The present paper describes a new approach developed in order to determine the Coefficients of Thermal Expansion (CTE) of phases embedded in two-phase materials. The procedure is based on the coupling of numerical simulations with scale transition models and experiments. A three scales one-site thermo-elastic self-consistent model following the formalism introduced by Kroner and Eshelby (KE) was extended to multiphase materials. Preliminary numerical computations justify to identify the CTE of a given phase embedded in a two-phase material with the CTE of the corresponding pure single-phase. This additional assumption was introduced in KE model. The implementation yields an explicit formulation for the unknown CTE of a phase embedded in a (alpha+beta) two-phases material. The application of this expression to the characterization of beta thermal expansion properties implies the measurement or knowledge of several parameters. This approach was checked through the study of an Al-50%vol.-SiC-50%vol. MMC. The CTE of Silicon Carbide were determined as a function of the temperature. Simulated results obtained show a very good agreement with experimental values available in the literature.