Enhanced thermal conductivity and tensile strength of Al-17Si-3.5Cu with SiC-nanoparticle addition.

The morphology and size of primary Si has a significant influence on the thermal conductivity (TC) and strength of Al-17Si-3.5Cu. In this study, the effect of a 1-3 wt% SiC nanoparticle (SiC) addition on TC and tensile strength of Al-17Si-3.5Cu was investigated. Nanoparticles distributed at the interface between primary Si and Al led to a significant refinement of primary Si; for example, a primary Si size of 2 μm with 3 wt% SiC addition was achieved. TC of SiC/Al-17Si-3.5Cu improved with an increase in nanoparticle content. Nanoparticles distributed at the interface between Si and Al reduced the interfacial thermal resistance. Thus, the effective TC of eutectic Si increased. Owing to the refinement of the primary Si and the increased interfacial thermal resistance, originating from the high content of SiC at the interface, the effective TC of primary Si decreased. Compared with Al-17Si-3.5Cu, contribution to the improvement of the TC of SiC/Al-17Si-3.5Cu resulted mainly from eutectic Si. Due to the refinement of primary Si, the tensile strength of SiC/Al-17Si-3.5Cu improved with an increase in SiC content. When the SiC content was 3 wt%, the yield strength, ultimate tensile strength and elongation of SiC/Al-17Si-3.5Cu were ∼176 MPa, 418 MPa and 7%, respectively, which were improved by 37.5%, 53.7% and 218%, respectively, when compared with Al-17Si-3.5Cu.