STRENGTHENING OF ALUMINIUM BY A 3-DIMENSIONAL NETWORK OF ALUMINIUM-OXIDE PARTICLES

Aluminium products containing a three-dimensional network of closely spaced oxide particles have been studied by transmission electron microscopy and tensile testing at room temperature and 400°C. A network of hard particles was found to strengthen aluminium effectively, almost as much as a uniform dispersion of particles. It is shown that the relationship between the tensile stress (0.01% and 0.2% offset) and the mesh size tm of the oxide network in a plane can be expressed by the equation σ = σ0 + k · tm -1 2 where k is a constant independant of the mesh size. A theoretical expression for k is derived on the assumption that dislocations pile up at the oxide boundaries and that they pass the boundaries by an Orowan mechanism, and agreement is ssen to exist between calculations and experiments. In accordance with theory it is shown that k varies with temperature as does the elastic modulus. © 1969.