Addition alloys (master alloys) and flux additives are widely used to solve the problems of changing of the structure (reduction of a grain size, change in eutectic size and shape, etc.) and, as a consequence, physical and mechanical properties of the cast material.
Fluxes (preparations) containing micro-additives are the mixture of salts with certain composition passed through thermal homogenization and containing fine particles, for example, TiB2, whose size is approximately one micrometer.
The developed compositions can also contain pure elements: Cu, Ti, Fe, B, P, Zr, etc. as fine particles.
These flux preparations, as well as addition alloys (master alloys) with different chemical composition, are developed and produced “to order”.
This is one example of the application of flux preparations. For a casting hypereutectic aluminium alloy with 30%-silicon and 5%-nickel content, a flux preparation containing P and TiB2 additives is proposed. After processing of the melt, we managed to obtain the following properties of cast material: the coefficient of linear thermal expansion – 14·10-6 1/°С, tensile strength – 20 kg/мм2, plasticity-elongation – 2%.
