The formation of C49 and C54 Ti(Si1-yGey)(2) germanosilicide phases in a Si0.65Ge0.35 totally relaxed alloy and in a Si16Ge10 strained layer superlattice (SLS) structures was studied. A Ti layer has been deposited directly on the samples and annealed in the temperature range 600-750 degrees C. The samples have been studied by Auger electron spectroscopy, secondary ion mass spectroscopy, X-ray diffraction, Raman scattering spectroscopy, and atomic force microscopy techniques. It was found that the C49-to-C54 phase transition temperature is higher in the Ti/alloy structure than in the Ti/SLS one. Morphological results show that the average germanosilicide grain size is larger in the superlattice sample than in the alloy sample. This fact is consistent with a C49-to-C54 phase temperature transition higher in the Ti/alloy sample than in the Ti/SLS.