Binary phase diagrams - understanding the eutectic point

In summary, the binary phase diagram represents the materials at 100% on each end, with the middle being a 50-50% mixture. The eutectic point on the diagram is the ideal point that marks the lowest temperature at which the solution can be entirely liquid. It is determined by the percentages of each material and is a tested value. The avatar of the expert is meant to represent chemical-mechanical coupling.
  • #1
Femme_physics
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1) So, does the binary phase always represent the materials 100% on each end? That is to say, if you have lead and antimony, the right side will always represent 100% of one of the two, and the other side will present 100% of the other. If we look in the middle of the diagram, it's 50-50%, right?

2) The eutectic point is basically an ideal point on the diagram that represents the lowest cooling point based on the certain percentages of each materials. This is a tested value.


Do I have it correctly?
 
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  • #2
Femme_physics said:
1) So, does the binary phase always represent the materials 100% on each end? That is to say, if you have lead and antimony, the right side will always represent 100% of one of the two, and the other side will present 100% of the other. If we look in the middle of the diagram, it's 50-50%, right?

Yes, but it might be 50%-50% by weight percent or by atomic percent. A complete phase diagram will tell you which one is being used. Some diagrams have one scale on the bottom x axis and the other on the top (see http://www.interfluxusa.com/images/Eutectic_graf.jpg", for example).

Femme_physics said:
2) The eutectic point is basically an ideal point on the diagram that represents the lowest cooling point based on the certain percentages of each materials. This is a tested value.

The eutectic point is the temperature and composition that marks the lowest temperature at which the solution can be entirely liquid.
 
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  • #3
Yes, but it might be 50%-50% by weight percent or by atomic percent. A complete phase diagram will tell you which one is being used. Some diagrams have one scale on the bottom x-axis and the other on the top (see here, for example).

Ah, I see.

The eutectic point is the temperature and composition that marks the lowest temperature at which the solution can be entirely liquid.

Is a better way to put it :)

Thanks a bunch Mapes.

BTW - I've been wondering for a while now, what does your avatar represent?
 
  • #4
Femme_physics said:
BTW - I've been wondering for a while now, what does your avatar represent?

It's meant to represent chemical-mechanical coupling: a melding of schematics for forces, springs, atomic force microscopy, nanoindentation, mortar & pestle, and ligand-receptor binding. Thx for asking!
 

What is a binary phase diagram?

A binary phase diagram is a graphical representation of the phases present in a two-component system at different temperatures and compositions.

What is the eutectic point on a binary phase diagram?

The eutectic point is the lowest temperature at which a liquid phase can exist in equilibrium with two solid phases in a binary system. It represents the composition at which the two components have the same melting point.

How is the eutectic point determined on a binary phase diagram?

The eutectic point can be determined by tracing the liquidus and solidus lines on the diagram to where they intersect. This point represents the composition and temperature at which the eutectic reaction occurs.

What is the significance of the eutectic point on a binary phase diagram?

The eutectic point is important because it represents the lowest temperature at which a mixture of two components can melt or freeze completely. It also indicates the composition at which the two components are most soluble in each other.

How can binary phase diagrams be used to predict the behavior of materials?

Binary phase diagrams can provide valuable information about the phases that will be present at different compositions and temperatures. This can be used to predict the behavior of materials such as the formation of solid solutions, the formation of eutectic mixtures, and the effects of cooling and heating on a material.

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