Thermodynamics and kinetics of transition metal borides formation in molten aluminium

Aluminium is widely used for overhead cables after the removal of vanadium (V), titanium (Ti), zirconium (Zr) and chromium (Cr) impurities that deteriorate its electrical conductivity. These impurities are removed in casthouse by the addition of Al-B (AlB12/AlB2) master alloys called boron treatment. In the current study, thermodynamics analysis of transition metal impurities removal from molten aluminium was investigated using FactSage and HSC chemistry. Kinetics analysis of VB2 formation in molten aluminium was also carried out. It was established that the kinetics of VB2 formation was controlled by the liquid phase mass transfer in the early stage of reaction. The second stage was controlled by the diffusion of [B]/ [V] through VB2 layer formed in the first stage. Finally, recommendations were given to industry based on the industrial trials and laboratory investigations that may help to improve current boron treatment of molten aluminium.