“The cobalt based superalloys consume most of the produced cobalt. The temperature stability of these alloys make them suitable for turbine blades within gas turbines and jet aircraft engines. The nickel-based single crystal alloys surpass the cobalt based in temperature stability, but the cobalt based are still in use. These alloys are also corrosion and wear-resistant.[13] Special cobalt chromium molybdenum alloys are used for prosthetic parts such as hip and knee replacements.[14] Some high speed steels also use cobalt to increase heat and wear-resistance. The special alloys of aluminium, nickel and cobalt, known as Alnico, and of samarium and cobalt (samarium-cobalt magnet) are used in permanent magnets,[15] which can be used for recording media,[16] cemented carbides (also called hard metals), and diamond tools.”

If you’re interested, here’s a cobalt steel kitchen knife:

https://www.arizonacustomknives.com/products/?id=5746