Title: Effects of transmutation elements in tungsten as a plasma facing material,
Abstract: Tungsten (W) is widely considered as the most promising plasma facing
material, which is used in nuclear fusion devices. During the operation of the
nuclear fusion devices, transmutation elements, such as Re, Os, and Ta, are
generated in W due to the transmutation reaction under fusion neutron
irradiation. In this paper, we investigated the effects of the transmutation
elements on the mechanical properties of W and the behavior of hydrogen/helium
(H/He) atom in W by using the rst principles calculation method. The results
are that the generation of the transmutation elements can enhance the ductility
of W without considering the dislocation and other defects, and this phenomenon
is called as solution toughen. However, there is not a strict linear
relationship between the change of the mechanical properties and the
transmutation elements concentration. Compared with the H/He atom in pure W,
the formation energy of the H/He in W are decreased by the transmutation
elements, but the transmutation elements does not change the most favorable
sites for H/He in W. An attractive interaction exists between the transmutation
elements and H/He in W, while a repulsive interaction exists between Ta and He
in W. The best diffusion path H/He in W is changed due to the interaction
between the transmutation elements and H/He. All of the above results provide
important information for application of W as the plasma facing material in the
nuclear fusion devices.