Microstructure and mechanical behavior of AA2024 aluminum matrix composites reinforced with in situ synthesized ZrB₂ particles

Preparing aluminum matrix composites (AMCs) using in situ method results in many desirable benefits. This paper is focused on preparing AA2024/(0, 2.5, 5, 7.5 and 10 wt%) ZrB₂ AMCs by Al–K₂ZrF₆–KBF₄ reaction system. The inorganic salts were added to molten aluminum alloy at an elevated temperature of 850^OC. The prepared AMCs were studied by applying conventional microcopy and advanced characterization techniques. XRD peaks confirmed the successful synthesize of ZrB₂ particles. No other phases such as Al₃Zr and AlB₂ were detected in appreciable quantity. There was a refinement of grains in the composite due to ZrB₂ particles. Two kind of distribution was observed in the micrographs. Particle clusters trapped within the grain boundaries were observed with increased weight fraction of particles. ZrB₂ particles were observed to be sub–micron and nano level in size and characterized by proper interfacial bonding with the aluminum matrix. The thermal misfit generated lot of strain fields in the aluminum matrix. The mechanical properties were improved remarkably by the incorporation of ZrB₂ particles and the possible strengthening mechanisms were discussed.