Modification of the Cu-Zr bronze surface by exposure to powerful UV laser pulses

Abstract

The laser pre-treatment of Cu-Zr alloy surface for diffusion welding, which is used in the aerospace industry for joining dissimilar materials, has been investigated. The effect of a nanosecond UV laser pulse on the surface of Cu-Zr alloy samples was studied. It was found that at a pulse energy density E ∼ 0.2-1 J/cm2 pre-ablative microscopic effects of mainly thermal nature were observed in the metal, also there were uplifts of material in the irradiated zone. The surface profile of the sample in the irradiated zone corresponds to the energy distribution of the laser beam. Significant deformations occurred in the crystal structure of the surface layer, and an irreversible configuration of the metal surface was created. At E ≥ 1 J/cm2 an optical breakdown with the formation of a plasma torch and with the appearance of a classical laser crater was observed. The arising erosion of the surface prevented registration of this effect. Microanalysis showed that the concentration of zirconium in the surface layer of the metal after exposure decreased.