1. State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi'an Jiaotong University 1 , Xi'an 710049, China
2. School of Materials Science and Engineering, Harbin Institute of Technology at Weihai 2 , 2 West Wenhua Road, Weihai 264209, China
3. Department of Physics, Yantai University 3 , Yantai 264005, China