Materials World Network: Interaction of time- and load history dependent degradation of multilayered materials subjected to high temperatures

• Applicants: Professorin Dr.-Ing. Marion Bartsch; Professor Dr.-Ing. Gunther Eggeler
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 43454675

Multilayered materials subjected to high temperatures exhibit time and temperature dependent evolution such as interdiffusion, precipitating and dissolution of phases, along with chemical reactions especially at the interfaces of dissimilar materials. In most applications cycling loads are superposed. The interaction between time-dependent processes and degradation due to cyclic loads is highly non-linear. Thus, it is difficult to use here common approaches of accelerated testing for lifetime assessment under realistic loading conditions. On the other hand, reproducing realistic load spectra and realistic time scales in laboratory environment is in most cases not possible or impractical because of long testing times.We propose to develop a combined experimental and numerical technique for accelerated testing and life-time prediction of material systems with joints of dissimilar materials at high temperatures. This method incorporates fundamental materials science and applied mechanics. A set of carefully selected test sequences with combined thermal and cyclic loading will be conducted and subsequently, the respective degradation status will be investigated by means of microscopic and microanalytic methods. The underlying mechanisms will be identified and used for mechanism based modelling and numerical simulation of the materials behaviour. From successive experiments and simulations it is expected to achieve parameters describing the interaction of the governing mechanisms, which will be used for lifetime assessment. The numerical simulations will reduce the experimental effort and the required testing time.

• DFG Programme: Research Grants
• International Connection: USA
• Participating Person: Anette Karlsson, Ph.D.