The strength–ductility trade-off has long been a Gordian knot in conventional metallic structural materials and it is no exception in multi-principal element alloys. In particular, at ultrahigh yield strengths, plastic instability, that is, necking, happens prematurely, because of which ductility almost entirely disappears. This is due to the growing difficulty in the production and accumulation of dislocations from the very beginning of tensile deformation that renders the conventional dislocation hardening insufficient. Here we propose that premature necking can be harnessed for work hardening in a VCoNi multi-principal element alloy. Lüders banding as an initial tensile response induces the ongoing localized necking at the band front to produce both triaxial stress and strain gradient, which enables the rapid multiplication of dislocations. This leads to forest dislocation hardening, plus extra work hardening due to the interaction of dislocations with the local-chemical-order regions. The dual work hardening combines to restrain and stabilize the premature necking in reverse as well as to facilitate uniform deformation. Consequently, a superior strength-and-ductility synergy is achieved with a ductility of ~20% and yield strength of 2 GPa during room-temperature and cryogenic deformation. These findings offer an instability-control paradigm for synergistic work hardening to conquer the strength–ductility paradox at ultrahigh yield strengths.

强度与延展性的权衡长期以来一直是传统金属结构材料中的一个难题，对于多主元合金也不例外。特别是，在超高屈服强度下，塑性不稳定性（即颈缩）会过早发生，因此延展性几乎完全消失。这是由于从拉伸变形一开始位错的产生和积累就变得越来越困难，这使得传统的位错硬化变得不够。在这里，我们建议可以利用过早颈缩来实现 VCoNi 多主元素合金的加工硬化。吕德斯带作为初始拉伸响应会引起带前部持续的局部颈缩，从而产生三轴应力和应变梯度，从而实现位错的快速倍增。这导致森林位错硬化，加上由于位错与局部化学有序区域的相互作用而导致额外的加工硬化。双重加工硬化结合起来可以抑制和稳定反向过早颈缩，并促进均匀变形。因此，在室温和低温变形过程中，实现了卓越的强度和延展性协同作用，延展性约为 20%，屈服强度为 2 GPa。这些发现为协同加工硬化提供了一种不稳定性控制范例，以克服超高屈服强度下的强度-延展性悖论。