Thermodiffusion in liquid binary and ternary alloys

Abstract

Thermodiffusion designates a diffusive motion of particles driven by a temperature gradient. In alloys, this effect can reduce the homogeneity of crystals. In situ X-ray radiography and ex situ energy dispersive X-ray spectroscopy were used to measure the thermodiffusion in liquid Ag-Al, Ag-Cu, Ag-Al-Cu, and Al-In. Thanks to the non-invasive in situ process, the time-dependent concentration distribution in liquid alloys could be measured, from which the interdiffusion coefficient also could be derived. For Ag-Al, where Ag migrated to the cold side, the interdiffusion coefficient was compared with previously published values, and the agreement confirmed the experimental process. For Ag–Cu and Ag-Al-Cu, no migration of Cu was observed. For Al-In, which shows a miscibility gap in the liquid, a very low interdiffusion coefficient and correspondingly high Soret coefficient was measured.