5 in 4 reduction of area when breaking z in alloys 1 and 2 correspond to those in accordance with published german patent application de 22 25 577 c2 alloys 3 and 4 are reference alloys outside of the range for the present invention alloys 5 and 6 have a composition in accordance with the invention alloys 1 and 2 which are cited for comparison and which correspond in their composition to the claims of de 22 25 577 c2 achieve relatively favorable values of strength and rupture deformation however as already mentioned a further increase of the mechanical properties is not possible for this alloy base the alloys with an addition of tantalum do not result in every instance in the desired improvements of properties as demonstrated by the values of reference alloys 3 and 4 which are not in accordance with the invention only the coordination of the molybdenum and tantalum contents in accordance with the invention in alloys 5 and 6 yields noticeably favorable values for the 0 2 permanent elongation limit to above 60 n mm 2 and elongation at rupture values of 8 and higher current density potential curves were recorded in artificial saliva according to fusayama with and without slot using known cobalt alloys and cobalt alloys in accordance with the invention in order to test corrosion resistance the breakdown potential served as the criterion for the corrosion resistance and in the case of the specimens with slot plastic ring put on the repassivation potential as well the measured values are given in the following table 2 table 2__________________________________________________________________________alloy a b no c cr mo ta n other a b b __________________________________________________________________________1 0 2 29 4 93 0 26 si.