Oral Presentation 24th Australian Conference on Microscopy and Microanalysis 2016

Exploring microstructure-property-relationships of crystalline materials by application of diffraction techniques (electron backscatter diffraction, EBSD, and electron channelling, ECCI) in the SEM  (#49)

Stefan Zaefferer 1 , Guillaume Stechmann 1 , Peter Konijnenberg 1 2 , Lars Schemmann 3 , Sumantra Mandal 4
  1. Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
  2. Bruker Nano, Berlin, Germany
  3. Salzgitter-Mannesmann Forschung, Duisburg, Germany
  4. Indian Institute of Technology (IIT) Kharagpur, Kharagpur, India

Traditionally microstructures are investigated by microscopic techniques while properties are measured by macroscopic measurements. Scanning electron microscopy, together with its quantitative microstructure characterization tools, is able to bridge the scales and allow exploring the correspondence between microstructural elements and related properties. This contribution will show how the techniques work and, on a number of examples from different materials, how the microstructure-property correspondence is made.

Orientation imaging microscopy (OIM) based on electron backscatter diffraction (EBSD) allows, in the limits of its spatial resolution, quantitative characterization of a variety of microstructural elements: dislocation densities are characterized in two classes: geometrically necessary dislocation (GND) densities can directly be determined from measured crystal lattice rotations. Statistically stored dislocation (SSD) densities are measured with a new approach using Kikuchi band profile analysis. The 5 rotational parameters of grain boundaries are determined by 3-dimensional OIM realized by a serial sectioning approach, either performing FIB tomography or mechanical polishing tomography. The fraction of different phases and their composition is directly returned by combination of crystallographic analysis via EBSD and compositional analysis via x-ray spectroscopic methods.    

Electron channelling contrast imaging (ECCI) is largely complementary to OIM as it allows direct observations of individual lattice defects, namely dislocations, nano-scaled twins, and nano-scaled precipitations in a similar manner than in TEM but on bulk specimens.

3 examples will be shown to illustrate the combination of microstructure and property characterization: the effect of grain boundaries on the efficiency of CdTe thin film solar cells is investigated by a combination of 3D OIM and cathodoluminescence. The corrosion resistance of stainless steel boundaries is studied by use of 3D OIM. The strength of dual phase steels is investigated by combination of different OIM techniques, ECCI and micro-cantilever bending.