cobalt chromium molybdenum is used in a variety of applications that require high corrosion resistance. It is also an excellent material for applications that require high strength. These alloys are extremely hard and have a yield strength of up to 500 MPa.
Typical metallurgical parameters for cobalt-chromium alloys include: from 26 percent to 31 percent chromium, from 4 percent to 6.5 percent molybdenum, up to 1 percent each of silicon, manganese and iron, and from 0.3 percent to 0.5 percent carbon. These alloys may be further differentiated by addition of copper, aluminium, titanium, niobium, vanadium, zirconium, tantalum and boron, both individually and in combinations.
The chromium content in cobalt-chromium alloys determines their solubility limits and how easily they can be formed into solid solutions. If the chromium content is below about 30%, the metal is soluble in liquid solution.
However, once the chromium content is over about 30%, it is no longer soluble in liquid and begins to form into a sigma phase. The sigma phase imprints the chromium content onto the material, resulting in increased corrosion resistance.
Cobalt-chromium alloys are used in a variety of medical applications, including orthopedic implants. These alloys have superior tensile and compression properties, and are biocompatible. They are also resistant to corrosive environments and extreme temperatures. They are used in hip and knee replacement devices, for example.