Shear Induced Low- and High-Angle Boundary Characterization Using Kikuchi Bands in Transmission Electron Microscopy

Marcello Cabibbo

doi:10.4028/www.scientific.net/MSF.584-586.293

Paper Titles

Structure of Triple Junctions of Grains, Nanoparticles in them and Bending - Torsion in Metal Nanopolycrystals
p.269

Workability Limits of Commercial Purity Titanium Subjected to Equal Channel Angular Pressing
p.275

Specific Features of Static, Impact, and Fatigue Fracture of the 0.09%C-0.08%Mo-0.03%Nb-0.06%V Steel with Ultrafine-Grained Structure
p.281

Compressive Behavior of Ultrafine-Grained Mg-Zn-Y-Zr Alloy Containing Quasicrystalline Phase
p.287

Shear Induced Low- and High-Angle Boundary Characterization Using Kikuchi Bands in Transmission Electron Microscopy
p.293

Microstructure Evolution during High Pressure Torsion of AZ80 Magnesium Alloy
p.300

Microstructure of a Metal-Polymer Composite Processed by Severe Plastic Deformation
p.306

Influence of SPD by ECAP on Cu Properties
p.310

Enhanced Strength and Ductility in Hypo-Eutectoid Cu-Al Alloys through ECAP and Annealing
p.315

HomeMaterials Science ForumMaterials Science Forum Vols. 584-586Shear Induced Low- and High-Angle Boundary...

Shear Induced Low- and High-Angle Boundary Characterization Using Kikuchi Bands in Transmission Electron Microscopy

Abstract:

Microstructure evolution with equal channel angular pressing (ECAP) using route Bc, that is a 90° axial rotation of the billet between passes, up to 8 passes, was investigated by transmission electron microscopy. The study has been focused on the induced development of boundary misorientation and spacing toward microstructure refinement. Cell (low-angle) and grain (high-angle) misorientation and spacing were determined from about 250 boundaries per pass of ECAP, systematically using whether Kikuchi patterns or Moiré fringes, these latter where possible. The average cell size and misorientation saturate within the first two passes. Misorientation and spacing of high-angle boundaries decrease with the number of passes. After 8 passes, mean cell size is ≈ 1.3 µm and the fraction of high-angle boundaries is ≈ 0.7. Differences in rate of grain structure evolution per pass are linked to differences in ability of dislocations introduced in new passes to recombine with the existing ones. As ECAP strain rises, the misorientation distribution develops strong deviations from the MacKenzie distribution for statistical grain orientation. This is interpreted as a result of the tendency to form equiaxed grains in a textured grain structure.