The Ni-Co-V medium-entropy alloy exhibits exceptional strength and ductility, often attributed to its pronounced chemical short-range order (CSRO) driven by Ni-V and Co-V affinity. Yet how this tunable CSRO governs stacking-fault energetics and dislocation motion remains unresolved. Using atomistic simulations based on our first-principles-trained interatomic potential, we show that as CSRO intensifies, the average intrinsic stacking-fault energy increases from 25 to $95\text{mJ}{\text{m}}^{-2}$ and the mean critical resolved shear stress rises from $340.9\pm 23.0$ to $521.3\pm 20.9\text{MPa}$. Dislocation analysis reveals reduced partial separation and enhanced resistance to partial-dislocation glide with increasing order. Introducing Ni-V- and Co-V-rich CSRO clusters along the glide plane induces bowing, kinking, and transient pinning, demonstrating spatially heterogeneous chemical strengthening. These results quantitatively link CSRO to stacking-fault-mediated plasticity and establish tunable strength-ductility through controlled local chemical order in Ni-Co-V systems.

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• Defects
• Interatomic & molecular potentials
• Stacking faults
• Alloys
• Materials modeling
• Molecular dynamics