1. Faculty of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China
2. Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China
3. Faculty of Engineering, University of Waikato, Hamilton 3240, New Zealand
4. City College, Kunming University of Science and Technology, Kunming 650093, China
5. The National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China