1. School of Materials Science and Engineering; Harbin Institute of Technology; Harbin 150001 P. R. China
2. Key Laboratory of Engineering Dielectrics and Its Application; Ministry of Education; Harbin University of Science and Technology; Harbin 150080 P. R. China
3. School of Electrical and Electronic Engineering; Harbin University of Science and Technology; Harbin 150080 P. R. China
4. National Key Laboratory of Science and Technology on Precision Heat Processing of Metals; Harbin Institute of Technology; Harbin 150001 P. R. China
5. State Key Laboratory of Advanced Welding and Joining; Harbin Institute of Technology; Harbin 150001 P. R. China