Effects of Sc Content on Microstructure and Thermophysical Properties of Al-xSc Alloys

Abstract:

AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters. The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications. Al-xSc alloys (x=5, 10, 15, 20, 25, at%) were prepared by vacuum induction melting, whose purity is mainly determined by the raw materials and the production process. The results reveal that as the Sc content increases from 5at% to 20at%, the volume fraction of the Al₃Sc phase in the alloy increases from 26.9% to 80.2%, and the average grain size of the Al₃Sc phase increases from 12.9 μm to 67.7 μm during this period. Additionally, both the coefficient of thermal expansion (CTE) and thermal conductivity (TC) of AlSc alloys exhibit a downward trend. Based on experimental data and first-principles calculations, the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys. The optimal characteristic parameter (k₀) of the Turner model is determined to be 50. The model predictions align well with the experimental results.