Advanced Materials, 2026; 0:e21409

Keywords: Plastic deformation, Microstructure, Micromechanics modeling, Nickel-based superalloys, Heterogeneous Materials

The hetero-deformation mechanisms were systematically investigated using in-situ SEM and EBSD, combined with crystal plasticity finite element (CPFE) modeling. The results reveal that the softer single-crystal domain yields first due to the lower slip strength, accompanying by the lattice rotation and geometrically necessary dislocation (GND) accumulation near the single/polycrystal hetero-boundary (HB), which induces pronounced local hardening, thereby driving the sites of plastic strain accumulation shifting from HB to the interior of the single-crystal domain during the following cyclic loading. This GND density field is primarily controlled by the Delta Exx (the difference of the elastic modulus along the loading direction), the minimum crystallographic misorientation (theta') between the <001> of the polycrystalline grain and the loading direction (nearly parallel to [010] of single-crystal grain), and the intrinsic slip strength on the both sides of HB. Low <001> misorientation (theta ' <= 15 degrees) or small Delta E-xx (<= 30 GPa), in combination with high geometric compatibility factor (m ' >= 0.8) decrease the demand for GND-associated compatibility near the HB. These results provide mechanistic insights for designing interfaces that enhance fatigue resistance and damage tolerance in the single/polycrystal nickel-based superalloys.

Xinrui Xiao, Liwu Liu , Xiaoxian Zhang , Yanju Liu , Jinsong Leng

Hetero-deformation mechanisms and GND-associated plastic strain partitioning across single polycrystal hetero-boundary in nickel-based superalloys.pdf