Critical temperature of superconducting transition in plastically deformed rhenium single crystals

Abstract

The effect of tensional plastic deformation and of defects produced during this process on the change in temperature (Tc) of the superconducting transition of Re single crystals has been considered. The Tc dependence on the degree of plastic deformation has been obtained for different deformation temperatures and crystal orientations. Electron microscopy show that the defect structure of deformed Re is characterized by the presence of planar defects, i.e. a combination of slip bands and twin layers, between which single dislocations, dislocation arrays, loops, and dipoles are observed. Annealing and quenching experiments on deformed single crystals show that point defects and dislocations have a marked influence on the change in Tc while planar defects have an insignificant effect.

Twin boundary interactions with grain boundaries investigated in pure rhenium

“…Similar to previous studies [1,2], the work here has shown that {1121} twinning is a dominant deformation mode in Re. The dominant grain orientations, with the [0001] oriented perpendicular to the compression direction, would also encourage the observed twinning behavior.…”

“…This extensive twinning is likely responsible for much of rhenium's ductility, as well as a large contributing factor to its high work hardening rate as the twin planes create barriers to further dislocation and twinning-based plasticity. Many of the previous studies of Re have been limited to deformation of single crystals [1,5]. This study has shown the important role of grain boundaries in relation to twin deformation, with high angle grain boundaries providing much stronger barriers to twin propagation than low angle grain boundaries.…”

“…Re is unusual among HCP materials in that the dominant twining system, when either tensile or compressive stresses are imposed on the sample, is the {1121}<1126> [1,2]. It is also unusual among refractory metals in that it has no known ductile to brittle transition.…”

“…However, limited availability and difficulty of extracting Re has limited both the application as well as the knowledge of Re. Characterization of the deformed microstructure of Re has been limited primarily to optical microscopy [3,4] as well as a limited number of transmission electron microscopy (TEM) studies [1,2,5]. These studies reported observations of dislocation plasticity occurring on the basal and prismatic planes, as well as twinning activity on {1012}, {1122}, and {1121}.…”