Effect of presence and type of particulate reinforcement on the electrical conductivity of non-heat treatable aluminum

In the present study, the effect of presence and type of reinforcing particulates (C and SiC) on the electrical conductivity of 99.5% non heat treatable aluminum was investigated. The synthesis of the unreinforced and reinforced samples was carried out using disintegrated melt deposition route. Microstructural characterization studies conducted on the unreinforced and reinforced samples revealed the presence of columnar-equiaxed microstructure and unconnected porosity. Energy dispersive spectroscopic analysis conducted in the near vicinity of SiC particulates revealed a more pronounced segregation of silicon when compared with C particulates. The results of electrical properties measurements indicate that the presence of reinforcing particulates degrade the electrical conductivity of the metallic matrix and that the C particulates besides their higher volume fraction degrade the electrical conductivity of the aluminium to a lesser extent when compared with SiC particulates. The electrical conductivity results obtained in this study are correlated with the particulatesʹ associated microstructural and constitutional changes in the metallic matrix. A new rule of mixture is proposed that incorporates the particulatesʹ associated change in matrix microstructural features as a necessary criterion to compute the electrical conductivity of the reinforced metallic matrices. The electrical conductivity results obtained using modified rule of mixture accords well with the conductivity trend proposed by the Kernerʹs model and the experimental results obtained in the present study. The electrical conductivity results, however, indicate that the variation in electrical conductivity as a result of the presence of reinforcing particulates may not necessarily follow the trend predicted by the classical Rayleigh-Maxwell equation.