Pressureless infiltration of liquid aluminum alloy into SiC preforms to form near-net-shape SiC/Al composites

SiC/Al composites with uniformly distributed SiC particles were fabricated by pressureless infiltration of liquid AlSi7Mg alloy into SiC preforms with different porosity derived from SiC powders. The linear expansion of SiC preforms without any deformation was about 4% due to the oxidation of SiC powders during the sintering process. SiC preforms had no change in both shape and dimensions after infiltration so that near-net-shape composites were achieved. As SiC volume fraction varies from 39% to 62%, the thermal conductivity of SiC/Al composites with bending strength beyond 360 MPa and elastic modulus beyond 140 GPa varies from 146 to 118 W m(-1) K-1 at room temperature, and the mean linear coefficient of thermal expansion from room temperature to 373 K varies from 10 X 10(-6) to 7.69 x 10(-6) K-1, agreeing better with the Turner's model. (C) 2007 Elsevier B.V. All rights reserved.