We investigated the process of laser heat treatment of polished brass samples (36% zinc, containing a small amount of lead, which does not dissolve in the alloy and is in the form of inclusions, having micron and submicron size) by impacting to a series of 25 - 30 ultraviolet (UV) pulses of a Nd:YAG laser (third harmonic, wavelength λ = 355 nm, duration τ = 10 ns, pulse repetition rate f = 10 Hz, pulse energy density ~ 0.15 - 1.0 J/cm2) in the stationary spot mode. Copper and its alloys absorb up to 90% of the energy of this laser. It is found that the relaxation of the absorbed energy of laser radiation in the metal occurs nonuniformly. Defects in the metal structure such as grain boundaries and lead inclusions are visualized. Traces of crystallographic sliding appear inside some grains. With an increase in the number of impacting impulses, accumulation of damage is observed. A further increase in the radiation energy density leads to an aggravation of the observed phenomena.
The effect of ultraviolet lasers on conversion of methane into higher hydrocarbons
