Effects of porosity on the thermal properties of a 380-aluminum alloy

Effective values of the thermal diffusivity, specific heat, and thermal conductivity of a porous 380-aluminum alloy prepared by melting in a gas-fired furnace, were determined as a function of the volume fraction of porosity. For that, photoacoustic, differential calorimetric, density, and image analyzer measurements were done. Thermal conductivity and specific heat capacity decrease with the increase of porosity, whereas the thermal diffusivity shows less dependence. Among the effective models for analysis of the thermal conductivity of a two-phase system, the Maxwell model best fits the experimental data, implying a homogenous distribution of the pores in the aluminum-alloy matrix.