1. Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of Education Taiyuan University of Technology Taiyuan 030024 P. R. China
2. Materials Institute of Atomic and Molecular Science Shanxi University of Science & Technology Xi'an 710021 P. R. China
3. Shanxi Yuci Broad Wire Products Co., Ltd Jinzhong, Yuci 030600 P. R. China