Aliasing correspondance with respect to DFT
If you do spectral analysis is typically better to use WAY more points then 10 in the time domain
Look at your y axis and make sure your graphs are properly scaled. $f=10$ aliases indeed back to $f=0$. All you see is numerical noise and your y-scale is $10^{-15}$. This would be different if you choose a a different phase, cosine instead of sine.