scholarly journals Effects of Unidirection/Bidirection Torsional Thermomechanical Processes on Grain Boundary Characteristics and Plasticity of Pure Nickel

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 236
Author(s):  
Yao Lin ◽  
Shan Liu ◽  
Tao Wu ◽  
Guangchun Wang
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Pure Nickel ◽  
Random Boundary ◽  
Special Boundaries ◽  
Grain Boundary Characteristics ◽  
Thermomechanical Processes ◽  
Boundary Characteristics ◽  
Boundary Modification ◽  
Boundary Characteristic

The “torsion and annealing” grain boundary modification of pure nickel wires with different diameters was carried out in this paper. The effects of torsional cycles as well as unidirectional/bidirectional torsion methods on grain boundary characteristic distribution and plasticity were investigated. The fraction of special boundaries, grain boundary characteristic distributions and grain orientations of samples with different torsion parameters were detected by electron backscatter diffraction. Hardness measurement was conducted to characterize the plasticity. Then, the relationship between micro grain boundary characteristics and macro plasticity was explored. It was found that the special boundaries, especially Σ3 boundaries, are increased after torsion and annealing and effectively broke the random boundary network. The bidirectional torsion with small torsional circulation unit was the most conducive way to improve the fraction of special boundaries. The experiments also showed that there was a good linear correlation between the fraction of special boundaries and hardness. The plasticization mechanism was that plenty of grains with Σ3 boundaries, [001] orientations and small Taylor factor were generated in the thermomechanical processes. Meanwhile, the special boundaries broke the random boundary network. Therefore, the material was able to achieve greater plastic deformation. Moreover, the mechanism of torsion and annealing on the plasticity of pure nickel was illustrated, which provides theoretical guidance for the pre-plasticization of nickel workpieces.

Microband-To-Microshear Band Transition near Grain Boundaries in BCC Steel

2007 ◽  
Vol 558-559 ◽  
pp. 873-878 ◽  
Author(s):  
Dorothée Dorner ◽  
Yoshitaka Adachi ◽  
Kaneaki Tsuzaki
Keyword(s):  
Grain Boundary ◽  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Compression Tests ◽  
Grain Boundary Characteristics ◽  
Band Transition ◽  
Boundary Characteristics ◽  
Backscatter Diffraction ◽  
Initial Crystal

Compression tests were performed on Fe-3%Si specimens with few grains. The deformation microstructure and microtexture were investigated by electron backscatter diffraction (EBSD) and related to the initial crystal orientation and grain boundary characteristics. Groups of microbands were found that are characterised by a periodic change in crystal orientation, shear at the grain boundary, and the formation of new grains. It is supposed that these microband groups represent an early stage of microshear band development.

scholarly journals The Effects of Strain Annealing on Grain Boundary Distribution and Hardening in Superpure Nickel

1996 ◽  
Vol 28 (1-2) ◽  
pp. 71-79 ◽  
Author(s):  
C. B. Thomson ◽  
V. Randle
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Pure Nickel ◽  
Special Boundary ◽  
Special Boundaries ◽  
Commercially Pure ◽  
Electron Backscatter ◽  
Twin Formation ◽  
High Level ◽  
Backscatter Diffraction

Electron backscatter diffraction is applied to the study of texture and mesotexture in superpure nickel. Low level strain annealing is shown to influence the grain boundary population such that greater proportions of special boundaries exist. It is found that variations in the texture of a specimen are not reflected by characteristic changes in the grain boundary population, indicating that texture analysis cannot be applied to the prediction of special boundary densities. Mechanisms active during the evolution of special boundaries are discussed and compared to those involved under similar conditions in commercially pure nickel. It is shown that alnnealing twin formation need not be prevalent for a high level of special boundaries to form. Differences in the hardness of various boundary types are identified, such that low angle boundaries and ∑3 boundaries close to exact misorientation can be categorized separately to other boundaries, in that they show minimal hardening.

