Investigation of Marangoni convection in monotectic melts by resistance measurements

Electrical resistance of monotectic melts strongly depend on the state of phase separation. The gravity driven sedimentation leads to an arrangement of the lighter phase above the heavier one. Because the resistance of the phases differ, the state of demixing can be determined by the overall melt resistance using the four-probe method. Resistance of hypermonotectic Zn–Pb liquid alloys is measured in a wide temperature range between 820 °C and the monotectic line and its dependence on different parameters is discussed. The results are compared with theoretical predictions. It is shown that the electrical resistance of the demixed melt changes if transport processes (Marangoni convection) take place under microgravity conditions. The measuring arrangement used in the microgravity experiment on Zn–Pb melts during the flight of TEXUS 39 is presented.