In-situ synthesis and microstructural evolution of a SiC reinforced Al-50Si composite exhibiting exceptional thermal properties

作者：Chao Ding, Qi Shi, Huali Hao, Rui Ma, Shukui Li, Changqing Ye, Changyang Yu, Xin Liu, Peng Yu, Shulong Ye · 发表于：Materials & Design · 年份：2024 · DOI：10.1016/j.matdes.2024.113422 · 被引用次数：12 · 研究领域：Aluminum Alloys Composites Properties、Advanced ceramic materials synthesis、Intermetallics and Advanced Alloy Properties

• Carbon nanotubes (CNTs) are grown on the surface of Al-50Si powder via in-situ chemical vapor deposition. • A SiC reinforced Al-50Si composite with low thermal expansion and high thermal conductivity is achieved by hot extrusion and subsequent heat treatment. • Microstructural evolution during the in-situ SiC formation is thoroughly studied. • The influences of in-situ SiC formation on the thermal and mechanical properties of Al-50Si alloy are revealed. Incorporating carbon nanotubes (CNTs) into Al-Si alloy to prepare in-situ SiC/Al-Si composites enhances thermal conductivity (TC) and reduces the coefficient of thermal expansion (CTE). However, challenges include CNTs aggregation and uneven SiC distribution. This study uses fluidized bed chemical vapor deposition (FBCVD) to achieve uniform CNTs coverage on Al-50Si powder. Subsequent powder hot extrusion and heat treatment above the eutectic temperature enable a gradual reaction between CNTs and Al/Si atoms, resulting in uniformly dispersed SiC within the SiC/Al-50Si composite. The formation mechanism of in-situ SiC particles and their impact on the microstructure, thermal and mechanical properties of the composite are further investigated. The formation process involves a two-step chemical reaction: lamellar Al 4 C 3 phases transform into lamellar eutectic SiC + Al phases, which then transition into polyhedral SiC particles through epitaxial growth. This in-situ formation of SiC particles also impedes Si growth during heat ...