Thermodynamics of Al — Si and Al — Ge — Si liquid alloys: Enthalpies of formation by high temperature calorimetry

Abstract

Bildungsenthalpie / Fliissige Legierungen / Hochtemperatur-Kalorimetrie / Metalle / ThermodytiamikThe enthalpies of formation of Al -Si and Al-Ge -Si liquid alloys were investigated by high temperature calorimetry. A new mixing and stirring device was designed in order to take into account the physicochemical properties of the metals involved. -The enthalpy of formation of the ternary alloys were found satisfactory using the Kohler's equation; the quasi-ideality assumption for the binary Ge-Si revealed verified within the experimental accuracy.

Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl)

“…This might explain why these results were not considered in thermodynamic calculations of [ 66 , 99 , 105 ]. The calculated enthalpy of mixing in the present work, taking into account all the available data sets, agree with the experimental data of [ 102 ] in the 58–100 at % Al range and consistent with the calculations of [ 58 ] in the full composition range at 1427 °C. Thus, the calculations made in this work are more reliable for thermodynamic modelling purpose.…”

“…In Figure 6 a, the calculated enthalpy of mixing of the liquid phase by Murray and McAlister [ 58 ] at 1427 °C agree with the reaction calorimetric result of Bros et al [ 102 ] within ±225 J·mol −1 only at mid-composition, but differ 900 J·mol −1 from the results of Korber et al [ 58 ] and 500 J·mol −1 from Gizenko et al [ 103 ]. In contrast, Tang et al [ 99 ] gave higher weight to the experimental results of Rostovtsev and Khitrik at 1600 °C [ 104 ].…”

“… ( a ) Calculated enthalpy of mixing of the Al-Si liquid; ―: [ 99 ] at 1600 °C; ○: [ 104 ] at 1600 °C; □: [ 103 ] at 1547 °C; Δ: [ 102 ] at 1427 °C; -·-·-: [ 58 ]; -----: [ 66 ]; ····· : [ 105 ] at 1427 °C and ( b ) Calculated activity of Al and Si in the Al-Si liquid at 1427 °C; -----: [ 99 ] at 1600 °C; ○: [ 106 ]; □: [ 107 ] and Δ: [ 100 ] at 1427 °C; ■: [ 103 ] at 1547 °C; ▲: [ 108 ] at 1700 °C. …”

An angular embedded atom method interatomic potential for the aluminum–silicon system

“…It should be stressed, however, that the experimental curve depicted in the figure is an assessment of several experiments [59], but in fact there is considerable variation in the experimental values [60]. For example, comparison of the results reported from [61] with [62] shows that using the same experimental technique, and with only a 4 K difference in temperature, H mix is 3.1 kJ mol −1 more negative in [62]. Even a positive enthalpy of mixing has been reported [63,64].…”