the samples tested were measured at 750 u00b0 f it is well known that rene 39 95 is one of the strongest commercially available superalloys which is known from fig6 it is evident that the ultimate tensile strength measurements made on the respective samples of the hk101 ss alloy and the rene 39 95 ss alloy demonstrated that the hk101 ss alloy indeed has ultimate tensile strength essentially equivalent to the rene 39 95 ss material turning now to fig7 and 8 there is plotted the relationship between the yield strength and ultimate tensile at 1400 u00b0 f versus the cooling rate in u00b0 f per minute for two alloys one being rene 39 95 ss and the other being hk101 ss both of which samples were tested at 1400 u00b0 f the hk101 ss is essentially equivalent to the rene 39 95 ss the data plotted in fig5 7 and 8 demonstrate additionally on a comparative bases that the alloy of this invention has a set of tensile strength properties which are very much the same as the properties of rene 39 95 moreover with respect to inhibition of fatigue crack propagation the subject alloys are far superior to rene 39 95 particularly those alloys prepared at cooling rates of 100 u00b0 f min to 600 u00b0 f min which are the rates which are to be used for industrial production of the subject alloy what is remarkable about the achievement of the present invention is the striking improvement which has been made in fatigue crack propagation resistance with a relatively small change in ingredients of the hk101 alloy as compared to those of the rene 39 95 alloy to illustrate the small change in alloy compositions the ingredients of both the rene.