Current Events:


Single-crystalline Nickel based superalloys are the state-of-the-art material system for high-temperature applications in harsh environments and under high loads (e.g., aircraft engines). To understand the creep behavior it is important to follow the microstructural and chemical evolution during deformation and to draw the connection to the complicated superdislocation configurations and core structures.In our studies we combine advanced high-resolution and analytical TEM techniques as well as convergent beam electron diffraction techniques for investigation of local composition, strain and defects in the γ/γ’-microstructure and its interfaces. One important goal is to contribute to the understanding of the formation and thermally activated glide and climb of the superdislocations.

Selected Publications

  • J. Müller, G. Eggeler and E. Spiecker, On the identification of superdislocations in the γ'-phase of single crystal Ni-base superalloys - an application of the LACBED method to complex microstructures, Acta Materialia 87 (2015) 34-44.
  • A.B. Parsa, P. Wollgramm, H. Buck, Ch. Somsen, A. Kostka, I. Povstugar, P. Choi, D. Raabe, A. Dlouhy, J. Müller, E. Spiecker, K. Demtröder, J. Schreuer, K. Neuking, G. Eggeler, Advanced scale bridging microstructure analysis of single crystal Ni-base superalloys, Adv. Eng. Mat., 17 (2015) pp. 216–230
  • J. Müller and E. Spiecker, Dislocation characterization by means of large angle convergent beam electron diffraction, European Microscopy Congress EMC2012, Manchester, 16.-21. Sept. 2012, pp. 856-857.
  • J. Müller, F. Niekiel and E. Spiecker, Simultaneous strain and chemical mapping applied to Ni-based superalloys, Microscopy Congress MC2013, Regensburg, 25.-30. Aug. 2013, Proc. (Part 1), pp. 638-639.
  • Y. Eggeler, J. Müller, M.S. Titus, A. Suzuki, T.M. Pollock, E. Spiecker TEM analysis of localized, planar deformation events which govern creep of single crystalline CoNi-superalloys with γ/γ́-microstructures Microscopy Congress MC2013, Regensburg, 25.-30. Aug. 2013, Proc. (Part 1), pp. 771-772.