Troostite

An obsolete term, formerly used to describe the structure obtained when martensite is lightly tempered.

At the time the term was created, this structure was thought to be a distinct phase. The structure is now known to be cementite precipitated in ferrite, however, the precipitate is so fine that it can not be seen clearly using an optical microscope.

Troostite was named after the French chemist Louis J. Troost.