1. Materials Testing Institute (MPA), University of Stuttgart, Pfaffenwaldring 32, Stuttgart 70569, Germany e-mail:
2. Professor Materials Testing Institute (MPA), University of Stuttgart, Pfaffenwaldring 32, Stuttgart 70569, Germany e-mail:
3. Siemens AG, Energy Sector, Rheinstraße 100, Mülheim an der Ruhr 45478, Germany e-mail: