Evolution of diffraction pattern of probing radiation reflected by a silver surface upon melting

Evolution of the diffraction pattern was studied experimentally using a sample of silver with a moderately rough surface formed by the composition of predominantly unidirectional grooves. The sample was heated in a tubular electric furnace; its temperature was determined by a thermocouple measurement. At a temperature close to the liquidus temperature, the appearance of isotropically scattered radiation, concentrated near the specular beam, is detected. We analyzed the evolution of these radiation components upon melting and showed that the nucleation is the source of isotropic scattering. It is found that the evolution of the diffraction pattern enables one to observe the melting of the surface layer, accompanied by the simultaneous existence of the disappearing solid phase and the growing liquid phase. Spreading of the sample melt over a substrate can be also observed with the diffraction pattern.