Metals can be processed to reach ultra-high strength, but usually at a drastic loss of ductility. Here, we review recent advances in overcoming this tradeoff, by purposely deploying heterogeneous nanostructures in an otherwise single-phase metal. Several structural designs are being explored, including bimodal, harmonic, lamellar, gradient, domain-dispersed, and hierarchical nanostructures. These seemingly distinct tactics share a unifying design principle in that the intentional structural heterogeneities induce non-homogeneous plastic deformation, and the nanometer-scale features dictate steep strain gradients, thereby enhancing strain hardening and consequently uniform tensile ductility at high flow stresses. Moreover, these heterogeneous nanostructures in metals play a role similar to multiple phases in complex alloys, functionally graded materials and composites, sharing common material design and mechanics principles. Our review advocates this broad vision to help guide future innovations towards a synergy between high strength and high ductility, through highlighting several recent designs as well as identifying outstanding challenges and opportunities.

中文翻译：

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通过设计金属中的异质纳米结构实现强度-延展性协同作用

金属可以进行加工以达到超高强度，但通常会严重损失延展性。在这里，我们通过有目的地在单相金属中部署异质纳米结构，回顾了克服这种权衡的最新进展。正在探索几种结构设计，包括双峰、谐波、层状、梯度、域分散和分层纳米结构。这些看似不同的策略共享一个统一的设计原则，即有意的结构异质性导致非均匀塑性变形，纳米级特征决定了陡峭的应变梯度，从而增强了应变硬化，从而在高流动应力下提高了均匀的拉伸延展性。此外，金属中的这些异质纳米结构的作用类似于复杂合金中的多相，功能梯度材料和复合材料，共享共同的材料设计和力学原理。我们的评论提倡这一广阔的愿景，通过突出几个最近的设计以及确定突出的挑战和机遇，帮助指导未来的创新实现高强度和高延展性之间的协同作用。