The effect of treatment with a low-energy high-current electron beam with an electron beam energy density of 30 J/cm and a pulse duration of 50 microseconds on the formation of the surface relief of molybdenum high-speed steel previously subjected to high-temperature tempering has been studied. Scanning electron microscopy revealed that the surface relief is represented by craters ranging in size from 5 to 250 microns. The average size of the craters is 91.3 ± 63.1 microns, and the most probable size is in the range from 40 to 50 microns. A comparative analysis of the mechanisms of crater formation is carried out based on the concepts of the development of Rayleigh—Taylor, Richtmayer—Meshkov instabilities and thermocapillary instability at the interface of melt and plasma. It is shown that if these instabilities are considered separately, they do not provide an adequate explanation for the formation of craters in this size range. The analysis of the initial stage of combined thermo-, concentration-capillary instability and Rayleigh—Taylor, taking into account the vapor recoil pressure, allowed us to establish a three-mode dependence of the growth rate of disturbances at the interface of the melt and plasma on the wavelength. The first maximum is due to the concentration gradient, which falls at a wavelength of 4.4 microns. The other two maxima occur at wavelengths of 12.7 and 191.8 microns, respectively, and are caused by a temperature gradient, melt acceleration, and vapor release pressure.
Nevsky et al. (Wed,) studied this question.