In situ Measurement of Thermodiffusion in Liquid Alloys

Temperature gradients can change the concentration distribution in multicomponent materials. This cross-coupling effect of heat and mass transfer is difficult to measure in liquid alloys. We present a new method using x-ray radiography in combination with a high temperature furnace to measure thermodiffusion in melts time and space resolved. This greatly improves the process control and allows us to determine diffusion and thermodiffusion simultaneously. In a first experiment we demonstrate that in liquid Al_{78.5}Ni_{21.5} the component nickel diffuses to the cold end of the sample with a Soret coefficient on the order of 10^{-3} K^{-1}.