Determination of active deformation mechanisms in a NbTaTiV high entropy alloy

In this paper, the results of a study of the active mechanisms of plastic deformation in the high entropy alloy NbTaTiV are presented. Thus, following heat-treatment of a sample of this polycrystalline bcc alloy, coupons have been deformed in compression at room temperature and the active deformation mechanisms have been characterized using transmission electron microscopy (TEM). It has been observed that plastic deformation is principally accomplished by dislocation glide. Using diffraction contrast techniques, it has been determined the dislocations have Burgers vectors given by b = 1 / 2 〈 111 〉 . To identify the actual slip planes activated and the character of the dislocations present, trace analyses based on stereographic techniques have been undertaken. The slip planes have been found to be predominantly {110}, although the observation of possible cross-slip on a {112} plane was observed. Regarding the character of the dislocations, the deformation substructures of NbTaTiV are dominated by dislocations which are essentially screw in character such that it is possible to conclude that the edge segments have greater mobility than screw segments, as is common in other bcc -RHEA’s and, indeed, other bcc -based alloys. As noted in the following, this determination is not in agreement with those presented in a recently published study, and this marked difference in results is discussed.