Abstract

Overcooling of gallium–tin alloys under normal conditions has been studied by thermal analysis. The following samples have been analyzed: Ga (I); two hypoeutectic alloys: 95% Ga + 5% Sn (II), 90% Ga + 10% Sn (III); eutectic alloy: 96.3% Ga + 13.7% Sn (IV); and five hypereutectic alloys with Sn content of 20% (V), 35% (VI), 50% (VII), 80% (VIII), and pure tin (IX). A nonequilibrium state diagram of this system is constructed. Herewith, the eutectic composition does not vary and the eutectic temperature decreases to 5.5°C, that is, 26°C below that of three-phase eutectic equilibrium. The eutectic temperature does not actually vary upon a variation of cooling rates of eutectic alloy from 0.06 to 60°C/min. It has been detected that a slight decrease in overcooling is expected in the hypoeutectic region, whereas in the hypereutectic region overcooling increases while the alloy composition approaches eutectic. Activities and activity coefficients of components on the lines of equilibrium and nonequilibrium liquidus have been calculated. It is demonstrated that the activities on the lines of both equilibrium and nonequilibrium liquidus decrease in a predictable manner, and the activity coefficients increase while the composition approaches eutectic. Concentration paths of equilibrium and nonequilibrium crystallization are shown in the state diagrams.

中文翻译：

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镓锡非平衡态图的构建与分析

摘要

通过热分析研究了镓-锡合金在正常条件下的过冷。分析了以下样品：Ga（I）; 两种亚共晶合金：95％Ga + 5％Sn（II），90％Ga + 10％Sn（III）; 共晶合金：96.3％Ga + 13.7％Sn（IV）; 以及五种过锡合金，其锡含量分别为20％（V），35％（VI），50％（VII），80％（VIII）和纯锡（IX）。构造了该系统的非平衡状态图。因此，低共熔组成不变，低共熔温度降低到5.5℃，即比三相低共熔平衡温度低26℃。当共晶合金的冷却速率从0.06至60℃/ min变化时，共晶温度实际上不变化。已经发现，在亚共晶区域中，过冷度预计会略有下降，在过共晶区域，过冷增加，而合金成分接近共晶。计算了组分在平衡态和非平衡态液相线上的活度和活度系数。结果表明，平衡液相线和非平衡液相线的活度均以可预测的方式降低，并且当组成接近共晶时，活度系数增加。状态图中显示了平衡和非平衡结晶的浓缩路径。结果表明，平衡液相线和非平衡液相线的活度均以可预测的方式降低，并且当组成接近共晶时，活度系数增加。状态图中显示了平衡和非平衡结晶的浓缩路径。结果表明，平衡液相线和非平衡液相线的活度均以可预测的方式降低，并且当组成接近共晶时，活度系数增加。状态图中显示了平衡和非平衡结晶的浓缩路径。