Uniform tensile ductility (UTD) is crucial for the forming/machining capabilities of structural materials. Normally, planar-slip induced narrow deformation bands localize the plastic strains and hence hamper UTD, particularly in body-centred-cubic (bcc) multi-principal element high-entropy alloys (HEAs), which generally exhibit early necking (UTD < 5%). Here we demonstrate a strategy to tailor the planar-slip bands in a Ti-Zr-V-Nb-Al bcc HEA, achieving a 25% UTD together with nearly 50% elongation-to-failure (approaching a ductile elemental metal), while offering gigapascal yield strength. The HEA composition is designed not only to enhance the B2-like local chemical order (LCO), seeding sites to disperse planar slip, but also to generate excess lattice distortion upon deformation-induced LCO destruction, which promotes elastic strains and dislocation debris to cause dynamic hardening. This encourages second-generation planar-slip bands to branch out from first-generation bands, effectively spreading the plastic flow to permeate the sample volume. Moreover, the profuse bands frequently intersect to sustain adequate work-hardening rate (WHR) to large strains. Our strategy showcases the tuning of plastic flow dynamics that turns an otherwise-undesirable deformation mode to our advantage, enabling an unusual synergy of yield strength and UTD for bcc HEAs.

均匀拉伸延展性 (UTD) 对于结构材料的成型/加工能力至关重要。通常，平面滑移引起的窄变形带会使塑性应变局域化，从而阻碍 UTD，特别是在体心立方 (bcc) 多主元高熵合金 (HEA) 中，通常表现出早期颈缩 (UTD < 5%) ）。在这里，我们展示了一种在 Ti-Zr-V-Nb-Al bcc HEA 中定制平面滑移带的策略，实现了 25% UTD 以及近 50% 的断裂伸长率（接近延展性元素金属），同时提供千兆帕的屈服强度。HEA 成分的设计不仅可以增强类 B2 局部化学有序 (LCO)、晶种位点以分散平面滑移，而且还可以在变形引起的 LCO 破坏时产生过度的晶格畸变，从而促进弹性应变和位错碎片，从而导致动态硬化。这促使第二代平面滑移带从第一代带中分支出来，有效地传播塑料流以渗透样品体积。此外，丰富的带经常相交，以维持足够的加工硬化率（WHR）以应对大应变。我们的策略展示了塑性流动动力学的调整，将原本不需要的变形模式转变为我们的优势，从而使 bcc HEA 的屈服强度和 UTD 产生不寻常的协同作用。