Tension-compression strength asymmetry of nanocrystalline α-Fe2O3+fcc-Al ceramic-metal composites.

The dependence on composition and loading direction of the strength of nanocrystalline α-Fe2O3+fcc-Al composites is analyzed using molecular dynamics simulations with a recently developed multicomponent interatomic potential. Compressive strength values are found to be higher than the tensile strength values at all volume fractions of the phases. Reverse Hall-Petch relations are observed for tension and forward Hall-Petch relations are observed for compression. The observed asymmetry in behavior and the direct or reverse nature of the Hall-Petch relations are found to reflect the different manners in which pairwise electrostatic forces influence grain boundary sliding which is the primary deformation mechanism. [ABSTRACT FROM AUTHOR]