TiO2 nanoparticles have very wide and interesting applications. Therefore, you can make many composites using TiO2 NPs and it depends on your field of interest. I suggest that you do a quick search to find out the various applications of TiO2 NPs and thier composites.
TiO2 are suitable with quite wide spectrum of metallic and intermetallide matrices, for example: iron-based alloys (including highly alloyed tool steels), nickel superalloys, titanium-aluminides, etc. Of course, in any special case, interaction/stability of titanium oxide particulate reinforcing should be taken into account.