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 (TM) Pulverisette 7 Premium Line) up to 1.5h under argon (Ar) atmosphere. Annealing process was carried out in a tube furnace at 650 degrees 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 degrees C for as-blended powders and it shifts to about 272 degrees C for MA'd powders. Al-B powder blends MA'd for 9h and annealed have AlB2 particles in size between 35 and 75 nm in the presence cif Al13Fe4, Fe3B and Fe2B contaminations. (C) 2011 Elsevier Ltd. All rights reserved.