Former research focusing on the understanding of the “smaller is stronger” paradigm in single crystals have demonstrated that the size dependent strengthening is different for fcc and bcc metals. Plasticity in bcc metals below the critical temperature Tc is generally less understood then plasticity in fcc metals. Researchers are still debating the occurrence of slip on slip planes other then those of the {110} family, the role of Schmid’s law, non-Schmid stresses and the core structure of the screw dislocation in the activation of slip systems. In computational models however, the description of plastic deformation is usually simplified by accepting that the flow stress and plastic deformation mechanisms in bcc metals are primarily controlled by the glide of ½ screw dislocations on {110} planes.
The micro-compression technique performed during in-situ Laue diffraction at the MicroXAS beamline of the Swiss Light Source [H. Van Swygenhoven, S. Van Petegem, JOM 62 (2010) 36.] has been used to follow the sequence of activated slip systems in BCC single crystal pillars with diameters of 1-2 micron. Diffraction patterns are obtained in transmission with a 5-23 keV X-ray beam, with FWHM of 0.5-1 μm and complemented with Laue scans allowing the mapping of the spatial distribution of strain gradients in the deformed pillars, providing information on local crystallographic orientations and on the activated dislocation slip systems. In-situ Laue diffraction is for the moment the only technique allowing following the microstructure of micron-sized single crystal pillars during deformation. In other words, this is an ideal technique to address long standing open questions in plasticity of bcc metals
In this project in-situ micro-compression experiments are carried out during Laue diffraction on four bcc single crystal pillars, i.e. Tungsten, Molybdenum, Niobium and Vanadium having different values of Tc.
The micro-compression technique performed during in-situ Laue diffraction at the MicroXAS beamline of the Swiss Light Source [H. Van Swygenhoven, S. Van Petegem, JOM 62 (2010) 36.] has been used to follow the sequence of activated slip systems in BCC single crystal pillars with diameters of 1-2 micron. Diffraction patterns are obtained in transmission with a 5-23 keV X-ray beam, with FWHM of 0.5-1 μm and complemented with Laue scans allowing the mapping of the spatial distribution of strain gradients in the deformed pillars, providing information on local crystallographic orientations and on the activated dislocation slip systems. In-situ Laue diffraction is for the moment the only technique allowing following the microstructure of micron-sized single crystal pillars during deformation. In other words, this is an ideal technique to address long standing open questions in plasticity of bcc metals
In this project in-situ micro-compression experiments are carried out during Laue diffraction on four bcc single crystal pillars, i.e. Tungsten, Molybdenum, Niobium and Vanadium having different values of Tc.