Microstructures and Enhanced Mechanical Properties of (Al3ti+Al2o3)/Al-Si Composites with Co-Continuous Network Structure Prepared by Pressure Infiltration

Abstract

The (Al 3 Ti+Al 2 O 3 )/Al-Si composites with three-dimensional co-continuous network structures were fabricated by a pore-forming agent and the pressure infiltration technique. The effect of Al 3 Ti content on the mechanical and wear properties of the developed composites was investigated. Al 2 O 3 (alumina) formation, fracture, and wear mechanism of the composites were also analyzed. The results demonstrated that the 20 vol.% (Al 3 Ti+Al 2 O 3 )/Al-Si composites led to the optimal mechanical properties, whose compressive and flexural strengths were 585 MPa and 489 MPa, respectively, which are 64.8 % and 46.0 % higher than that of the matrix. The specific wear rate of composites (16.5×10−14 m3/Nm) is 79 % lower than that of the matrix. Further increasing the Al3Ti content, the network structure is completed, and the wear resistance properties are improved while the mechanical properties are decreased. In addition, the granular Al 2 O 3 particles scatter around Al 3 Ti phases which are synthesized in-situ during the sintering process. The enhanced mechanical properties may primarily be attributed to the three-dimensional co-continuous network structure of the Al 3 Ti and Al 2 O 3 phases.

Keywords: Co-continuous network structure, (Al3Ti+Al2O3)/Al-Si composites, Microstructure, Mechanical Properties, Pore-forming agent, Pressure infiltration