Effects of tantalum alloying on surface morphology and deuterium retention in tungsten exposed to deuterium plasma

Tungsten and tungsten-tantalum alloy with tantalum concentration of 10 wt%, sintered by spark plasma sintering, were exposed to deuterium plasma at ∼500 K with flux of 1 × 10²¹–1 × 10²² D m⁻²s⁻¹, an ion energy of 40 eV and fluence of 1 × 10²⁵–1 × 10²⁶ D m⁻². After exposure, a large number of blisters with an average size of 1–2 μm form on the surface of tungsten, and the area density of blisters increases with increasing irradiation fluence. However, the dominant morphology on the surface of tungsten-tantalum alloy is characterized by the striped microstructure, and exhibits a strong grain-orientation dependence. TDS results show two major desorption peaks located at ∼650 K and ∼770 K for tungsten and tungsten-tantalum alloy, respectively. Furthermore, the deuterium retention in tungsten is 4–6 times more than that in the tungsten-tantalum alloy. It is suggested that tantalum alloying can be expected to suppress the surface blistering and reduce the deuterium retention in tungsten.