Al-Mg合金热力学性质的计算

以Ｍｉｅｄｅｍａ二元合金生成热模型为基础，结合一些基本热力学关系式，利用元素的基本性质计算了１０７３Ｋ下ＡｌＭｇ合金中组元Ｍｇ的活度及合金的部分热力学函数（ΔＨ，ＧＥ，ＳＥ）。结果表明，在１０７３Ｋ下，溶液中Ｍｇ的行为相对拉乌尔定律存在较大的负偏差；混合焓、过剩自由能与过剩熵在整个浓度范围内均为负值；混合焓最小值为－１１．４ｋＪ／ｍｏｌ，过剩自由能最小值为－８．７７ｋＪ／ｍｏｌ，过剩熵的绝对值较小，接近零。计算结果与实验数据吻合较好。

CALCULATION OF THERMODYNAMIC PROPERTIES OF LIQUID AlMg ALLOYS

Based on the Miedema's model for calculating the formation heat of binary system, the activity of Mg in AlMg alloys and some of the thermodynamic functions (H, GE, SE) at 1 073 K of the alloy were calculated by taking use of the basic properties of the elements (electronic negativity , electronic density nws, mol volume V). The results indicated that the Mg concentration shows a negative deviation from Rault's Law; mixing enthalpy, excess free energy and excess entropy are all negative in the whole range of concentration; the minimum value of mixed enthalpy is -11.4 KG-*6]kJmol-1, the minimum excess free energy is -8.77 kJmol-1, the absolute value of excess entropy appoaches zero. The calulated results showed this method is feasible and accord with the experimental data perfectly.