A series of nickel-base superalloys with gamma' fractions changed from 0 to 100 mol% and with gamma and gamma' compositions kept constant were designed and examined in terms of high temperature tensile properties. In the temperature range from 900 to 1000 degrees C, 0.2% proof stress shows a maximum at about 85 mol% in a corrected amount of gamma', whereas at 1100 degrees C, it shows maximum at about 65 mol%. The maximum shift of proof stress from the law of mixture in strength was constant for these temperatures. In the strain rate range from 10(-8) to 10(-2)/s at 1000 degrees C, the maximum shift of proof stress increased with the strain rate. The proportion of the shift stress to the proof stress becomes larger as the temperature increases. (C) 1997 Elsevier Science S.A.
