1. Institute of Nonferrous Metal Gradient Materials Preparation and Performance, Chengdu Normal University, No. 99, Haike Road, Eastern Section, Chengdu, Sichuan 611130, P. R. China
2. College of Physics and Engineering, Chengdu Normal University, No. 99, Haike Road, Eastern Section, Chengdu, Sichuan 611130, P. R. China
3. Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China