Abstract:Two mixing techniques, the immersion method and the vortex method, were adopted in the production of Al-3%B master alloys since the generally used production route involving the direct addition of KBF₄ salt to molten aluminum has several drawbacks. The experimental results demonstrate that the Al-B master alloys produced by the immersion method show a microstructure characterized by the appearances of AlB₁₂ phase and many agglomerations of boride particles, while the Al-B master alloy produced by the vortex method exhibits a well dispersed microstructure of AlB₂ particles in the matrix. The distinct microstructure features result from the differences in the stirring speed during the salt additions and the average size of the salt droplets achieved by the salt additions.

Key words: Al-B master alloy; agglomeration; AlB₁₂; mixing technique