Crater generation and mass transfer at irradiating by heavy-current impulse electron beams

Full text: Radiation processing by bunches of charged particles gains usage in the technology of the final processing of metal articles. One of the perspective methods of exploitation property improvement is irradiating by heavy-current impulse electron bunch of microsecond duration. At such processing surface structures, properties of which sufficiently change, are formed. Mass transfer and crater generation usually influence on the properties of the surface. The researches of the generated craters and changes of elemental composition at irradiating are important not only for managing of the technological process at materials ray processing, but they are also of scientific interest. Crater generation and mass transfer at irradiating of HIEB was researched on the metal samples of various values of thickness and composition. Diameter of the samples was chosen as significantly less that thickness, area of sample surface was also chosen as significantly less than bunch area. Irradiation was conducted by impulse electron bunch with energy E∼500 keV in impulse and impulse duration t∼2.5 μs, bunch current density j∼1.4 kA/cm2. The researches of the samples of metal titanium and copper, alloys WT and 12H18N10T were performed. Before irradiating the samples were mechanically ground, and then they were buffed according to the standard method. After being irradiated the samples had been etched in 10% solution of oxalic acid for several minutes. Irradiated surfaces were researched on the optical microscope (MIM-8) and scanning microscope with add-on device microanalysis JEOL-5610. The elemental analysis was performed along the crater surface. Irradiating of HIEB leads to generation of the craters with changing of elemental composition on crater surface. It was experimentally determined that for the irradiated materials, the cause of crater generation, is pinching or filamentation of the bunch. Hence, the calculation of temperature field and stress field in the crater was performed. The model of radiation-stimulated mass transfer, taking into account concentration, thermal, vacancy mechanism and barodiffusion was developed for for explanation of mass transfer in the crater. The calculation of element redistribution in the crater was performed. The results of the calculations agree with the experimental data