Based upon an analysis of the dislocation structure, the process of self-blocking, i.e., the transformation of glissile super-dislocations into dislocation barriers without the effect of an external stress, was investigated in the intermetallic compounds with an L12 superstructure. Using different regimes of heating without stress after preliminary deformation both below and above the temperature Tmax corresponding to the peak in the yield-stress temperature dependence, a characteristic feature of self-blocking was revealed in the intermetallic compounds on the basis of Ni3Al, namely, the barriers were formed, but they were not destroyed. This feature was observed not only for single crystals of Ni3(Al,Nb), but also for single crystals of the two-phase complex intermetallic alloy VKNA-4U, which contained 90% γ’ phase. By adjusting the temperature of heating and the duration of heating after preliminary low-temperature deformation, it was possible to observe the initial stages of the process of self-blocking of super-dislocations for single crystals of Ni3(Al,Nb). In experiments on the high-temperature deformation of intermetallic compounds, the process of extension (straightening) of dislocations along a preferred direction was revealed and its thermo-activated nature was proved. Based upon the example of a well ordered alloy Ni3Fe, the possibility of using the experiments with heating of preliminarily deformed intermetallic compounds for rapid analysis of the nature of the anomaly of the temperature dependence of yield stress was demonstrated. In particular, for Ni3Fe the observed anomaly was not connected with the transformations of super-dislocations into barriers.

Some Features of the Formation and Destruction of Dislocation Barriers in Intermetallic Compounds III - Thermoactivated Straightening of Dislocations along a Preferred Direction in Ni3Al. Patselov, A.M., Antonova, O.V., Greenberg, B.A., Ivanov, M.A., Plotnikov, A.V., Vedernikova, I.I.: Physics of Metals and Metallography, 2007, 104[5], 514-21