In situ fibre-reinforced composites were prepared by very heavy straining that elongates the minor phase into very fine ribbons, producing materials of extremely high strength. Strengthening was usually explained by the many geometrically necessary dislocations or by pile-ups produced at the many interfaces. It was shown here by transmission electron microscopy that nanoscale ribbons became dislocation-free and the matrix too fine to accommodate dislocation substructures. A modified strengthening model was proposed based on ribbons having the ideal strength in the substructure-free matrix.

New Model for Strengthening by Dislocation Nucleation in Nanoscale in situ Composite Microwires. D.G.Morris, M.A.Muñoz-Morris: Scripta Materialia, 2008, 59[8], 838-41