1. School of Materials Science and Engineering, National Engineering Research Center of Waste Resource Recovery; Kunming University of Science and Technology; Kunming 650093 Yunnan Province P. R. China
2. College of Science; Armed Police Engineering University; Xi'an Shaanxi Province P. R. China
3. State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 Shaanxi Province P. R. China