Thermal transport properties and microstructure of the solid Bi-Cu alloys

Thermal transport properties of solid Bi-Cu alloys have been investigated over a wide composition range and temperature range ranging from 25 to 250 °C. The flash method was used to determine thermal diffusivity. Thermal diffusivity was discovered to decrease continuously with increasing temperature and bismuth content. The indirect Archimedean method was used to determine the density of the Bi-Cu alloys at 25 °C. The obtained results show that the density of the studied alloys decreases slightly as the copper content increases. Thermal conductivity of the alloys was calculated using measured diffusivity, density, and a calculated specific heat capacity. The thermal conductivity of the studied Bi-Cu alloys decreases with increasing temperature and bismuth content, similar to thermal diffusivity. SEM with energy dispersive X-ray spectrometry (EDS) and differential scanning calorimetry (DSC) were used to examine the microstructure and melting behavior of Bi-Cu alloys, respectively. The eutectic temperature was measured to be 269.9±0.1 °C, and the measured phase transition temperatures and heat effects were compared to thermodynamic calculations using the CALPHAD method.