Hardening behaviour of partially crystallised amorphous Al alloys

A mixture model in which a partially crystallised amorphous Al alloy is regarded as a nanocomposite of a Al nanoparticle and a remaining amorphous matrix is presented. The model aims at describing the hardening behaviour of primary heat treated amorphous Al–Ni–Y alloys, in which the strength (and hardness) changes according to the composition and microstructure from approximately 1000 MPa for the as-melt spun amorphous ribbon to 1500 MPa after heat treatment. The nano-sized Al particles are treated as perfect materials because there are hardly any imperfections within the particles. The matrix is treated as amorphous materials, in which the solute concentration increases with the volume fraction of Al particles. The calculated results for various compositions and heat treated specimens are compared with experimental data in literature. It is shown that the hardness of the nanocomposite is independent of the solute concentration profile only if the hardness of the amorphous matrix is proportional to the solute concentration.