidize Cr than Cu at incoherent Cu/Cr interfaces, limiting the mass transport on an incoherent boundary. Our results unveil the mechanism underpinning the non-equilibrium mass transport in immiscible systems upon severe deformation that can be applied to produce immiscible alloys with superior mechanical properties.

强制混合成单相或过饱和固溶体（SSS）及其在不混溶系统中的先决微观结构演化一直是基础科学和实际应用研究的重点。通过剪切变形控制 SSS 的形成可以使材料设计超越不混溶系统中的传统平衡微观结构。在这里，高度不混溶的 Cu-50 at.% Cr 二元合金（混合焓约为 20 kJ mol ^-1) 用于研究 SSS 在严重剪切变形过程中的微观结构演变和局部趋势。我们的研究结果证明了二元合金每一相中位错介导的微观结构细化过程以及与局部溶质过饱和相关的机制作为剪切应变的函数。由于应变局部化驱动优先动态再结晶，在较软的 Cu 相中出现明显的晶粒细化。然而，Cr 相的晶粒细化是通过晶粒分层、分裂和破碎作为剪切应变的函数的逐步演变来实现的。发现溶质过饱和强烈依赖于影响位错活动的局部环境，包括微观结构细化水平，界面取向关系，机械不相容性和局部优先相氧化。从头算模拟证实，在非共格 Cu/Cr 界面氧化 Cr 比氧化 Cu 更有利，从而限制了非共格边界上的质量传输。我们的研究结果揭示了在严重变形时支持不混溶系统中非平衡质量传输的机制，可用于生产具有优异机械性能的不混溶合金。