Investigations of dislocation mechanisms in Ni 3 Al at different temperatures: in situ straining experiments in a transmission electron microscope

The glide of dislocations in the octahedral planes of Ni3Al is studied in situ between 165 and 1123K. Different microscopic behaviours are observed in the low- and high-temperature ranges of the yield stress anomaly domain, and at temperatures above the peak. Local stress measurements and respective intensities of glide in cube and octahedral planes are consistent with results of other techniques. Experimental results in the temperature range of yield stress anomaly are interpreted in terms of double-cross-slip processes between octahedral and cube planes, and octahedral glide at temperatures above the peak in stress involves diffusion processes.