Phase transformation research of fusion reactor first wall material tungsten

Tungsten is remarkable for its robustness; especially it has the highest melting point of all the non-alloyed metals. Tungsten and tungsten alloys have been widely used in aerospace, weapon, nuclear industries and fusion reactor. Tungsten is expected to become fusion reactor first wall material for this reason. In this paper, phase transformation processes of fusion reactor first wall material tungsten have been investigated via molecular dynamics simulation based on the modified embedded atom model. Surface melting velocities at different temperatures are calculated as V(T) = −5.082 + 0.00136T and thermodynamic melting point is determined by fitting front advance velocities. Structure changes, thermal expansion coefficient, radial distribution function, static structure factor and average atomic energy for uniform melting processes are studied to simulate plasma thermal shock heating to superheat state of tungsten in fusion reactor. The superheat limit of tungsten crystals can be gotten according to simulation results. The superheat limit for tungsten crystal melting is about 27.2%. Tungsten is the best plasma-facing material because of its highest melt point and highest limiting superheating of all the non-alloyed metals. -- Highlights: • Surface melting velocities and melting point are gotten in surface melting process. • Uniform melting processes are analyzed using RDF, SSF and average atomic energy. • The highest limiting superheat shows tungsten is the best plasma-facing material. • New material combinations will be required based on the tungsten in fusion reactor