Imperfect dislocations at non-basal plane defects in 18R and 2H martensites: Transmission electron microscopy studies

Abstract

Abstract A detailed study of the non-basal plane (NBP) faults in 18R and 2H martensites in Cu—Zn—Al alloys has been performed, using transmission electron microscopy and high-resolution transmission electron microscopy. Four types of NBP fault are possible in the 18R martensite. This set reduces to Fo and Fx after convenient atomic relaxations, producing six types of imperfect dislocation depending on the type of basal plane fault finishing at the NBP fault. The Burgers vectors of all these dislocations have been determined from the analysis of the images. On the other hand, the displacement vectors due to the atomic relaxation along the F1 and F2-type faults in the 2H structure have been carefully determined from the analysis of the dislocations formed at the intersection of the NBP and the basal plane stacking faults. All the relaxations are consistent with the conservation of the volume per atom at the NBP faults. Both NBP faults reduce themselves to the same kind of fault with different dislocations at their ends.