Cobalt alloys are used where resistance to heat and oxidation is a big factor like in the aircraft and aerospace industries.

If you watched the video on your left , you noticed the hot section of the engine colored red. It runs red hot and it takes a special alloy to withstand that kind of heat and stress from pressure and vibration.

Cobalt alloys usually contain some combination of cobalt, nickel, chromium, and tungsten. And are very heat and abrasive resistant.