I have three elements, A, B, C, that under certain conditions (rapid heating and cooling) form one ABC phase solid. Sometimes when I add a fourth element, D, I get two phase (AB,CD) solid. Obviously this phenomena is thermodynamically favourable. My guess (still undergraduate) is that there is a solubility limit in the solid phase of these elements in a way that beyond a certain amount of D, the chemical potential of the ABCD phase is higher than that of two-phase solid. I want to offer a model that will explain this phenomena. Problems are: 1. This is a proccess that occurs in high temperatures and pressure (4000K and 40,000psi in 1 millisecond) so it can't be easily reproduced in the lab. 2. I didn't find any phase diagrams of A-B-C-D and their combinations. 3. Prior research on the subject is almost non existent. I really don't know where to start. This is not homework, it's a research project I'm interested in. I'll appreciate any help/direction.