Temperature dependence of dislocation microstructure in Ni3(Al,Hf)

Transmission electron microscopy observations were performed on Ni74.8Al21.9Hf3.3 specimens deformed at different temperatures (room temperature to 983 K). The dissociation width of superdislocations has been examined as a function of the deformation temperature in these samples. Evolution of the dissociation width was also investigated during in-situ heating experiment up to 1000 K. The temperature dependence of the antiphase boundary energy (γAPB) was deduced from these observations. The importance of taking into account the temperature dependence of elastic constants is highlighted and it is shown that γAPB decreases with increasing temperature.