Kinetic contributions rule diffusion of mass in the liquid ternary eutectic E1 Ag-Al-Cu alloy

In ternary alloy systems, the mass diffusion of one component can be influenced by interactions with other constituents caused by their chemical concentration gradients. The diffusion coefficients of the ternary system around its eutectic composition (Al69.1Ag18.1Cu12.8 [at%]) were measured in the liquid state. The ex-situ shear cell method combined with in-situ neutron radiography measurements of diffusion couples processed in a long-capillary, as a benchmark experiment, provides significantly enhanced accuracy compared to the long capillary method with postmortem analysis. Based on these measurements, it is shown that no uphill diffusion occurs. This result is supported by the obtained diffusion matrix. The diffusion coefficients obtained from the shear cell and neutron radiography experiments coincide within their margins of error of 10 %. Complementary quasi-elastic neutron scattering measurements of self-diffusion show that interdiffusion and self-diffusion agree in the eutectic Al-Ag-Cu melt, revealing the dominant influence of kinetic contributions to interdiffusion.