Abstract
Nanoprecipitate-strengthened medium/high entropy alloys (M/HEAs) with ultrahigh strengths and unusual physical properties represent promising candidates for structural applications. However, further strengthening these materials usually relies on increasing the volume fraction of nanoprecipitates and/or introducing harder intermetallics that inevitably sacrifice the ductility. Here, we report a strategy to break this trade-off in a Co-Cr-Ni-based MEA by architecting a hierarchical heterostructure that integrates high-volume fraction (up to ∼30%) D022-γ’’ nanoprecipitates, shearable and non-shearable intermetallic particles, with a low stacking fault energy (SFE) matrix with heterogeneous grain structure. This hierarchical heterostructure can arouse hybrid strengthening mechanisms and lead to cross-scale and dynamic strain partitioning during plastic deformation, contributing to a superior strain-hardening capability and an excellent combination of the yield / ultimate tensile strength of 1323 MPa / 1690 MPa and 29% tensile elongation. This study provides a promising paradigm to design ultrastrong and ductile metallic materials via controlling multiscale microstructural heterogeneities.
Original language | English |
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Article number | 119492 |
Journal | Acta Materialia |
Volume | 263 |
DOIs | |
Publication status | Published - 15 Jan 2024 |
Keywords
- Hetero-deformation-induced strengthening
- Hierarchical microstructure
- Mechanical properties
- Medium-entropy alloy
- Precipitation strengthening