Solvent-enriched interface enables ductility in an ultrastrong alloy
Yunzhu Shi (Hunan University)
Liuliu Han (Max Planck Institute for Sustainable Materials)
Fei Zhang (Chinese Academy of Sciences)
Wei Chen (AVIC Manufacturing Technology Institute)
Alexander Schökel (Deutsches Elektronen-Synchrotron DESY)
Yan Ma (TU Delft - Team Maria Santofimia Navarro)
Claudio Pistidda (Helmholtz-Zentrum Hereon)
Zhifeng Lei (Hunan University)
Zhaoping Lu (University of Science and Technology Beijing)
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Abstract
In metals and alloys, solute segregation at grain boundaries typically undermines cohesion and ductility. Here, we overturn this paradigm by showing that solvent Fe atoms can preferentially enrich low-angle grain boundaries (LAGBs) in a ferrous alloy, dramatically enhancing ductility. Cold rolling and aging generate coherent nanoprecipitates, a high dislocation density, and abundant LAGBs in an austenitic matrix, yielding an ultrahigh tensile yield strength of ∼ 1.74 GPa. Moreover, the solvent Fe enrichment at LAGBs lowers local stacking fault energy and activates austenite-to-martensite transformation under load. This transformation-induced plasticity effect stabilizes plastic flow, enabling a uniform elongation of ∼ 26.2 % despite the alloy’s exceptional strength. Our findings challenge conventional views of segregation and offer a new design strategy for ultra-strong, highly ductile alloys.
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File under embargo until 15-06-2026