Specific heat of ternary Ag–Si–Ge alloys from 123 K to high temperatures: experiment and prediction

Abstract

The knowledge of specific heat for Ag–Si–Ge alloys in a broad temperature range would facilitate their practical applications in various branches of engineering. In this work, differential scanning calorimetry measurements were executed to determine specific heat of Ag–Si–Ge alloys from 123 K to high temperatures. For binary alloys, distinct troughs of specific heat are observed at eutectic Ag89Si11 and Ag75Ge25, when temperatures are larger than 500 K. Furthermore, specific heat of ternary Ag–Si–Ge alloys was predicted by four candidate principles based on the binary alloy’s data. Accordingly, the specific heat of 15 compositions of ternary Ag–Si–Ge alloys was determined to evaluate the predicted value. It is found that specific heat increases linearly with the rising Ag and Ge content in Si-rich alloys at low temperatures. Besides, alloys around Si–Ag75Ge25 pseudobinary line in Ag-rich area exhibit much lower specific heat at high temperatures. According to the comparison between measured and predicted specific heat of ternary alloys, the interpolation which employs data of pure elements, hypo-/hypereutectic alloys and the eutectic points, provides highest accuracy, especially at high temperatures. This rule may be applied to other eutectic systems.