中文摘要：

以三元系等活度线计算机绘制过程中出现的锯齿形问题,抓住常见等活度线的一般规律,提出一种新的三元系等活度线的计算方法。通过转换浓度变量,构造一组在计算范围内单调的方程,确保了绘图不出现锯齿形。此法原理简单,可用于各种热力学模型的等活度线计算。用于SReM热力学模型,并建立等活度图绘制程序。程序具有界面友好、应用灵活、实用性强的特点。用之于绘图,表明本文提出的方法,可有效避免出现锯齿形。

英文摘要：

In order to avoid zigzag, a new method for drawing iso-activities diagram of ternary system was proposed, according to the general rules of the iso-activities diagram. Some monotonic equations were concluded by converting variables of concentration to a new form, which make sure zigzag are not shown in our situation. A program of SReM thermodynamic model with the method was applied to was writen by using VC ＋ ＋. net, which is interface-friendly and easily operated. And iso-activities diagrams of Mn-Si-Fe and FeO-SiO2-CaO were ploted with the program. The results indicate that the program can precisely calculate iso-activities lines and effectively avoid the zigzag. Therefor, this method can be widely used in various of thermodynamic models when the relationship of variables were made.