A03 – Atomic Scale Characterisation of Dislocations, Planar and Point Defects

PI(s): Joachim Mayer (RWTH/GFE)

SFB researchers: Marta Lipińska-Chwałek (FZJ/ER-C), Joshua Spille (RWTH/GFE)

Engineering of advanced structural materials by incorporation of low-dimensional microstructural elements or defect phases, which is the main aim of the CRC 1394, can only be reached if a full characterization of these property-controlling components can be accomplished down to the atomic-level.

In the present project, the most advanced high-resolution imaging (STEM/HAADF, NCSI TEM, 4DSTEM), diffraction (SAED, CBED and NBED) and analytical (EDX, EELS) techniques based on aberration corrected, high resolution (scanning) transmission electron microscopy (HR(S)TEM) are employed to elucidate the structure-property relationships of defect phases. Combination of these advanced techniques provides high throughputs of structural information from one experiment and allows us to analyze the data in many different ways, thereby providing high three-dimensional information on the shape, structure and composition of defect phases.

The materials provided by projects S, A01, A05, B02, C01 and C02 are investigated in project A03 with respect to the structural and chemical properties of the structural defects - from 0D defects, like impurity atoms and small ordered clusters, via 1D defect phases, i.e. dislocations in the bulk and at interfaces, up to planar 2D defect phases like stacking faults and grain boundaries, including special boundaries as twin boundaries. The analyses are performed in close cooperation with projects A01, A02, A04, A05, A06, B01 and B03. Our high-resolution (HR) results are handed over to project A04 for further processing while structural and analytical data are shared with projects A01, A02, A06, B06, C01, C02, C04, C05 and C06 for comparison and as input for the modelling and simulation activities.

Consequently, project A03 directly contribute to the defect phase diagrams “Dislocations”, “Stacking faults”, and “Grain boundaries” of Mg solid solutions and the intermetallic phases. Example of the workflow related to the topic of deformation transfer in composite samples is shown in Fig. 1.

Sample preparation and conventional TEM analysis is performed at the Central Facility for Electron Microscopy (GFE) of RWTH Aachen University, while advanced (S)TEM measurements are conducted at the Ernst Ruska-Centre (ER-C), which is one of the leading infrastructures in terms of aberration-corrected TEM operated jointly by RWTH Aachen University and Forschungszentrum Jülich.




Figure 1: Example SFB 1394 workflow, applied for the topic of deformation transfer in composites [1]: after deformation analysis (a), macroscopic characterization and identification of the deformation transfer sides (b) by projects A5 and C2, detailed HR(S)TEM imaging of the deformation defects is performed in A3 project. HR data are processed in A4 to improves the quality and signal to noise ratio of the STEM data and facilitates obtaining atomic insights into defects structure (A3). The latter information is then shared with the project A2 for the modelling and simulation of the defects structure and deformation processes.



  • [1] J. Guénolé, M. Zubair, S. Roy, Z. Xie, M. Lipińska-Chwałek, S. Sandlöbes-Haut, S. Korte-Kerzel (2021) Exploring the transfer of plasticity across Laves phase interfaces in a dual phase magnesium alloy, Materials and Design 202, 109572 – https://doi.org/10.1016/j.matdes.2021.109572
  • [2] M. Zubair S. Sandlöbes-Haut, M. Lipińska-Chwałek, M.A. Wollenweber, C. Zehnder, J. Mayer, J.S.K.-L. Gibson, S. Korte-Kerzel (2021) Co-deformation between the metallic matrix and intermetallic phases in a creep-resistant Mg-3.68Al-3.8Ca alloy, Materials and Design 210, 110113 - https://doi.org/10.1016/j.matdes.2021.110113
  • [3] J. Li, X. Zhou, J. Su , B. Breitbach, M. Lipińska-Chwałek, H. Wang, G. Dehm (2022) Elucidating dynamic precipitation and yield strength of rolled Mg-Al-Ca-Mn alloy, Materials Science & Engineering A 856, 143898 -  https://doi.org/10.1016/j.msea.2022.143898
  • [4] J.Lia, X. Zhou, A. Breen, Z. Peng, J. Su, P. Kürnsteiner, M. J. Duarte Correa, M. Lipińska-Chwałek, H.Wang, D. Holec, J. Mayer, G. Dehm (2022) Elucidation of formation and transformation mechanisms of Ca-rich Laves phase in Mg-Al-Ca-Mn alloys, Journal of Alloys and Compounds 928,  167177 - https://doi.org/10.1016/j.jallcom.2022.167177