In this work a thermodynamic model based on molar Al/TiO_2 ratio, CaO content in slag and energy density was created to describe aluminothermic reduction. The influence of these parameters was theoretically calculated and experimentally proofed. The high solubility of γ-TiAl for oxygen doesn't allow to produce γ-TiAl with low aluminium content and low oxygen content (below 500 ppm) at the same time. Therefore, a second reduction step with Ca is necessary. Thermodynamic calculations showed that a Ca containing CaF_2 slag is able to decrease oxygen content in γ-TiAl below 100 to 250 ppm depending on the molar slag/metal ratio and Ca content in the slag. A pilot electro slag remelting unit is used to proof these calculations. In opposite to common aluminothermic process the produced liquid metal is directly cast without contact to air into a water cooled copper mould. This eliminates the difficult process step of impacting γ-TiAl pieces to an electrode after the won ingot has been crushed.
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