1. a Karlsruhe Institute of Technology, Institute for Material Research II , Herrmann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen , Germany
2. b Department of Mechanical Engineering and Mechatronics , Karlsruhe University of Applied Sciences , Moltkestrasse 30, D-76133 Karlsruhe , Germany