Self-diffusion in liquid Al-Ge investigated with quasi-elastic neutron scattering

Abstract

Quasi-elastic neutron scattering measurements are carried out to investigate the self-diffusion of Ge in liquid Al-Ge alloys in a wide temperature range at and below the melting point of the respective pure elements. In all investigated Al-Ge alloys, the self-diffusivity of Ge follows an Arrhenius behavior over the entire investigated temperature range and shows a standard deviation of only 4%, which is significantly more precise when compared to classical measurements in long capillaries. At the melting point of pure Ge, the self-diffusivity of Ge in all investigated alloys is higher by some 22%–28% than that of pure Ge and shows a diffusion maximum at 41 at. % Ge. This can be understood as an increase in chemical interactions between Al and Ge in this composition region and is in line with previous experimental findings regarding fast dendrite growth during solidification.