The microstructure of composite materials in the EN AW-2024 alloy matrix reinforced by α-Al2O3 particles

The paper presents the results of investigations into the microstructures of composite materials produced by pressure infiltration of preforms of ceramic α-Al₂O₃ particles with aluminium alloy EN AW-2024. In particular, the quality of the bonds at the interphase boundaries of matrix-ceramic particles was evaluated using microscopy investigations. It was found that silica (SiO₂) used for bonding alumina particles in the preform causes an enrichment of the matrix in silicon (Si), which partly diffuses to aluminium alloy, yet remains in the matrix in the form of SiO₂ concentrations, especially within ceramic particles with a high degree of agglomeration. The infiltration of open pores of ceramic preforms with EN AW-2024 alloy of limited flowing power hinders the infiltration process, resulting in local porosity. The propagation of cracks in the composite material after tests for mechanical properties occurs mainly along the interphase boundaries of the matrix-particle, especially in places with an increased residual amount of silica (SiO₂) in the matrix. On the surfaces of the fractures ceramic particles of the α-Al₂O₃ reinforcement are observed, they form a strong adhesive bond with the matrix and crack during the formation of scrap metal.

Download 4.29 MB >>