Al-Mg-Li三元合金表面张力的估算

运用表面张力计算公式Butler方程，与过剩吉布斯自由能结合，计算了973 K温度下Al?Mg, Al?Li和Mg?Li二元体系的表面张力。结果表明，在铝熔体中分别加入金属镁或锂，合金表面张力随其含量增加而降低；在镁熔体中加入金属锂，合金表面张力随锂含量增加而降低。以此为基础，利用Chou模型计算得Al?Mg?Li三元合金的表面张力为0.326?0.851 N/m，随铝或镁含量增加表面张力增大，随锂含量增加表面张力减小。

Estimation of surface tension of Al-Mg-Li ternary alloy

The characteristics of the aluminum?magnesium alloy are light, good mechanical properties, corrosion resistance, low energy consumption, green and cheap, which make it more and more popular. Currently, aluminum?magnesium alloy has been widely used in automobile manufacturing, doors and windows sheet, medical apparatus and instruments, aerospace and marine transportation and other fields. The performances of aluminum?magnesium alloy are mainly affected by its thermophysical properties. It is important to study the surface properties involved in the presence of all liquid processes in the industrial process than other thermophysical properties. Surface tension, one of the key influence factors to the reaction of multiphase system and mass transfer, is a significant property of liquid metal, which plays a decisive role in the crystal growth of alloys, the microscopic appearance of welded joints and the cracking of metals during solidification. However, it is difficult to measure the surface tension at high temperature, only a small number of reference data can be referred to. In this work, the surface tensions of the Al?Mg, Al?Li and Mg?Li binary systems at 973 K were estimated on the basis of Butler?s equation, in combination with excess Gibbs energies, and the factors influencing surface tension were studied. The calculation results showed that the surface tension of aluminum melts decreased with the increase of magnesium or lithium content, the surface tension of magnesium melt decreased with increasing additions of lithium. On this basis, the surface tension of Al?Mg?Li ternary alloy at 973 K was calculated by using Chou model. The calculation results indicated that surface tension of Al?Mg?Li ternary alloy was approximately in the range of 0.326?0.851 N/m and its surface tension increased as the aluminum or magnesium content increased. Further, the essential factors that influence the surface tension were obtained. The results have important theoretical significance and practical application value for engineering research.