Grain boundary populations in wet and dry NaCl

Abstract

The presence of water causes significant weakening of polycrystalline NaCl because fluid assisted recrystallisation and diffusion creep occurs along grain boundaries. In metals and ceramics, special low energy boundaries are often not wetted by fluids and this affects properties. The aim of the present paper is to use EBSD to determine whether special boundaries exist in NaCl and whether these are wetted. Wet and dry polycrystalline NaCl were examined, deformed by dislocation creep and statically and dynamically recrystallised. Coincident site lattice (CSL) boundaries in recovered material occurred with frequencies expected from the texture, whereas boundary populations of recrystallised material were significantly different from those expected from the texture, and may have been influenced by special boundaries, approximately parallel to {100} planes. Coincident site lattice boundaries became discontinuous with increasing strain in dry NaCl because of subgrain rotation. Both CSL and special boundaries migrated like general boundaries at low temperatures and are therefore likely to have been wetted.