Abstract: Based on the tension/ compression yield behavior of nickel base single phase (r' ) single crystals, the yield behavior of single crystal blade superalloys (made of r' and r phases) has been studied. It is shown that the activation of octahedral slip systems is determined by LCP or PPV models and Schmid law down and up the tip temperature, respectively, and that of cube slip systems can be determined by Schmid law on certain precise degree. The tip temperature which is dependent on crystal orientations is relative to the activation of cube slip systems and the destruction of Kear-Wilsdorf dislocation mechanism. The yield laws and analytical procedures put forward in the paper are confirmed quantitatively by experimental results.

Key words: Single crystal blade superalloy, single phase single crystal superalloy, tension/compression yield behavior, mechanical expressions