Intergranular fracture plays an important role in polycrystalline materials including high entropy alloys, but the atomic scale fracture mechanisms of individual grain boundaries (GBs) are still not fully understood. In this work, we selectively investigate the fracture behaviors of individual GBs in a single-phase face-centered cubic CoCrFeNi high entropy alloy via in situ transmission electron microscopy (TEM) nanomechanical testing supported by molecular dynamics (MD) simulations. With this set up, the classic mode I crack propagation along GBs can be dynamically visualized and quantitatively analyzed.
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