Materials with heterogeneous microstructures have been reported to have an attractive combination of strength and ductility. This is attributed to synergistic strengthening effects from the difference in strength of fine- and coarse-grained regions. Understanding the interaction of the regions is crucial for further optimization of the microstructures. In this work, we fabricated nickel of harmonic structure (HS) and a reference with homogenous coarse grains. The HS constitutes of an interconnected fine-grained network that surrounds regions of coarse grains. The interplay of the regions was studied by monitoring Bragg reflections from individual grains in situ during tensile deformation until approximately 2 % strain through synchrotron X-ray diffraction. The technique allows grain-level assessment of the degree of plastic deformation. Two grains were followed in the reference and two small grains (fine-grained region) and two large grains (coarse-grained region) in the HS. Three deformation regimes were identified: elastic deformation, onset of plastic deformation and significant plastic deformation. Our results reveal that the large grains in the harmonic structure onset plastic deformation during the macroscopic elastic stage. With increasing applied stress, the small grains yield plastically also and once a large fraction of the fine-grained network deforms plastically the large grains undergo significant plastic deformation. Notably, the onset of significant plastic deformation of large grains in the HS occurs at approximately 100 MPa higher applied stress than in the grains in the reference. This shows that fine grains constrain the large grains from deforming plastically in the HS.

据报道，具有异质微观结构的材料具有有吸引力的强度和延展性组合。这是由于细晶粒和粗晶粒区域的强度差异产生的协同强化效应。了解区域的相互作用对于进一步优化微观结构至关重要。在这项工作中，我们制造了谐波结构（HS）镍和具有均匀粗晶粒的参考。HS 由围绕粗粒区域的互连细粒网络组成。通过同步加速器 X 射线衍射监测拉伸变形直至约 2% 应变期间原位单个晶粒的布拉格反射，研究了这些区域的相互作用。该技术可以对塑性变形程度进行晶粒级评估。参考中跟随两个晶粒，HS 中跟随两个小晶粒（细粒区域）和两个大晶粒（粗粒区域）。确定了三种变形方式：弹性变形、塑性变形开始和显着塑性变形。我们的结果表明，调和结构中的大晶粒在宏观弹性阶段开始塑性变形。随着施加应力的增加，小晶粒也会塑性屈服，一旦细晶粒网络的大部分发生塑性变形，大晶粒就会经历显着的塑性变形。值得注意的是，HS 中大晶粒的显着塑性变形发生在比参考晶粒高约 100 MPa 的施加应力下。这表明细晶粒限制大晶粒在 HS 中发生塑性变形。