Introduction of reinforcing microparticles of TiB2 and BN into aluminium by electromagnetic stirring

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The paper describes an experiment in which aluminum alloy was reinforced with TiB2 and BN particles and investigates the physical properties of the resulting aluminum composite. In the experiment, TiB2 and BN reinforcing particles were introduced into molten metal as part of pellets produced from aluminum micro powder in the presence of MHD mixing with subsequent directional crystallization. The pellets were thrown into a crucible with liquid aluminum placed in the working volume of an MHD stirrer, which generated separately controlled toroidal and poloidal flows. It was found that the dissolution of the pellets prepared from the mixture of aluminum micro particles (100–150 μm) and reinforcing TiB2 micro particles (1–5 μm) under MHD stirring proceeds much better compared to the pellets with BN micro particles (1–5 μm). The pellets in which the weight percentage of BN reinforcing particles exceeds 7% poorly “dissolve” in aluminum melt, while the pellets with 10% TiB2 micro particles “dissolve” satisfactorily. Due to a large number of pellets introduced into liquid aluminum in the course of the experiment and because of the strong cooling of the melt, it was not possible to obtain the weight percentage of reinforcing micro particles in an aluminum ingot exceeding 2.5% for TiB2 micro particles and 1.4% for BN micro particles. The results of the experiment showed that the hardness and tensile strength of aluminum increase with increasing content of TiB2 and BN micro particles in a similar way, but in the case BN particles to a lesser extent. The strength and electrical resistivity of liquid aluminum reinforced with TiB2 and BN particles increase with their rising fraction.The structural study of the specimens on electron and digital optical microscopes were carried out in compliance with the state budget subject AAAAA19-119012290101-5 of the Institute of Continuum Mechanics at the UralBranch of the Russian Academy of Sciences; the experiments on introduction of microparticles into molten aluminium were funded by the Government of the Perm Kray and the Russian Foundation for Basic Research under the Ural regional project No. [19-48-590001 р_а].