The effect of thin titanium carbide layer on the ion beam mixing of Ni and Si was studied. No mixing was observed following the ion beam bombardment at 600 keV to the fluence of 8×1015Xe++/cm2. Furthermore, it was also found that Ti and C layers alone could prevent an ion beam mixing between Ni and Si, although in the Ti case mixing did occur between Ti and Ni. These results were compared to a thermodynamic model of ion mixing and found to be in qualitative agreement but relative quantitative agreement was poor.