 Cobalt @-@ based superalloys consume most of the produced cobalt . The temperature stability of these alloys makes them suitable for turbine blades for gas turbines and jet aircraft engines , though nickel @-@ based single crystal alloys surpass them in performance . Cobalt @-@ based alloys are also corrosion and wear @-@ resistant , making them ( along with titanium ) useful in medical orthopedic implants that do not wear down over time . The development of wear @-@ resistant cobalt alloys started in the first decade of the 20th century with the stellite alloys , containing chromium with varying quantities of tungsten and carbon . Alloys with chromium and tungsten carbides are very hard and wear resistant . Special cobalt @-@ chromium @-@ molybdenum alloys like Vitallium are used for prosthetic parts ( hip and knee replacements ) . Cobalt alloys are also used for dental prosthetics as a useful substitute for nickel , which may be allergenic . Some high speed steels also contain cobalt for increased heat and wear @-@ resistance . The special alloys of aluminium , nickel , cobalt and iron , known as Alnico , and of samarium and cobalt ( samarium @-@ cobalt magnet ) are used in permanent magnets . It is also alloyed with 95 % platinum for jewelry , yielding an alloy suitable for fine casting and is also slightly magnetic . 
