Residual stress exists extensively in biological and engineering structures. Here we report that residual stress can be engineered to significantly enhance the strength and ductility of gradient materials. In-situ synchrotron experiments revealed that the strongest strain hardening occurred in the layer with the highest compressive residual stress in a gradient structure. This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility. This finding provides a new paradigm for designing gradient structures for superior mechanical properties.

残余应力广泛存在于生物和工程结构中。在这里，我们报告可以设计残余应力以显着增强梯度材料的强度和延展性。原位同步加速器实验表明，最强的应变硬化发生在梯度结构中具有最高压缩残余应力的层中。在拉伸过程中，该层比相邻层保持弹性的时间更长，即使在压缩应力消失后，也能产生较高的异质形变诱导应力，从而提高强度并增强加工硬化，从而提高延展性。这一发现为设计具有优异机械性能的梯度结构提供了新的范例。