1. Department of Mechanical Engineering, N104 Walter Scott Engineering Center, University of Nebraska-Lincoln, Lincoln, NE 68588-0656, USA
2. Department of Mechanical Engineering, 3027 H.M. Black Engineering Building, Iowa State University, Ames, IA 50011-2161, USA
3. Materials Science and Technology Division &, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Road, MS-6056, Oak Ridge, TN 37831-6056, USA