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Updated: May 12, 2026

Full-field Strain Measurements for Microstructurally Small Fatigue Crack Propagation Using Digital Image Correlation Method
Published on: January 16, 2019
Uncommon deformation mechanisms during fatigue-crack propagation in nanocrystalline alloys
Sheng Cheng1, Soo Yeol Lee, Li Li
1Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA. scheng.msg@gmail.com
Abstract:
The irreversible damage at cracks during the fatigue of crystalline solids is well known. Here we report on in situ high-energy x-ray evidence of reversible fatigue behavior in a nanocrystalline NiFe alloy both in the plastic zone and around the crack tip. In the plastic zone, the deformation is fully recoverable as the crack propagates, and the plastic deformation invokes reversible interactions of dislocation and twinning in the nanograins. But around the crack tip lies a regime with reversible grain lattice reorientation promoted by a change of local stress state. These observations suggest unprecedented fatigue deformation mechanisms in nanostructured systems that are not addressed theoretically.
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