1. School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University; Chengdu 610031 P.R. China
2. Bond and Band Engineering Group, Sichuan Provincial Key Laboratory (for Universities) of High Pressure Science and Technology, Southwest Jiaotong University; Chengdu 610031 P. R. China
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University; Xi'an 710072 P. R. China