The solid-liquid interface energy plays a major role in solidification processes. It is this quantity that governs the length scales of solidification morphologies (microstructure fineness). The grain boundary groove in an applied temperature gradient-method is one of the most common techniques to directly measure the Gibbs-Thomson coefficient and has been applied to determine the solid-liquid interface energy for binary and ternary alloy systems. In order to measure the solid-liquid interface energy in ternary alloy systems, a radial heat flow apparatus has been assembled. This apparatus permits to maintain a stable temperature gradient for hours and thus to equilibrate a grain boundary groove with the corresponding liquid. The sequence of the experiment is composed by three different steps: The calibration of the thermocouples, the optimisation of temperature control, and the annealing process. After rapid quenching, the samples have been metallographically investigated and the local curvature of the grooves have been analysed. From this information and the determination of the local undercooling and curvature the solid-liquid interface energy can be evaluated. In the present work, the radial heat flow apparatus has been further optimized to produce the grain boundary groove shapes for solid alpha-, theta- and zeta- Phases in the Al-Cu-Ag ternary system.