Creep deformation mechanisms in some modern single-crystal superalloys

The creep deformation in some modem superalloys was studied to clarify the creep mechanisms under a high-temperature and low-stress condition and a low-temperature and high-stress condition. At a temperature of 1100 degrees C and a stress of 137 MPa or at a temperature of 1000 degrees C and a stress of 245 MPa, the large gamma/gamma' lattice misfit in negative with the addition of Mo leads to the formation of dense interfacial dislocation networks. These dislocation networks are effective in strengthening the alloys during creep by preventing the penetration of the gamma dislocations into the gamma' phase. At a temperature of 800 degrees C and stresses of 735 MPa and 607 MPa, the improved creep properties of the superalloys are due to the solid solution strengthening by the addition of Ru.