how to add this into own database?

[hxie]

I have this reaction:
xA(g）+ (1-x)B(g) --> C(Ax,B(1-x)) where x and 1-x are subscripts

for example,
Si+ Ge--> SixGe(1-x)

what I need to do is to add SixGe(1-x) into my own database so I can use it in my equilibrium.
A and B are not necessarily Si and Ge.
I have define most thermal data for this AxB(1-x) compound or alloy.

this has bothered me for a while.
any suggestion will be appreciated!

[Eltee]

If I understand the question, you want to add a variable composition compound to your data base, in your example, Si(x)Ge(1-x). To do that, you'll need thermo data for the compound across the range of compositions. I can see two ways to do this.

1. If the alloy acts more or less as an ideal solution, you can add two compounds representing the end members of the composition, namely Si and Ge, define properties for them that match your alloy data, then in the equilibrium calculation module, put these two in a separate phase containing these two compounds. If this (condensed) phase is the only one present, make sure that the box "Pure Substances in the Last Phase (Invariant Phases)" is NOT checked so that the compounds will be treated as a solution/alloy, not as a collection of pure substances.

2. If the solution is non-ideal you may need to create a series of compounds across the composition span such that the thermo properties approximate the values you have for the alloy. Then create a series of phases that have adjacent members of these compositions (e.g., Si, Si0.75Ge0.25, Si0.5Ge0.5, etc). Any problem should drop simply by mass balance into one of these "bins", though you might have trouble if your problem has exactly the ratio of one of the members.

I've tried in the past to incorporate non-ideal solution values into HSC problems, but without success. I should say I didn't try very hard, having access to other tools I was more familiar with for those problems.

Good luck