Any material can fail, I have seen some aluminum mountain bikes just crack through various places. BMC had a terrible problem with this to the point that my LBS stopped selling them, I am sure there was more to it than just the frames breaking but that was what the head of rentals told me.

The scary thought of having a faulty road bike fork is I often bomb down hills where I get going 40+ mph. I always inspect everything before doing a ride where I know this is a possibility but how many don't?