Ceramasteel

Ceramasteel was a hard metal compound that was used to build an underwater base on the planet Zeta 0-9. Although able to withstand the pressures of deep water, it was unable to stand up to a barrage of a few concussion missiles, which compromised the structure of the base, causing it to explode.

Behind the scenes
This alloy seems to be a portmanteau of ceramics and steel, perhaps describing its nature.