Well while we are naming exotic hard to machine metals…
FW3ST - Stellite
FW3CA - Carbide
FW3TU - Tungsten
FW3CR - Chromium
FW3CE - Ceramic
FW3CO - Cobalt
All are quite fun to machine. I do get to machine some pretty exotic materials and its always a fun learning experience.
And for the more sci-fi folks we have the
FW3DM - Dark Matter
You have to keep it in a vacuum suspension chamber next to your Uranium and Plutonium models underneath your volcano evil lair.
Yeah we use it for reactor plant valve seals and some turbine parts. I got to do some work with sintered parts as well a while back and we made some stuff from sintered Tungsten and ceramic with Molybenemum. Surface finish requirements were sub 20 RA using a Mitsubishi wire EDM and a tolerance of -+ 0.0001. What a flashlight that would make huh?
And now for something completely different….
There are 2 materials that are not the most practical out there but one is practical enough to have a niche and the other - I don’t know but maybe.
1. Beryllium copper. High conductivity CuBe has good thermal properties and is much tougher than pure copper. Machining requires seriously good ventilation though.
2. Magnesium. Thermally - ok to good. Mechanically - passable. Weight - superb. Price - high but way lower than some exotics. Corrosion is a problem. Is it a blocker that can’t be resolved well enough for a reasonable price? I don’t know.