Direct Measurement of Mobility of Edge and Screw Dislocations in 3% Silicon-Iron by High Voltage Transmission Electron Microscopy

Effects of Temperature and Strain Rate on Deformation Twinning in Fe-Si Alloy

“…Key words : magnetic steel; Fe-Si alloy; deformation twin; strain rate; temperature; brittle fracture. 26 …”

Effects of Temperature and Strain Rate on Deformation Twinning in Fe–Si Alloy

“…Next, the temperature and strain rate dependencies of the area fraction of the deformation twin and twin width are discussed from the point of view of the dislocation velocity. The velocity of dislocation motion in a Fe-Si alloy was measured by Saka and Imura, 25,26) Erickson, 27) Stein and Low, 28) and Moon and Vreeland. 29) They reported that the relationship between velocity, ν, and applied shear stress resolved for the slip plane, τ, is as follows: Where σ y represents the yield stress of a specific sample and τ c represents the critical resolved shear stress of the activated slip system.…”

Stimulation of use of in-situ experiments in high voltage electron microscopes in advancing science and technology

“…In 1967, a TV-VTR system was introduced to HVEM in-situ experiments for the first time as an image recording system by our Nagoya group [4,[14][15][16] and continuous fast recording by this system of the images of dislocations moving under a controlled stress-strain condition was initiated [4,6,7,17] [6,7,17,18]. Of course, some size effects may be found, so that absolute values of load and elongation measured with a thin specimen may differ somewhat from those measured with bulky specimens and the accuracy of the measurement of cross-sectional area of the specimen for obtaining the applied stress is not so high as compared with bulky specimens, but even so, the technique described in the references [5] and [6] is good enough to mâke a direct correlation between the moving dislocation and the stress-strain state of the specimen with a reasonable accuracy.…”

“…Of course, some size effects may be found, so that absolute values of load and elongation measured with a thin specimen may differ somewhat from those measured with bulky specimens and the accuracy of the measurement of cross-sectional area of the specimen for obtaining the applied stress is not so high as compared with bulky specimens, but even so, the technique described in the references [5] and [6] is good enough to mâke a direct correlation between the moving dislocation and the stress-strain state of the specimen with a reasonable accuracy. Figure 1 indicates a schematic representation of a complete assembly for carrying out HVEM in-situ straining experiments.…”

“…By the development of these HVEMs, transmission observation of thick foil specimens of the order of am thick became possible [1][2][3] and facilitated in-situ observations of behavior of lattice defects [4][5][6][7][8][9] and other structural entities as well as in-situ observations of radiation damages caused by high energy electrons and ion irradiation [10,11]. However, it should be recognized here that in the case of the behavior of, for instance, lattice defects like dislocations which accompany widely spread lattice strain, the density of defects and the behavior of them change greatly when one uses a thin foil specimen of the thickness of less than a critical value [12,2,7].…”