文档介绍：Chapter Four Phase diagram
basic types of binary system phase diagram
basic types of binary system phase diagram
ternary phase diagram
2017/11/11
Chapter Four Phase diagram
2017/11/11
basic types of binary phase diagram
rules
rule
Phase rule is the rule which studies the variations of substance ponents and other parameters in thermal can be described as follows:
F=c-p+2(temperature、pressure)
In which,
F-degree of freedom;p-phase number;c-ponent number.
Because steel-making metallurgy mainly studies phase equilibrium in stabilized pressure system, pressure is constant, thus,F=c-p+1
binary system:F=3-p;
Ternary system:F=4-p。
rule
When the key parameters of a system keep changing continuously, and the phase number is fixed, then the property of phase and the whole system would change continuously; if the phase number changes,so does the degree of freedom, then the property of phase and the whole system would change dramatically.
rule
As to a given thermodynamics system, balanced phases have corresponding geometrical elements in phase diagram.
2017/11/11
basic types of binary phase diagram
~ diagram and its application(Ellingham diagram)
As to the reaction of element M and oxygen ,there is a standard form(that is all the elements react with ):
=
= =
in order to cotrast oxide,Ellingham obtained relationship between and , and draw of all the elements reacting with on a diagram. As showed in 2-1
2017/11/11
basic types of binary phase diagram
Ellingham diagram’s thermodynamics characteristics
From the point of thermodynamics ,all the reactions in the diagram have two characteristics mon:
1) The lower the beeline is,the stable the oxide is, or the harder the oxide would be deoxidize ;
2) At the same temperature,if several elements meet at the same time,the oxidation sequence will be: the lowest element in Ellingham diagram will be oxidized first, for example:at