Aluminum diboride synthesis from elemental powders by mechanical alloying and annealing

In this study, AlB2 powders were synthesized by using a combined method of mechanical alloying (MA) and annealing of elemental aluminum (Al) and boron (B) powders. Milling was performed in a planetary ball-mill (Fritsch™ Pulverisette 7 Premium Line) up to 15 h under argon (Ar) atmosphere. Annealing process was carried out in a tube furnace at 650 °C for 6 h under Ar atmosphere. The effects of MA durations on the annealing process and AlB2 formation were investigated. The conversion of Al and B powders to AlB2 starts after only MA for 3 h or after MA for 1 h and subsequent annealing. A slight formation of AlB12 occurs at 242 °C for as-blended powders and it shifts to about 272 °C for MA’d powders. Al–B powder blends MA’d for 9 h and annealed have AlB2 particles in size between 35 and 75 nm in the presence of Al13Fe4, Fe3B and Fe2B contaminations.