The mechanical properties of Al2O3/aluminum alloy A356 composite manufactured by squeeze casting

Porous aluminum oxide (Al2O3) preforms were formed by sintering in air at 1200 °C for 2 h. The A356 aluminum alloy was infiltrated into the preforms in order to fabricate Al2O3/A356 composites with different volume content of A356 by squeeze casting. The volume contents of A356 alloy in Al2O3/A356 composites were 5–40 vol.%. For the corresponding composites, the four-point bending strength of the composites changed from 397 to 443 MPa, the hardness decreased from 1109 to 227 HV and the fracture toughness increased from 4.97 to 11.35 MPa m1/2. One can fine three toughening mechanisms, crack bridging, crack deflection and crack branching in the composites on SEM micrograph.