The Formation and Growth Behavior of Aluminium Boride Crystals in an Al–B Alloy

Abstract

The formation of borides in an Al–3 wt.% B alloy produced from reaction between aluminium and boron oxide (B2O3) has been investigated. Melting and cooling experiments were carried out to explore the growth characteristics of aluminium boride crystals. During heating up to1300 oC boron dissolved into molten aluminium and subsequently cooled to form solid aluminium borides in the aluminium matrix. At room temperature boride particles was identified as AlB2. Although, AlB12 phase is the first phase to form directly from the Al-B liquid above 1000 oC which transforms to stable AlB2 crystals by a peritectic reaction during cooling. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were employed. Results showed that the shape and distribution of the borides are dependent on the cooling conditions of the liquid Al-B alloy.