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Updated: Mar 6, 2026

Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
Bone-like crack resistance in hierarchical metastable nanolaminate steels
Motomichi Koyama1, Zhao Zhang2, Meimei Wang3,4
1Kyushu University, Motooka 744, 819-0395 Fukuoka, Japan. koyama@mech.kyushu-u.ac.jp mm_wang@mit.edu tasan@mit.edu.
Abstract:
Fatigue failures create enormous risks for all engineered structures, as well as for human lives, motivating large safety factors in design and, thus, inefficient use of resources. Inspired by the excellent fracture toughness of bone, we explored the fatigue resistance in metastability-assisted multiphase steels. We show here that when steel microstructures are hierarchical and laminated, similar to the substructure of bone, superior crack resistance can be realized. Our results reveal that tuning the interface structure, distribution, and phase stability to simultaneously activate multiple micromechanisms that resist crack propagation is key for the observed leap in mechanical response. The exceptional properties enabled by this strategy provide guidance for all fatigue-resistant alloy design efforts.
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