Sc含量对Al-xSc合金微观组织及热物性的影响

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

摘要:

AlSc合金靶材制备的AlScN压电薄膜是5G射频滤波芯片的核心材料。AlSc合金的热物性及其焊接工艺与应用之间存在密切联系。通过真空熔炼法制备了不同Sc含量的Al-xSc（x=5，10，15，20，25，at%）合金，其纯度影响因素主要来源于Sc原材和生产过程。结果表明，随着Sc含量由5at%增加至20at%，合金中Al₃Sc相体积分数由26.9%增加至80.2%，平均尺寸由12.9 μm增加至67.7 μm；AlSc合金的线性热膨胀系数和导热率均呈现下降的趋势。基于实验和第一性原理计算结果，有效介质模型和Turner模型能够分别有效预测Al-xSc合金的导热系数和热膨胀系数，其中Turner模型特征参数k₀最优取值为50，模型预测值与实验值相吻合。

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.