Other much more complex types of phase diagrams can be constructed, particularly when more than one pure component is present. In that case concentration becomes an important variable. Phase diagrams with more than two dimensions can be constructed that show the effect of more than two variables on the phase of a substance. Phase diagrams can use other variables in addition to or in place of temperature, pressure and composition, for example the strength of an applied electrical or magnetic field and they can also involve substances that take on more than just three states of matter.
The iron–iron carbide (Fe–Fe3C) phase diagram. The percentage of carbon present and the temperature define the phase of the iron carbon alloy and therefore its physical characteristics and mechanical properties. The percentage of carbon determines the type of the ferrous alloy: iron, steel or cast iron
A phase diagram for a binary system displaying a eutectic point.
One type of phase diagram plots temperature against the relative concentrations of two substances in a binary mixture called a binary phase diagram, as shown at right. Such a mixture can be either a solid solution, eutectic or peritectic, among others. These two types of mixtures result in very different graphs. Another type of binary phase diagram is a boiling point diagram for a mixture of two components, i. e. chemical compounds. For two particular volatile components at a certain pressure such as atmospheric pressure, a boiling point diagram shows what vapor (gas) compositions are in equilibrium with given liquid compositions depending on temperature. In a typical binary boiling point diagram, temperature is plotted on a vertical axis and mixture composition on a horizontal axis.
Boiling point diagram
A simple example diagram with hypothetical components 1 and 2 in a non-azeotropic mixture is shown at right. The fact that there are two separate curved lines joining the boiling points of the pure components means that the vapor composition is usually not the same as the liquid composition the vapor is in equilibrium with. See Vapor-Liquid Equilibrium for more information.
In addition to the above mentioned types of phase diagrams, there are thousands of other possible combinations. Some of the major features of phase diagrams include congruent points, where a solid phase transforms directly into a liquid. There is also the peritectoid, a point where two solid phases combine into one solid phase during cooling. The inverse of this, when one solid phase transforms into two solid phases during heating, is called the eutectoid.
A complex phase diagram of great technological importance is that of the iron-carbon system for less than 7% carbon (see steel).
The x-axis of such a diagram represents the concentration variable of the mixture. As the mixtures are typically far from dilute and their density as a function of temperature is usually unknown, the preferred concentration measure is mole fraction. A volume based measure like molarity would be unadvisable.
Crystal phase diagrams
Polymorphic and polyamorphic substances have multiple crystal or amorphous phases, which can be graphed in a similar fashion to solid, liquid, and gas phases.
Log-lin Pressure-temperature phase diagram of water. The Roman numerals indicate various ice phases.
1 komentar:
It is known that many kinds of structures that may occur in an alloy. Because many properties of materials depend on the type, amount / number and shape of the phase that occurs, then the properties will change if the above change. Therefore please be aware of an alloy on how a phase condition can occur and the conditions of how a phase change will occur.
A diagaram phase, ideally would describe the relationship between the phases, composition and temperature, in equilibrium (equilibrium, a condition in which no change is dependent on time). Equilibrium condition can be approximated by a heating and cooling is very slow, sehungga when there are changes that have occurred then the phase will be more time to reach equilibrium.
Diagram of a simple example with hypothetical components 1 and 2 in non-azeotropic mixture appear on the right. The fact that there are two separate curved lines connecting the boiling points of pure components means that the composition of the vapor is usually not the same as the composition of the vapor in equilibrium with the liquid. See Vapor-Liquid Equilibrium for more information.
In addition to the above mentioned types of phase diagrams, there are thousands of other possible combinations. Some of the main features of the phase diagram includes a congruent point, where the solid phase changes directly into a liquid. There is also peritectoid, the point at which two solid phases merge into one solid phase during cooling. The opposite of this, when one solid phase into two solid phase change during heating, the eutectoid called.
In the article is less clear about the images that exist in the above article, so it was not clear about the variables used in the phase diagram itself. such as the variable "a", "A" and other variables. This article also does not include how to calculate the alloy phase, phase and long term weight phase that should be important to know.
very insightful as well with the above article, the article explains that the two mixtures can produce different graphs. Another type of binary phase diagrams are boiling point diagram for mixtures of two components, i. e. chemical compounds. For two particular volatile components at a specific pressure such as atmospheric pressure, the boiling point diagram shows what vapor (gas) composition in equilibrium with the liquid composition is given depends on the temperature.
at least the material above is very useful to explain the material approaches the binary phase diagram .......
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