Tests were performed on CMSX-4 superalloy at temperatures of 1223 or 1023K, and the [001] and [256] orientations were investigated under tensile and compressive loading conditions. It was demonstrated that, in addition to stacking fault generation, twinning of the complete 2-phase structure was a major source of creep strain accumulation under certain conditions. These depended upon the activation of suitable a/3<112>{111} partials which were a function of the sign of the resolved shear stresses. Transmission electron microscopic analysis and EBSD measurements showed that twin nucleation depended upon the activation of suitable <110>{111}-type slip within the matrix channels. However, once it had taken place, deformation could proceed rapidly; being hindered only if a suitable network of dislocations within the matrix channels could be created to halt the progress of the twinning partials.

The Role of <112>{111} Slip in the Asymmetrical Nature of Creep of Single Crystal Superalloy CMSX-4. D.M.Knowles, S.Gunturi: Materials Science and Engineering A, 2002, 328[1-2], 223-37