Solution
So I realized after I posted my question in the previous post that the solution is quite complex. The phase diagram that I included is a very complex diagram. A simpler diagram would make things clearer I think. The melting regime can be found if you imagine a vertical line at 60% Chromium (Cr). The last area (as you go up) that is enclosed by dotted lines (triangular shaped area) is the region in which Liquid is stable at the same time that solid is stable. If you think about water, this only happens at a single temperature. When ice melts, liquid water forms around it and they are in equilibrium (if maintained at a constant temperature). It is possible to have a glass of 32 degree water and 32 degree ice. It is not possible (under normal conditions) to have 35 degree water and 35 degree ice at equilibrium. The Aluminum-Chromium system is different.
A single element or molecule will have a single melting point. For example: water, iron, tin, etc. When you mix them, the individual elements fight for dominance (so-to-speak). The solid and liquid phases in this case have their own regions of stability. These regions are determined by composition, temperature, pressure, and various energy concerns. At 60% Cr, both can be stable (under special circumstances). Much like 2 large crowds of people with 2 different opinions, a truce can be found. An agreement is sometimes made out of necessity. With the Liquid and Solid from the diagram, this truce allows both to be present at the same time. The proportion of solid-to-liquid will vary, however, based on the relative strengths of the two phases that vary with temperature. In this case, as temperature is increased, Liquid becomes stronger and will dominate. Eventually all the solid will be converted into liquid. This process occurs over the full 150 degree celcius melting range.
This is a fairly simple explaination, but hopefully you get the idea. Maybe we can get Krista to tell us what she does. Her work is very interesting. She works with E. Coli, DNA, kidney cells, and chemistry.
A single element or molecule will have a single melting point. For example: water, iron, tin, etc. When you mix them, the individual elements fight for dominance (so-to-speak). The solid and liquid phases in this case have their own regions of stability. These regions are determined by composition, temperature, pressure, and various energy concerns. At 60% Cr, both can be stable (under special circumstances). Much like 2 large crowds of people with 2 different opinions, a truce can be found. An agreement is sometimes made out of necessity. With the Liquid and Solid from the diagram, this truce allows both to be present at the same time. The proportion of solid-to-liquid will vary, however, based on the relative strengths of the two phases that vary with temperature. In this case, as temperature is increased, Liquid becomes stronger and will dominate. Eventually all the solid will be converted into liquid. This process occurs over the full 150 degree celcius melting range.
This is a fairly simple explaination, but hopefully you get the idea. Maybe we can get Krista to tell us what she does. Her work is very interesting. She works with E. Coli, DNA, kidney cells, and chemistry.
posted by Brandon and Krista at 8:50 AM
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