Effective thermal conductivity of alloy

Hi all,

I am trying to model a thermal crystal made up of Si-Ge alloy and airholes in comsol 5.4, for which i am using linear elastic materials in solid mechanics module. I have already modeled the band structure of unit cell by applying floquet boundary conditions and eigen solver analysis. Now i want to find effective thermal conductivity v/s eigen frequency graph of alloy used in same geometry. As COMSOL solves the heat equation in each part of the geometry using its own thermal properties. How can i extract the effective properties?

Thanks in advance