2018 Volume 59 Issue 5 Pages 724-729
Al/Si composites with 27 mass % Si were prepared by powder metallurgy, and then were multi-pass hot-rolled and, the deformation reduction was 8%–15% for each pass. An intermediate annealing treatment with the holding time of 30 min was prepared for the next rolling process until the rolling reduction was 70%. At last specimens were annealed at 400°C for 6 h followed by air cooling. Microstructures and properties of the composites were investigated. The results show that the prepared composites consist of Al and Si phases, and Si particles distribute uniformly in Al matrix. During the rolling process, the deformation behavior of the composites is sustained by Al matrix, while Si particles are not deformed. The coefficient of thermal expansion (CTE), the thermal conductivity (TC) and the mechanical strength of the composites are also improved by the rolling process. The TC are improved and the mechanical strength are reduced due to the decrease of residual stress after annealing treatment. The annealed composite with the rolling reduction of 70% shows comprehensive properties with the CTE of 17.61 × 10−6/K (25–200°C), the TC of 169 W/(m·K), the tensile strength of 137 MPa and the bending strength of 228 MPa.
