Effect of Structure on Creep Behaviour of Superalloy Single Crystals
Creep behaviour of two types of superalloy single crystals of the orientation <001> was studied at 850 °C in air to assess their relative suitability for turbine blade applications: CMSX-4 and its potential low cost alternative, CM186LC. The chemical composition of these two superalloys is similar, their microstructure, especially g/g’ distribution, differs substantially. At the same applied stress, the time to failure of CM186LC is shorter than that of CMSX-4. Simultaneously, the creep rate of CM186LC is higher than that of CMSX-4 for the whole lifetime. This is attributed to easier activation of dislocation sources within large g’particles present in CM186LC crystals.
P. Lukáš et al., "Effect of Structure on Creep Behaviour of Superalloy Single Crystals", Materials Science Forum, Vol. 482, pp. 267-270, 2005