Correlative microscopy across three dimensions bridges millimetre and atomic scales to analyze crack matrix interfaces

A correlative workflow is developed for analyzing subsurface crack tips located hundreds of micrometers deep in metallic samples, enabling precise characterization of specific regions of interest by integrating multi-scale data across various microscopy techniques. Using X-ray computed tomography mapping, a crack is selected from a group of candidate cracks and extracted with Laser focused ion beam. The isolated crack is examined using three-dimensional electron backscatter diffraction, revealing that the crack propagated along prior austenite grain boundaries. In addition, the martensitic microstructure exhibits crack deflection and crack-tip blunting at block boundaries and prior austenite grain boundaries triple junction. Additionally, crack propagation is found to be influenced by grain boundary structure and elemental segregation. The nucleation and formation of zinc-rich intermetallic phases along the grain boundaries can weaken grain boundaries and lead to crack propagation. Such insights, linking structure and chemistry across multiple length scales, are possible through this integrated multiscale workflow. A correlative workflow is developed for analyzing subsurface crack tips located hundreds of micrometers deep in metallic samples, enabling precise characterization of specific regions of interest by integrating multi-scale data across various microscopy techniques.