Phase transformation and gas–solid reaction of Al2O3 during high-energy ball milling in N2 atmosphere

Abstract

Abstract Al 2 O 3 powders were milled in N 2 atmosphere using an attritor ball mill. The phase transformation and gas–solid reaction of Al 2 O 3 during high-energy ball milling in N 2 atmosphere were investigated. It is found that the γ-Al 2 O 3 transform to α-Al 2 O 3 as milling time increases. Milled for 20 h in N 2 atmosphere, Al 2 O 3 becomes partially amorphous and the gas–solid reaction between Al 2 O 3 and N 2 takes place. A new phase with cubic aluminum nitride (AlN) structure forms during milling which is different from normal hexagonal AlN produced by carbon thermal reduction processing. As milling energy increases, the amount of this new phase with cubic AlN structure increases. The amount of this new phase is as high as 72% when Al 2 O 3 is milled in N 2 atmosphere at 650 rpm for 40 h.