Temperature and microstructural condition dependence for thermal diffusivity and thermal condutivity of a casting Al-Si-Cu-Mg alloy

Thermal and electrical properties as well as mechanical properties of age-hardenable Al alloys are affected, both at room and at high temperature, by their microstructural condition. This behaviour has to be considered not only for wrought but also for casting alloys, such as for the Al-7Si-0.5Cu-0.4Mg, characterized by multiple precipitation sequences investigated in the paper. In these conditions the temperature dependence of thermophysical properties, generally obtained performing tests during isochronal heating, is not only related to the initial microstructural condition, but also to heating rate, a test parameter whose range is often limited by testing methodologies and equipments. These effects have to be taken into account in cases where a multipurpose material characterization or a comparative analysis of result is intended to interpret microstructural changes. Ex-situ tests can help the separation of microstructural changes effect from temperature-related ones. Examples of the combined techniques and analyses are illustrated.