The results of optical diagnostics of physical processes occurring on the surface of Nickel alloy powder melt in selectivelaser melting (SLM) technology are presented. The independent registration of the dynamics of the brightnesstemperature and the fraction of the laser radiation reflected from the surface of the melt was carried out. Thedependences of the surface temperature of the melt averaged over the time of observation on the specific volumetric heatinput were obtained for the two values of the width of the generated paths. A multiwave method of optical diagnostics isproposed, including monitoring of laser radiation reflected from the melt surface. It is shown that amplitude pulsations ofthe reflected radiation induced by fluctuations of the relief of the melt surface associated with dynamics of the surfacetemperature of the melt: the number of ripples on the waveform of the reflected radiation increases at the stages ofdecline of the brightness temperature. This observed phenomenon shows the relationship between changes in surfacetopography and convective processes in the melt during laser heating. Analysis of the signals determined by thereflection of laser radiation from the melt surface allows to determine the moments of change in the intensity of heat andmass transfer in a shorter time than when controlling the melt temperature. The results of the study can be used in thedevelopment of methods and tools for monitoring and operational control of the SLM process.
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