Interfaces have been reported to significantly strengthen and toughen metallic materials. However, there has been a long-standing question on whether interface-affected-zone (IAZ) exists, and how it might behave. Here we report in situ high-resolution strain mapping near interfaces in a copper–bronze heterogeneous laminate, which revealed the existence of IAZs. Defined as the zone with strain gradient, the IAZ was found to form by the dislocations emitted from the interface. The IAZ width remained largely constant with a magnitude of a few micrometers with increasing applied strain. Interfaces produced both back stress strengthening and work hardening, which led to both higher strength and higher ductility with decreasing interface spacing until adjacent IAZs started to overlap, after which a tradeoff between strength and ductility occurred, indicating the existence of an optimum interface spacing for the best mechanical properties. These findings are expected to help with designing laminates and other heterogeneous metals and alloys for superior mechanical properties.

中文翻译：

---

异质层压板中最佳强度和延展性的界面影响区

据报道，界面可以显着增强和增韧金属材料。然而，关于接口影响区 (IAZ) 是否存在以及它可能如何表现，一直存在一个长期存在的问题。在这里，我们报告了铜-青铜异质层压板中界面附近的原位高分辨率应变映射，这揭示了 IAZ 的存在。定义为具有应变梯度的区域，发现 IAZ 是由从界面发射的位错形成的。随着外加应变的增加，IAZ 宽度基本保持恒定，幅度为几微米。界面产生背应力强化和加工硬化，这导致更高的强度和更高的延展性，随着界面间距的减小，直到相邻的 IAZ 开始重叠，之后发生强度和延展性之间的权衡，表明存在最佳机械性能的最佳界面间距。预计这些发现将有助于设计具有优异机械性能的层压板和其他异质金属和合金。