Nanosized α-alumina powders were prepared by use of the high energy ball milling process from fine grain γ-alumina powders without heat treatment. The γ-alumina transformed to α-alumina powder with a size of about 26 nm by the milling process at 720 rpm for 10 h. It was concluded that the mechanical stress induced by the milling process was effective to produce the nanosized alumina powder.
