Electron microsocpy: a powerful tool for understanding the fundamental deformation mechanisms of materials

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Master & doctoral Researchers

Description:

In the aim of following the fast evolution of the industrial demands, developing innovative techniques that allow to understand and to predict the mechanical properties of materials has become a necessity for the Materials Science community. For instance, mechanical tests combined with microstructural investigations provide engineers with the necessary information to computationally predict the mechanical performance of components. Such experiments allow capturing footprints of the deformation mechanisms responsible for the changing microstructure.

The Transmission Electron Microscope (TEM) is one of the most well-known techniques for observing and characterizing dislocations in electron transparent thin foils (thickness of about 100 nm with a useful field of view of few ┬Ám2 only). Comprehensive dislocation studies at microscopic scale bring valuable information for extrapolating to the macroscopic mechanical response of materials and they can feed numerical advanced multiscale crystal plasticity models.

Characterization of a dislocation configuration by TEM (from Guitton et al., Philos. Mag., 2012)

Full characterization of dislocations is not only synonym of TEM experiments on thin foil samples. Scanning Electron Microscope (SEM) can access diffraction contrast on bulk materials with the phenomenon of electron channeling. Electron channeling is due to electrons, that channel down the crystal planes i.e. paths where electrons can penetrate to a higher depth before scattering. Some orientations of the crystal will backscatter more electrons than others, giving rise to orientation contrast.

Planning: (June – August 2021, online)
  • Chapter 1: basics of materials plasticity (2 hours)
  • Chapter 2: basics of physics of electron-matter interactions (3 hours)
  • Chapter 3: basics of contrast theory of crystalline defects in transmission electron microscopy (3 hours)
  • Chapter 4: contributions of the scanning electron microscopy to plasticity of materials (2 hours)