Modification of the constructional materials with the intensive charged particle beams and plasma flows

The analysis of the experimental and theoretical work state-of-the-art in the field of the constructional materials modification with the intensive flows of charged particles and plasma with the power density ranging in interval 0.1-1000 MWt/cm2 is carried out. The irradiation modes with the inherent physical processes and the role of different mechanisms in formation of the properties of treated materials are surveyed. The irradiation can be divided onto two modes: subcritical and supercritical. In the subcritical irradiation mode a target material remains in the solid state or melts. In the supercritical regime the formation of plasma torch and its subsequent expansion at a rate of more than 103 m/s are observed. The transition from subcritical to supercritical mode has a threshold character. The mechanisms of mechanical stresses formation under irradiation are discussed, these stresses are the shock wave propagating with a sound velocity and the localized near the irradiated surface stresses arising due to the nonhomogeneous space distribution of the temperature in target material. The reasons of target surface smoothing and of crater formation are given. It is shown that the manifestation of one or another phenomenon of irradiation is determined by its mode. The analysis of mass transfer occurring due to diffusion, thermocapillary convection or development of Richtmyer-Meshkov instability is carried out in accordance with the irradiation mode. The irradiation of the solids leads to the deformation hardening mainly at the expense of shear component of the localized stresses. The decrease of the irradiation duration provokes the high strain rate and the high level of shear stresses that both provide more effective generation of dislocations.