Strength Properties of Alumina Fiber Reinforced Aluminium Matrix Composites at Elevated Temperature

The influence of fibre volume and temperature on tensile, bending and compression strength of short planar randomly distributed fibre reinforced AC 44200 aluminium alloy matrix has been tested and analyzed. First, porous (80-90%) alumina Saffil fibre preforms characterized proper permeability and strength were prepared for infiltration with molten metal. Using direct squeeze casting method, with pressure 100MPa, composite materials were produced. Microstructure observations revealed good interface between fiber and matrix, without chemical reaction products and typical in such systems spinel MgAl₂O₄. Though, after preparation of preform, when silica binder were used thin, 70-100nm homogenous layer of amorphous SiO₂ coated fibers. Distinct improvement of strength properties with increase of fibre content was observed. At 20 vol.% of fibre increase of tensile, bending and compression strength amounted ca. 60%, 50% and 30% correspondingly. At higher temperature (200-300°C) all tested properties decreased to the level of strength of unreinforced matrix at ambient temperature.