TY - JOUR

T1 - Resolving the fundamentals of the J-integral concept by multi-method in situ nanoscale stress-strain mapping

AU - Meindlhumer, Michael

AU - Alfreider, Markus

AU - Sheshi, Noel

AU - Hohenwarter, Anton

AU - Todt, Juraj

AU - Rosenthal, Martin

AU - Burghammer, Manfred

AU - Salvati, Enrico

AU - Keckes, Jozef

AU - Kiener, Daniel

PY - 2025/2/22

Y1 - 2025/2/22

N2 - The integrity of structural materials is oftentimes defined by their resistance against catastrophic failure through dissipative plastic processes at the crack tip, commonly quantified by the J-integral concept. However, to date the experimental stress and strain fields necessary to quantify the J-integral associated with local crack propagation in its original integral form were inaccessible. Here, we present a multi-method nanoscale strain- and stress-mapping surrounding a growing crack tip in two identical miniaturized fracture specimens made from a nanocrystalline FeCrMnNiCo high-entropy alloy. The respective samples were tested in situ in a scanning electron microscope and a synchrotron X-ray nanodiffraction setup, with detailed analyzes of loading states during elastic loading, crack tip blunting and general yielding, corroborated by a detailed elastic-plastic finite element model. This complementary in situ methodology uniquely enabled a detailed quantification of the J-integral along different integration paths from experimental nanoscale stress and strain fields. We find that conventional linear-elastic and elastic-plastic models, typically used to interpret fracture phenomena, have limited applicability at micron to nanoscale distances from propagating cracks. This for the first time unravels a limit to the path-independence of the J-integral, which has significant implications in the development and assessment of modern damage-tolerant materials and microstructures.

AB - The integrity of structural materials is oftentimes defined by their resistance against catastrophic failure through dissipative plastic processes at the crack tip, commonly quantified by the J-integral concept. However, to date the experimental stress and strain fields necessary to quantify the J-integral associated with local crack propagation in its original integral form were inaccessible. Here, we present a multi-method nanoscale strain- and stress-mapping surrounding a growing crack tip in two identical miniaturized fracture specimens made from a nanocrystalline FeCrMnNiCo high-entropy alloy. The respective samples were tested in situ in a scanning electron microscope and a synchrotron X-ray nanodiffraction setup, with detailed analyzes of loading states during elastic loading, crack tip blunting and general yielding, corroborated by a detailed elastic-plastic finite element model. This complementary in situ methodology uniquely enabled a detailed quantification of the J-integral along different integration paths from experimental nanoscale stress and strain fields. We find that conventional linear-elastic and elastic-plastic models, typically used to interpret fracture phenomena, have limited applicability at micron to nanoscale distances from propagating cracks. This for the first time unravels a limit to the path-independence of the J-integral, which has significant implications in the development and assessment of modern damage-tolerant materials and microstructures.

UR - https://doi.org/10.1038/s43246-025-00752-z

M3 - Article

VL - 2025

JO - Communications materials

JF - Communications materials

SN - 2662-4443

IS - 6

M1 - 35

ER -