Department of Materials Physics and Chemistry;
School of Materials Science and Engineering;
and Key Laboratory for Anisotropy and Texture of Materials;
Ministry of Education;
Northeastern University;
Shenyang 110819;
China;
School of Materials Science and Engineering;
Shenyang University of Technology;
Shenyang 110870;
China;
ultrafine-grained; pure; Al; specimen; size; effect; strength; ductility;