It is often said that the mechanical properties of metals are mostly due to their free electrons. I'm talking about malleability, ductility and hardness. So, when they suffer a superconductive transition, I expect a drastic change in their mechanical properties, but I haven't found anything on the Internet about such consequences. My questions are: What can we expect, regarding the mechanical properties of metals, when they pass from a non superconducting state to a superconducting state? What about type II superconductors?