1. Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education; Harbin Institute of Technology; Harbin150080 P. R. China
2. National Key Laboratory for Precision Hot Processing of Metals; Harbin Institute of Technology; Harbin150080 P. R. China
3. Materials Research Group; Department of Mechanical Engineering; University of Southampton; Southampton SO17 1BJ UK
4. Departments of Aerospace & Mechanical Engineering and Materials Science; University of Southern California; Los Angeles CA 90089-1453 USA