1. Research Center of Gansu Military and Civilian Integration Advanced Structural Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, 967 Anning East Road, Lanzhou 730070, P. R. China
2. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Key Laboratory of Nonferrous Metal Alloys and Processing, Ministry of Education, School of Materials Science & Engineering, Lanzhou University of Technology, 36 Langongping Road, Qilihe District, Lanzhou 730050, P. R. China