[en] Full text: For many years metal matrix composites (MMC) continue to attract interest in both scientific and industrial fields. The combined effect of a ductile metallic matrix and a strong reinforcing phase allows for achievement of properties unreachable for traditional alloys. In our previous works we showed that utilization of BN nano- and microparticles as reinforcing phase in Al-based composite materials resulted in significant increase of material strength. In work powder mixtures were obtained using ball milling technique, which led to formation of additional phases on the Al – BN interphase: AlB2 and AlN. The aim of the present work is to investigate the specific influence of AlN, AlB2 and BN nanophases and their combination on the mechanical properties of the final Al-MMCs.The composites were fabricated by combination of high-energy ball milling and spark plasma sintering techniques. To form desired reinforcing phases in-situ during ball milling, powders of Al, BN, B and Li3N were used as source materials. The structures of powder mixtures and composite materials were studied by scanning and transmission electron microscopy. The influence of reinforcing phase content (1, 3, 5, and 7 wt%) on the tensile strength was investigated. In addition, the tensile tests at 500 °C were performed. X-ray and EDX analysis demonstrated that B and Li3N particles react with Al with formation of AlB2 and AlN during high-energy ball milling and sintering processes. (author)