wherein the metal is selected from {HEAD ~ the group} consisting of: cobalt, nickel or {TAIL ~ chromium}, and a metal alloy of these metals 
wherein the metal is selected from { HEAD ~ the group } consisting of : cobalt , nickel or { TAIL ~ chromium } , and a metal alloy of these metals
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH