As one of the heterostructures, the layered structure has attracted extensive research interest as it achieves superior properties to individual components. The layer interface is considered a critical factor in determining the mechanical properties of layered metals, where heterogeneity across the interface results in the strengthening of the soft layer and forming an interfacial stress gradient in the hard layer. However, there is still limited research associated with the formation of interfacial stress gradients in the hard layer, as stress measurement at high spatial resolution remains technically challenging. In the present study, we experimentally quantified the formation of interfacial stress gradients in the Ti layer of Ti/Al layered metal upon tension using in-situ high-energy X-ray diffraction (XRD). The analysis coupling in-situ high-energy XRD and in-situ electron back-scattered diffraction (EBSD) suggested that the interfacial stress gradient in the Ti layer rapidly rose as the Al layer was insufficient to accommodate the deformation of Ti. During the later deformation stage, collective effects of dislocation motion and geometrically necessary dislocation (GND) accumulation in the Al layer determined the evolution of interfacial stress gradients. The maximum interfacial stress gradient is below 0.4 MPa/μm in Ti layers, with a constant range width of 35 μm independent of the macroscopic strain. The present study therefore opens a new window to local stress modification using incompatible component deformation, which is instructive for the design and fabrication of high-performance layered metals.

中文翻译：

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原位同步加速器高能X射线衍射与原位EBSD耦合研究层状金属界面应力梯度

作为异质结构之一，层状结构因其具有优于单个组件的性能而引起了广泛的研究兴趣。层界面被认为是决定层状金属机械性能的关键因素，界面上的异质性导致软层强化并在硬层中形成界面应力梯度。然而，与硬层中界面应力梯度形成相关的研究仍然有限，因为高空间分辨率下的应力测量在技术上仍然具有挑战性。在本研究中，我们使用原位高能 X 射线衍射 (XRD) 实验量化了 Ti/Al 层状金属的 Ti 层在拉伸时界面应力梯度的形成。原位高能 XRD 和原位电子背散射衍射 (EBSD) 相结合的分析表明，由于 Al 层不足以容纳 Ti 的变形，Ti 层中的界面应力梯度迅速上升。在变形后期，Al层中位错运动和几何必要位错（GND）积累的集体效应决定了界面应力梯度的演变。 Ti 层中的最大界面应力梯度低于 0.4 MPa/μm，恒定范围宽度为 35 μm，与宏观应变无关。因此，本研究为利用不相容部件变形进行局部应力修改打开了一个新窗口，这对于高性能层状金属的设计和制造具有指导意义。