DISLOCATION TRANSFORMATION AND THE ANOMALIES OF DEFORMATION CHARACTERISTICS IN TIAL .4. OBSERVATION OF BLOCKED DISLOCATIONS

To detect earlier unobservable blocked a/2 <112> superdislocations, a two-stage deformation scheme has been developed, which made it possible to reveal latent transformations of superdislocations into barriers. A comparison is drawn between the blocked configuration observed and theoretical models. A study is given to the influence of nonstoichiometry upon blocking of single dislocations. It was found that the temperature at which blocking of single dislocations starts is lower for the Ti-54Al alloy than for the equiatomic alloy. Activation energies of dislocation transformations responsible for the yield stress peak were estimated from the analysis of experimental data for different orientations. An athermal mechanism of the a <101> superdislocation hindering, which is most efficient for the <001> orientation, is discussed.