Mechanical properties of crystalline-amorphous composites: Generalization of Hall-Petch and inverse Hall-Petch behaviors

Abstract

The strength, of a polycrystal decreases with the mean grain diameter for atoms (i.e. Hall-Petch behavior) and increases for (i.e. inverse Hall-Petch behavior). Our simulations generalize to, where is the mean thickness of amorphous grain boundaries of crystalline-amorphous composites. The maximum strength is reached at atoms for single-component face-centered-cubic solids and at for bidispersed or body-centered-cubic solids because of the different activation stresses of dislocation motions. The results explain recent alloy experiments and provide a way to exceed the maximum strength of polycrystals. Ductility and elastic moduli are also measured in the broad space. In regimes without a strength-ductility trade-off, the maximum ductility and ductile-brittle transitions are identified. These results obtained in space are important in solid mechanics and can guide the fabrication of crystalline-amorphous composites with outstanding mechanical properties.