1. Federal Institute for Materials Research and Testing (BAM) Unter den Eichen 87 12205 Berlin Germany
2. Department of Materials Science and Engineering University of Illinois at Urbana‐Champaign Urbana IL 61801 USA
3. IWF Technical University Berlin Pascalstr. 8–9 10587 Berlin Germany
4. Institute of Non‐Metallic Materials Clausthal University of Technology 38678 Clausthal‐Zellerfeld Germany