INVESTIGATION OF THE FABRICATION OF BN-REINFORCED PURE ALUMINUM COMPOSITES BY CASTING PROCESSE

Purpose. The main objective of this research was to evaluate the feasibility of producing aluminum matrix composites (AMC) based on pure aluminum reinforced with boron nitride using casting technologies, in particular the stir casting method. This approach was chosen due to its technological simplicity, relatively low cost, and potential scalability for industrial applications. Research methods. To analyze the distribution and morphology of the reinforcing particles, microstructural metallographic analysis using optical microscopy was applied. The chemical composition of the composites was determined by X-ray fluorescence analysis and spark optical emission spectrometry. These methods provided reliable data on the content and incorporation of boron nitride particles into the aluminum matrix, as well as the influence of additional alloying elements (Ni, Sn, Zr) on the composite structure. Results. Experimental AMC samples containing 1–3 wt.% BN were produced by stir casting, including variants with fluxes and alloying elements under different melting conditions. The composite structures contained BN particles evenly distributed in the matrix; however, their actual content was only 7–15 % of the amount initially introduced in the charge. It was found that the efficiency of BN incorporation strongly depends on the melt composition (amount of reinforcing particles, presence of fluxes and microalloying elements) and on the melting parameters (superheating temperature, stirring time). The porosity of the obtained composites was also studied: the addition of BN significantly increased porosity, whereas the presence of Sn reduced it due to eutectic formation. Scientific novelty. New data were obtained on the feasibility of producing AMCs based on pure aluminum with BN reinforcement by stir casting with the use of fluxes and microalloying additives, which improve BN incorporation. Practical value. The results complement existing knowledge on AMC fabrication and explain the lack of studies using pure aluminum as the matrix. The findings may also be applied to optimize casting technologies for manufacturing aluminum matrix composites.