In situ (Al₃Zr + Al₂O_3np)/2024Al metal matrix composite with novel reinforcement distributions fabricated by reaction hot pressing

In situ hybrid (Al₃Zr + Al₂O₃np)/2024Al metal matrix composites with unique controlled reinforcement distributions were fabricated using low energy ball milling and reactive hot pressing. The reaction system between 2024Al and ZrO₂ was studied using differential thermal analysis (DTA). In situ formed aluminium oxide (Al₂O ₃) and zirconium tri-aluminide (Al₃Zr) with varying morphology and sizes were produced under different fabricating conditions. Al₃Zr with varying morphologies such as particle, plate and flakes were observed. With a total 10 vol.% of reinforcements, the composite containing a threedimensional network of closely spaced in situ synthesized Al3Zr and Al2O₃ particles had a YS of 175 MPa and a UTS of 261 MPa, effectively strengthening the 2024Al matrix. The effect of different sintering conditions on the microstructure and tensile properties of the composite was systematically investigated.