Cobalt chrome molybdenum alloy

Bolten, J. D., Hayden, J., and Humphreys, M., "A Study of Corrosion Fatigue in Cast Cobalt-Chrome-Molybdenum Alloys, Engineering in Medicine, Vol. 11, 1982, pp. 59-68. 

Metals are utilized for applications requiring high strength and/or endurance, such as structural components of heart valves, endovascular stents, and stent-graft combinations. Commonly used alloys include austenitic stainless steels (SS), cobalt-chrome (Co-Cr) alloys including molybdenum-based alloys, tantalum (Ta), and titanium (Ti) and its alloys. Elgiloy, a cobalt-nickel-chrome-iron... 

Stainless steels contain enough chromium to confer corrosion resistance by passivity. The passive layer is not as robust as in the case of titanium or the cobalt chrome alloys. Only the most corrosion resistant of the stainless steels are suitable for implants. These are the austenitic types — 316,316L, and 317, which contain molybdenum. Even these types of stainless steel are vulnerable to pitting and to crevice corrosion around screws. 

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