Mechanism of VB2 formation in molten aluminium

Smelter grade aluminium is used for electrical grade conductor applications. Impurities present in solution, especially transition metals such as V, Ti, Zr and Cr reduce the electrical conductivity of smelter grade aluminium [1-2]. In the cast houses, these impurities such as V, Ti, Zr and Cr are removed by the addition of Al-B (AlB12/AlB2) master alloys, called boron treatment [1-7].The thermodynamic analysis of transition metal impurities in molten aluminium [8], it was predicted that the order of impurities removal will be from Zr and Ti to V in the temperature range of 650 degrees C to 900 degrees C. It was further predicted that diborides of transition metals are more stable as compared with their other possible borides in the temperature range investigated [8]. Although the process for the removal of transition metal impurities is explained in literature, limited information has been reported related to the kinetics of process and the mechanism of borides formation. For the better understanding of boron treatment of molten aluminium, kinetics experiments were performed. In this paper, selected results and the mechanism of VB2 formation in molten aluminium are presented.