In-situ X-ray tomographic imaging and controlled steering of microcracks in 3D nanopatterned structures

•A novel technique to monitor and control the microcracking process in specially designed 3D nanopatterned structures in real time is demonstrated on a technically relevant materials system, i.e. an on-chip interconnect stack. The three-dimensional details of the complicated physical failure mechanism are unveiled with high resolution.•The combination of X-ray microscopy and micromechanics and the ability to image microcracks in a model system with a hierarchically structured architecture is described.•The critical energy release rate at the crack tip is determined quantitatively in sub-100 nm regions.•A controlled microcrack steering into regions with high fracture toughness is demonstrated for an engineered hierarchical materials system.