Subsurface morphology changes due to deuterium bombardment of tungsten

Abstract

Re-crystallized polycrystalline tungsten was exposed to a deuterium plasma beam

Temperature dependence of surface topography and deuterium retention in tungsten exposed to low-energy, high-flux D plasma

“…On the contrary, at lower temperatures they lead to strongly stressed regions (hundreds of cubic microns) and cracks at grain boundaries and inside the crystallites. The surface blister-like structures and the defects underneath are correlated along crystallographic orientations of the W grains in accordance to the low-indexed sliding systems [12].…”

Surface morphology and deuterium retention in tungsten and tungsten–rhenium alloy exposed to low-energy, high flux D plasma

“…As already noted, for tungsten exposed to low-energy, high flux hydrogen plasmas, plastic deformation caused by hydrogen atom supersaturation [8] is considered to generate defects responsible for accumulation of the implanted hydrogen [10]. During exposure to the high flux hydrogen plasma, a high hydrogen concentration in the implantation zone stresses the matrix lattice.…”

“…During exposure to the high flux hydrogen plasma, a high hydrogen concentration in the implantation zone stresses the matrix lattice. When the compressive stress induced by the hydrogen supersaturation exceeds the yield stress of the material, fracture deformation and/or plastic deformation occur [8], and both intergranular/intragranular cracks (cavities) [10] and vacancy-type defects (vacancies and vacancy clusters) [20] are generated. Diffusing hydrogen atoms are trapped at the 6 vacancy-type defects forming consequently gas bubble nuclei, and recombine also on the cavity surfaces.…”

“…As illustrated for the example of recrystallized W exposed to low-energy, high flux D plasma [10], at exposure temperatures above the BDT temperature the dislocation mobility is increased and the stress can be relaxed by dislocations moving along lattice planes through the whole crystallite leading to formation of cavities at the grain boundaries at depths of several tens of micrometers. This corresponds to the material migration above the surface, i.e., the blister-like surface topography.…”

“…For W materials exposed to low-energy, high flux hydrogen plasmas, local plastic deformation caused by hydrogen super-saturation within the nearsurface layer [8] is suggested as a mechanism for formation of intergranular and intragranular cracks, and, at long-term plasma exposure, for gas-filled void formation at depths up to several micrometers and, as consequence, for blistering [9][10][11]. It is known that an addition of Re not only improves the low temperature ductility of the tungsten material, but also increases 1 The term 'low-energy ions' means that the ion energy is below the displacement threshold.…”