MODELING HIGH-TEMPERATURE CREEP OF ANISOTROPIC MATERIAL

Cast single-crystal superalloys are being used as turbine blades in mo dern aeroengines with [001] axis oriented along the direction of princ ipal stress. This allows use of higher operating temperature with asso ciated improvement in efficiency. Although [001] is the natural direct ion of crystal growth in these alloys it is often not possible to atta in perfect alignment. Consequently, besides time-dependent deformation this would induce a change in cross-sectional shape and crystal orien tation of the blade as a result of service exposure. Therefore in orde r to exploit their full potential it is necessary to develop a predict ive system which could model effect of crystallographic anisotropy on high-temperature creep deformation of such materials. The paper review s the recent developments in this direction and suggests that modellin g not only helps in identifying the dominant mechanisms of deformation but also suggests simple experiments to verify them.