Mechanical properties and phase transition of tungsten with edge dislocation under intensively-electronic excitation

Under intensive irradiation of ultrafast laser and swift ions, a metal material like tungsten is not in electronic ground state but in excited states. In the excited states, the properties of system intriguingly evolve with the degree of excitation. Revealing how its properties change with the degree of excitation and uncovering the physical nature in the change of properties are of great importance for application of the metal materials in some extreme environment. In this work, through performing tight-binding calculations on the electronically-excited tungsten containing edge dislocation , we found that as the electronic excitation of the system becomes heavier, its bulk modulus, shear modulus, and Young`s modulus become worse, and its ductility gets better first and then turns to be worse. We proposed that this behavior is originated from the bond strength weakened by the electronically-excited states between atoms. Furthermore, it is found that during the evolution of these elastic properties, a solid-solid phase transition in the system happens at the electronically-excited state with electronic excitation energy of around 1.21 eV. We revealed that such a structural phase transition is driven essentially by exciting two soft phonon modes.