The alloy on the oxygen side pump in the Raptor engine is a work of magic and or art. An oxygen rich turbopump runs so hot it was thought impossible to create because the turbine would fail before the burn was over. SpaceX had to invent the alloy before the first Raptor full duration fire. That's a very low level, never done before, breakthrough required just to get to the real hard stuff.

edit: if you watch gas generator tests on youtube the gas coming out is dark because it's very fuel rich which keeps it cool (in a relative sense)