A new insight into the ∑=2 grain boundary characteristics in WC powder and in WC-Co sintered materials

2018 ◽  
Vol 155 ◽  
pp. 372-378 ◽  
Author(s):  
Maxime Pellan ◽  
Sabine Lay ◽  
Jean-Michel Missiaen ◽  
Susanne Norgren ◽  
Jenny Angseryd ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundary Characteristics ◽  
Boundary Characteristics ◽  
Insight Into ◽  
Sintered Materials

Effect of Grain Boundary Characteristics on Lattice Orientations

2007 ◽  
Vol 26-28 ◽  
pp. 1003-1006 ◽  
Author(s):  
Jae Hyung Cho
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Microstructural Characterization ◽  
Grain Boundary Character Distribution ◽  
Average Scheme ◽  
Plane Normal ◽  
Grain Boundary Characteristics ◽  
Correlation Parameters ◽  
Boundary Characteristics

Grain boundary characteristics are defined by five parameter, grain boundary plane normal and misorientation angle/axis between two adjacent grains. The influence of the grain boundary character distribution on lattice evolution during deformation was investigated using three-dimensional crystal plasticity finite element method (CPFEM). Various combinations of grain boundaries were modeled systematically. In analyzing the numerical microstructural characterization obtained by the simulation, orientation average scheme and correlation parameters between misorientation and its special distribution are used. Inter- and intra-grain structures were investigated using the spatial distribution of lattice orientation. Main emphasis was placed on misorientation distributions around grain boundaries, where grain interaction mainly occurred.

Microstructure Evolution and Grain Boundary Characteristics of Oriented Silicon Steel during Primary Recrystallization in a Pulsed Magnetic Field

2013 ◽  
Vol 690-693 ◽  
pp. 139-146 ◽  
Author(s):  
Li Hua Liu ◽  
Li Juan Li ◽  
Qi Jie Zhai
Keyword(s):  
Magnetic Field ◽  
Grain Size ◽  
Magnetic Fields ◽  
Grain Boundary ◽  
Microstructure Evolution ◽  
Silicon Steel ◽  
Pulsed Magnetic Field ◽  
Magnetic Annealing ◽  
Grain Boundary Characteristics ◽  
Boundary Characteristics

The effects of a 2 T pulsed magnetic field primary annealing process on microstructure evolution and grain boundary characteristics in two-stage cold-rolled silicon steel were examined. Pulsed magnetic annealing increased grain size through the application of relatively smaller intensity of magnetic fields (2 T), compared to steady magnetic annealing. The effect of increasing grain size may be attributed to the magnetic acceleration effect of boundary motion under magnetic pulse conditions. Pulsed magnetic annealing may serve to enhance the relative intensity of the {111} component and decrease the frequency of low-angle misorientations. Repeated magnetostriction induced by pulsed magnetic field applications may accelerate overall dislocation motion. These findings suggest that pulsed magnetic fields require relatively lower intensities than steady magnetic fields to achieve superior results, providing a potentially viable alternative for industrial annealing processes for electrical steels.

Iron-clad MgB2Superconductor Wires

2001 ◽  
Vol 689 ◽  
Author(s):  
S. Jin ◽  
H. Mavoori ◽  
C. Bower ◽  
R. B. van Dover
Keyword(s):  
Grain Boundary ◽  
Critical Current ◽  
Practical Method ◽  
Processing Parameters ◽  
Composite Wire ◽  
Grain Boundary Characteristics ◽  
Boundary Characteristics

ABSTRACTThe fabrication of bulk, stoichiometric MgB2wires is a challenge because of the difficulties associated with the volatility and reactivity of magnesium and the brittleness of MgB2. Metal-clad processing of MgB2is a convenient, practical method of overcoming these problems. With such a fabrication approach, iron-clad MgB2superconductor wires exhibiting desirable characteristics with the transport Jcof ∼105 A/cm2at 4.2K have been obtained. In this paper, understanding of the composite wire structures, effect of processing parameters, grain boundary characteristics, and critical current bahavior of the MgB2wires will be described.

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