Bulk Texture and Structure Changes in Tubes of Zr Alloys due to the Long-Range Effect of Ion-Plasma Surface Treatment

Abstract

Irradiation of metal materials with low-energy ions is accompanied by the long-range effect, consisting in distinct texture and structure changes at the depth, exceeding, at least, by 104 times the thickness of the layer of ion retardation. In order to ascertain mechanisms of this effect, a layer-by-layer X-ray study was carried out as applied to ion-plasma treated cladding tubes of Zr- 1%Nb alloy for nuclear reactors. Impacts of pulse treatments with helium plasma by two different regimes and the ion energy of ~ 1 keV were compared. It was found, that only by minimal surface melting the ion-plasma treatment causes unpredictable bulk texture changes, consisting in arising of the axial texture component. The melted surface layer suppresses shock waves, associated with braking of ions and supposedly responsible for stimulation of dislocation processes at long distances from the surface.