Analysis of high temperature creep in the single crystal nickel-base alloy SRR 99 in <100> orientation

From creep curves of the single crystal nickelbase alloy SRR 99 stress and temperature dependencies of the minimum creep rate are calculated in the temperature range 1023 K ≤ T ≤ 1423 K. A stress exponent n=4.7 and temperature dependent threshold stresses were evaluated. The results are discussed in relation to the microstructure. They can be understood by introducing CRSS τGE and τGS, which are due to the incorporation of dislocation segments into interfacial networks at high temperatures resp. to cutting of interfacial networks at lower temperatures. (orig.)