Bilayers and codeposited alloys of Cr and Ta on Si were studied using Rutherford backscattering and glancing angle x-ray diffraction as a function of thermal annealing up to 800 °C. The bilayers produce layered structures of TaSi2 and CrSi2. Phase separation was observed for the alloy CrxTa1−x layers on Si. The interaction produced CrSi2 next to the Si and an outer layer containing a mixture of CrSi2 and TaSi2. No ternary phase formation was detected for anneals up to 800 °C.