Plotting Phase Diagrams (Temperature vs Composition)

[nyxynyx]

I'm planning to plot phase diagrams of Temperature vs Composition. I found the formula $$ln(x) = \frac{\Delta H}{R} (\frac{1}{T_A} - \frac{1}{T})$$ from the Clapeyron equation.

Its a ideal solution of 2 metals in L state and regular solution in S state. Eutectic temperature is at 850C and enthalpy of fusion is \Delta H = 2500 cal/mol (which I converted to 10460 joules) with heat capacity constant, and both materials melt at $$T_A$$ = 1000C. Rearranging to make T the subject got me T = \frac{1}{\frac{1}{T_A} - \frac{R ln(X_A)}{\delta H}

$$T = \frac{1}{\frac{1}{T_A} - \frac{R ln(X_A)}{\delta H}$$

However the graph that I get when plotted out in Matlab does not look like a eutectic graph. I plotted 1-X and X for both metals, and T=1150 for the eutectic line but they don't seem to match. The eutectic point is way lower than the eutecetic line. Did I do something wrong? Thanks!

http://img340.imageshack.us/img340/5455/54676710.jpg

 

[Mapes]

The Clapeyron equation relies on some simplifying assumptions, one of which is that the solid state is absolutely pure. I wouldn't expect it to be perfectly reliable far away from $x_B=0$ or 1.

 

[nyxynyx]

Is there a better equation to use to plot out the binary eutectic phase diagram?

 

[nyxynyx]

Im still unable to figure this out... need a little help thanks :)

 

[sardar]

I would suggest checking your calculations and equations again to ensure accuracy. It is possible that a small error in your calculations could lead to a significant difference in the resulting phase diagram. Additionally, I would recommend using multiple sources and references to cross-check your findings and equations.

Furthermore, it is important to consider the assumptions and limitations of the Clapeyron equation and the ideal solution model you are using. In reality, there may be other factors at play that could affect the phase diagram, such as non-ideal behavior and interactions between the two metals.

I would also suggest considering using a different software or program to plot the phase diagram, as it is possible that the issue could be with the plotting software rather than your calculations.

Overall, it is important to carefully review and double-check your work and to consider any potential limitations or sources of error when interpreting the results.