Influence of reinforcement with multimodal distribution on thermophysical properties and fracture behavior in Al-Si/SiC composites infiltrated under super-gravity field

Abstract

Super-gravity field assisted infiltration is reported as an effective method to obtain the nearly fully-dense Al-Si/SiC composites at relatively lower temperature, which inhibit the interfacial reaction and result in the enhancement of thermal conductivity (TC) and bending strength (BS). Currently, SiC reinforcement with multimodal distribution was designed to further enhance the TC and BS with lower coefficient of thermal expansion (CTE) of Al-Si/SiC composites. For the composites with monomodal SiC distribution, enlarging the size of SiC results in an enhancement of TC with the sacrifice of BS. Interestingly, for the composites with multimodal SiC distribution, the TC can be stabilized within an extended range (175-187W/m·K at 373K) with reduced CTE and higher BS. When the large to small size ratio was 1:2, the optimal comprehensive properties (CTE: 8.66×10-6K-1 ranged from 323 to 373K, TC: 179.2W/m·K at 373K, BS: 309 ± 9MPa) can be obtained. Hasselman-Johnson, Turner, and Kerner models are established to better understand the thermophysical properties, while the fracture behavior is discussed based on the track of crack propagation.