I'm not sure if this is what you want, but there is an article which mentions briefly about the solubility of Cr2Se3.
"The solubility of Se in (Cr) was not determined, but it is suggested that it is very small, similar to that of S in (Cr). Based on their measurements of the partial pressure of Se corresponding to the equilibrium between Cr2Se3(II) and Se (liquid), [80Zhe] concluded that the solubility of Cr in liquid Se is small."