Laser treatment for samples of copper, its alloys and gold was carried out with a UV pulse of nanosecond duration. After irradiation at subthreshold values of the energy density (E ∼ 0.2 - 0.8 J/cm2) the noticeable changes in the surface layer were revealed. These are traces of thermoplastic deformation resulting from laser exposure. They appear as uneven rise of the irradiated sample surface area up to 1 μm. The effect is cumulative, because the height of the uplifts increases with increasing number of impact pulses. In addition, the characteristic features of high-temperature plastic deformation were observed in the form of crystallographic slip and grain-boundary slippage. At E ∼ 1 J/cm2 or more the optical breakdown occurred with the formation of a crater on the metal surface, that precludes the detection of described effects. The mechanical impulse of a laser plasma, when exposed to a metal surface, prevents the thermomechanical expansion of the material, and therefore, similar effects have not been previously observed. On the surface of materials with a significantly larger elastic limit (single crystals of germanium and silicon, a tungsten carbide) this phenomenon was not observed, because the generated thermomechanical stresses were insufficient to create conditions of plastic deformation.

Институт электрофизики и электроэнергетики РАН, Дворцовая наб. 18, 191186 Санкт-Петербург Теоретически и экспериментально продемонстрирована возможность формирования нанорельефа на поверхности титана методом прямого лазерного наноструктурирования. С помощью атомно-силовой микроскопии определе-ны характерные формы и размеры поверхностных наноструктур. Предложена теоретическая модель и произведена оценка характерных параметров наноструктур на поверхности титана. It is demonstrated the possibility of nanorelief forming on the titan surface by direct laser nanostructuring in theorethical and experimental ways. There were measured characteristic forms and sizes of titan surface nanostructures by means of atomic force microscopy. It is suggested the theoretical model for calculation of characteristic parameters of titan surface nanostructures.

The effect of UV laser pulses of nanosecond duration on surface of Cu-Cr-Zr alloy samples was investigated. Noticeable changes in the morphology of the surface layer after irradiation were found at pre-threshold values of the energy density of ∼ 0.2 – 0.8 J/cm2. Changes are traces of thermoplastic deformation resulting from influence of a concentrated energy flow and appears in irregular elevation of the irradiated surface area of the sample by up to 1 μm and in some cases – more. A developed metal surface, deformation of the crystal structure of the surface layer can support the diffusion process during diffusion welding. For energy densities of the order of 1 J/cm2 or more, optical breakdown with the formation of a crater on the metal surface occurred. The mechanical impulse of a laser plasma when exposed to a metal surface prevents the thermomechanical expansion of the material, and the effect of raising the surface of the samples was not observed.

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