Synthesis and characterization of mechanically alloyed Al/Al xMg1-xB2 composites

Abstract

The use of high energy ball milling (HEBM) was investigated as an alternative method to synthesize aluminum matrix composites reinforced with AlxMg1-xB2 particles. HEBM allowed achieving appropriate mixing and wettability between the composite components. After a 900°C treatment under vacuum, the resulting material had a mixed microstructure of dispersoids and submicron AlxMg1-xB 2 (hereon also referred as (AlMg)B2) particles embedded in the Al matrix containing also β (Al3Mg2) + Al eutectic. After processing the size distribution of AlxMg 1-xB2 particles included large particles (<23um) and submicron ones. Vickers microhardness measured on the composite matrix revealed that the highest matrix hardness was obtained in samples containing 5 wt.% AlxMg1-xB2 where larger amounts of nanosized reinforcement particles were present. X-ray diffraction studies showed the formation of AlxMg1-xB2 in the mechanically alloyed composites. In summary, the results buttressed the feasibility of fabricating a stronger Al-based composite via HEBM.