Influence of surfactants on the hydrodynamics of laser alloying of metals

It is shown that the nature of convective motion in a thin layer of a liquid formed by local heating of a metal surface by laser radiation depends not only on the temperature gradients, but also on the presence of trace impurities in the liquid, particularly of surface-active substances (surfactants), which can alter radically the nature of convection. The results are given of an experimental study of a change in the nature of convection as a result of addition of surfactants during melting of metal samples by radiation from industrial cw CO₂ lasers.