1. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
3. Materials Department, University of California Santa Barbara, Santa Barbara, California 93106, United States
4. Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
5. Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States