相图中自由度的理解

Understanding of Degree of Freedom in Phase Diagram

相平衡相关知识在日常生活、工业生产中被广泛应用。与材料、冶金、化工等学科交叉融合,在物理化学课程中是极具实际应用性的一章。但学生在利用相律公式计算相图中的自由度过程中普遍存在一些疑惑,如自由度怎么计算、自由度的数值具体代表的是什么独立变量等问题。针对这些问题,以单组分和二组分的相图为例,运用相律公式计算相图中的相区、相线、特殊相点处的自由度,指明自由度所代表的意义,并讨论了其中常见的一些问题。

The knowledge of phase equilibrium is widely used in daily life and industrial production.It is a practical application chapter in the course of Physical Chemistry,which is the interdisciplinary fusion with materials,metallurgy,chemical engineering and other subjects.However,students generally have some doubts in the process of calculating the degree of freedom in the phase diagram by using the phase rule,such as how to calculate the degree of freedom,what independent variable does the value of the degree of freedom represent.As for the questions,the degree of freedom of phase region,phase line and special phase point in the phase diagram were calculated by using the phase rule formula with the phase diagrams examples of one-component and two-component.The meanings of the degree of freedom in different phase diagrams were pointed out.Moreover,the common problems were discussed and pointed out.