Creep strengths of a Ni-base single crystal superalloy TMS-82+and its tie-line alloys

The gamma' fraction dependence of the creep properties of the second generation single crystal (SC) Ni-base superalloy, TMS-82 +, and their gamma/gamma' tie-line alloys is presented. The gamma' fraction is varied between 0 and 100%. The gamma and gamma' phases of the alloys are designed to have the same chemical composition so that gamma' fraction dependence can be assessed independently. The gamma single-phase alloy is weaker than the gamma' single-phase alloy. The best creep property is obtained with the gamma' fraction between 60 and 70%, depending on the creep condition. The optimum gamma' fraction decreases at higher temperature and lower stress. The SC alloys show larger gamma' fraction dependence compared with the conventionally cast polycrystalline alloys previously reported.