The Effect of Nickel on the Thermal Conductivity of Al-Si Cast Alloys

In this study the effect of Ni on the thermal conductivity of hypoeutectic Al-Si cast alloys is described. The Ni-containing alloys are considered as a two-phase system, which consists of a ‘matrix’, composed of α-solid solution, eutectic Si, primary Al₁₂(Fe,Mn)₃Si₂ phases and secondary Mg₂Si-precipitates, and Ni-containing intermetallic phases incorporated in this ‘matrix’. With increasing Ni-content the volume fraction of second phases increases, whereby the characteristics of the material change from a ‘homogeneous matrix’ to a ‘particle-reinforced’ two-phase composite. The thermal conductivity data are discussed on a systematic basis of thermodynamic calculations and compared to data for the electrical conductivity as well as theoretical models for the thermal conductivity of heterogeneous solids.