1. National Engineering Research Center of Light Alloy Net Forming School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 P. R. China
2. State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 P. R. China
3. Center of Hydrogen Science Shanghai Jiao Tong University Shanghai 200240 P. R. China
4. Department of Materials Science and Engineering University of Michigan Ann Arbor MI 48109‐2136 USA