Regrading the question, in the case of small specimens made through SPS process, you can use compression test, 3-points bending test, Micro-Hardness as well as small-Tensile tests and Nano-indentation.
For the mentioned tests you should have a look at the following links:
Article Formation mechanism of nano titanium carbide on multi-walled...
Article Pulsed current field assisted surface modification of carbon...
Article The effect of TiC:CNT mixing ratio and CNT content on the me...
As mentioned, for investigating contribution of each reinforcement, micro structural characterization near each interface must be examined. It can reveal about bonding of each contributing reinforcement and can be concluded to the strength provided by separate reinforcement according to bonding achieved and observed through in depth micro-structural analysis.
In the same field we can also do scratch test to see the surface morphology and reinforcing behavior according to the scratch trend near interface areas.