A deep knowledge of phase relationships involving a liquid phase is of critical interest in solidification process. If chemically active elements are involved, the conditions under which phase equilibria will be studied should be carefully defined. An illustration is given by the investigation of the Fe-rich corner of the Fe-Ti-B system between 1200 and 1450 A degrees C, for which Ti and B reactivity, very low solubility and flotation effects of TiB2 should be taken into account. The strategy is to combine both static and dynamic methods. Electromagnetic phase separation technique, developed at our laboratory, allows to determine phase field boundaries in the liquid/solid domains at selected temperatures and to locate univariant lines on a liquidus projection. Differential thermal analysis is supplemented by characterization of resulting microstructures to establish liquidus temperature of selected alloys and to evaluate ternary invariant points. These new experimental data may be used as a basis for a relevant thermodynamic description of the investigated ternary system.