1. Department of Engineering Mechanics, School of Naval Architecture, Ocean and Civil EngineeringShanghai Jiao Tong University Shanghai 200240 China
2. Department of Mechanical EngineeringMassachusetts Institute of Technology Cambridge MA 02139 USA
3. Laboratory for NuclearMaterials, Nuclear Energy and Safety DepartmentPaul Scherrer Institute PSI Villigen 5232 Switzerland
4. Laboratory of Metal Physics and Technology, Department of Materials ETH Zurich, 8093 Zurich Switzerland