The high temperature peak of the yield strength of γ′-strengthened superalloys

The yield strength and the critical resolved shear stress of many γ′-strengthened nickel-base superalloys exhibit an anomalous temperature dependence: they peak at about 1000 K. Since this peak occurs at the highest temperatures at which these materials are used, it is of great technical importance. A frequently referred to interpretation of the peak is that it is governed by the anomalies of the strength of single-phase L12-long range ordered γ′-intermetallics. In this paper it is, however, shown that there are at least five alternative dislocation mechanisms, which may bring about the peak of the strength of superalloys. These mechanisms are described and their potentials discussed.