THERMODYNAMIC ANALYSIS OF Ti, Zr, V AND Cr IMPURITIES IN ALUMINUM MELT

摘要

Aluminum is widely used as the main material for overheadpower cable because of its good electrical conductivity and lightweight. Metal impurities, in particular Ti, Zr, V and Cr in thesolution, affect the electrical conductivity of aluminumsignificantly. Industrially, boron treatment has been used toremove these impurities through the formation of borides.However, studies have shown that solution thermodynamics andthe detailed reaction mechanisms of the borides formed inaluminum melts are not well understood. In the present work,thermodynamic analysis has been carried out to investigate therelative stability and to elaborate on the preferential formation ofvarious borides in aluminum melt. It is shown that diborides(MB_2) are the most thermodynamically stable boride compoundsof these impurities in the given working conditions. The ZrB_2,TiB_2 and VB_2 phases are more stable compared to AlB2 and CrB_2hence do not dissolve readily. It is also shown that the relativestability of the boride phases is affected by the presence of othermetal diborides.