ABSTRACT
At high temperatures, stresses imposed on metal components produce a continuously increasing strain even if they are below the yield point, and result in a phenomenon known as creep. At lower temperatures the creep rate decreases more rapidly with time, in the regime of logarithmic creep. The continuous plastic flow of a material during creep can eventually result in large plastic deformations and significant modifications to the microstructure of the material, and may terminate in fracture by creep rupture. Some of the most important creep-resistant alloys are strong at high temperatures because the cores of their dislocations dissociate by climb into configurations which cannot glide. The addition of solid solution elements and finely dispersed precipitates impedes dislocation motion, and these are further methods of improving creep strength. Probably the most demanding application in which creep resistance is of paramount importance is in the aircraft gas turbine engine. The superalloys are widely used in this field.
