The evolution of strain hardening behavior of the Fe₅₀(CoCrMnNi)₅₀ medium-entropy alloy as a function of the fraction of recrystallized microstructure and the grain size was studied using the Hollomon and Ludwigson equations. The specimens under study were partially recrystallized, fully recrystallized with ultrafine-grained microstructure, and fully recrystallized with coarse grains. The yield strength decreases steadily as the fraction of recrystallized microstructure and grain size increases due to the recovery process and the Hall–Petch effect. Interestingly, the bimodal grain distribution was found to have a significant impact on strain hardening during plastic deformation. For instance, the highest ultimate tensile strength was exhibited by a 0.97 μm specimen, which was observed to contain a bimodal grain distribution. Furthermore, using the Ludwigson equation, the effect of the bimodal grain distribution was established from the behavior of K₂ and n₁ curves. These curves tend to show very high values in the specimens with a bimodal grain distribution compared to those that show a homogenous grain distribution. Additionally, the bimodal grain distribution contributes to the extensive Lüders strain observed in the 0.97 μm specimen, which induces a significant deviation of the Hollomon equation at lower strains.

Fe ₅₀（CoCrMnNi）₅₀的应变硬化行为演变使用Hollomon和Ludwigson方程研究了中熵合金作为再结晶组织分数和晶粒尺寸的函数。所研究的样品进行了部分重结晶，具有超细晶粒组织的完全重结晶以及具有粗晶粒的完全重结晶。屈服强度随着再结晶组织的分数和晶粒尺寸的增加而稳步下降，这归因于恢复过程和霍尔—帕奇效应。有趣的是，发现双峰晶粒分布对塑性变形过程中的应变硬化有重大影响。例如，0.97μm的样品表现出最高的极限抗拉强度，该样品具有双峰晶粒分布。此外，使用Ludwigson方程，K ₂和n ₁曲线。与具有均匀晶粒分布的曲线相比，这些曲线在具有双峰晶粒分布的样品中往往显示出非常高的值。此外，双峰晶粒分布有助于在0.97μm样品中观察到广泛的Lüders应变，这会导致在较低应变下Hollomon方程的显着偏离。