Exothermic and Slag Formation Behavior of Aluminothermic Reduction of Mo and V Oxides

Vanadium (V), molybdenum (Mo), and aluminum (Al) are important alloying elements in titanium alloys, typically introduced through master alloys such as V-Al and Mo-Al. Current preparation of these master alloys predominantly relies on the spontaneous reduction of V2O5 or MoO3 by aluminum. However, separate production and addition of master alloys increase the cost of the titanium alloy. Insufficient understanding of the exothermic behavior and slag-forming process during the aluminothermic reaction often leads to low alloy yield and elevated impurity levels due to splashing and poor alloy–slag separation. This study focused on the controllable aluminothermic reaction of V2O5 and MoO3 to produce high-quality and high-yield V/Al/Mo alloy. Thermodynamic calculations indicate that the reduction of MoO3 to Mo by aluminum is more favorable than the reduction of V2O5 to V. Al% in the V-Al-Mo alloy is crucial for controlling reaction temperature. When the Al/O ratio in the raw materials exceeds 1.0, increasing aluminum reduces both the reaction exothermicity and theoretical reaction temperature. A combination of thermodynamic calculations and high-temperature experiments demonstrates that the heat generation and slag composition can be effectively controlled by Al/O ratio in raw materials. When the Al/O ratio in raw materials is 1.6–2.0, the yields of Mo and V exceed 99% and 95%, respectively. This study provides an effective approach to producing V/Al/Mo alloy under controllable conditions, which shows great potential for other aluminothermic reactions. Extensive solid solutions of V/Al/Mo also provide invaluable data for the optimization of the alloy database.