Atomistic Simulation of Cooperative Grain Boundary Sliding in Two-Dimensional Polycrystal

Surface microstructure of nano-composite ceramics prepared by mixed coherence system and machined by two-dimensional ultrasonic precision grinding was researched using TEM, SEM, XRD detector and other equipments. Structure, formation mechanism and characteristic of metamorphic layer of ground surface of nano-composite ceramics were researched. The experiment shows micro deformation mechanism of ceramic material in two-dimensional ultrasound grinding is twin grain boundary and grain-boundary sliding for Al2O3, and it is crystal dislocation of enhanced phase, matrix grain boundary sliding, coordination deformation of intergranular second phase as well as its deformation mechanism for nano-composite ceramics. The fracture surfaces of nano-composite materials with different microscopic structure were observed using TEM and SEM. Research shows that ZrO2 plays an important influence on the generation and expansion of crack, and enhances the strength of grain boundaries. When grain boundaries is rich in the ZrO2 particles, the crack produced in grinding process will be prevented, and the surface with plastic deformation will be smooth. The results shows nanoparticles dispersed in grain boundary prevents crack propagation and makes materials fracture transgranularly which makes the processed surface fine.

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Direct Observation of Two-Dimensional Grain Boundary Sliding and Switching in ODS Ferritic Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.838-839.43 ◽

2016 ◽

Vol 838-839 ◽

pp. 43-50

Author(s):

Eiichi Sato ◽

Hiroshi Masuda ◽

Yoshito Sugino ◽

Shigeharu Ukai

Keyword(s):

Grain Boundary ◽

Ferritic Steel ◽

Tensile Deformation ◽

Grain Boundary Sliding ◽

Grain Structure ◽

Two Dimensional ◽

Kernel Average Misorientation ◽

Boundary Sliding ◽

High Temperature Tensile ◽

Region Ii

High-temperature tensile deformation was performed using an oxide-dispersionstrengthened (ODS) ferritic steel,, which has grain structure largely elongated and aligned in one direction, in the perpendicular direction. In the superplastic region II, two-dimensional grain boundary sliding (GBS) was achieved, in which the material did not shrink in the grain-axis direction and grain-boundary steps appeared only in the surface perpendicular to the grain axis. In this condition, a classical grain switching event was observed. Using kernel average misorientation maps drawn with SEM/EBSD, dominant deformation mechanisms and accommodation processes for GBS were examined in the different regions. Cooperative grain boundary sliding, in which only some of grain boundaries slide, was also observed.

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Research on Surface Microstructures of Nanocomposite Ceramics in Two-Dimensional Ultrasonic Ultraprecision Grinding

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.364-366.909 ◽

2007 ◽

Vol 364-366 ◽

pp. 909-913 ◽

Cited By ~ 2

Author(s):

Bo Zhao ◽

Jing Lin Tong ◽

Yan Wu ◽

Guo Fu Gao

Keyword(s):

Grain Boundary ◽

Deformation Mechanism ◽

Grain Boundary Sliding ◽

Nano Particles ◽

Surface Generation ◽

Second Phase ◽

Two Dimensional ◽

Boundary Sliding ◽

Microscopic Deformation ◽

Surface Microstructures

Using TEM, SEM and XRD, the surface microstructures of nanocomposite ceramics prepared by heterocoagulation was studied in two-dimensional ultraprecision grinding with ultrasonic assistance. This research was focused on the structure of ground surface degenerating layer, surface generation mechanism and characteristics of nanocomposite ceramic parts. The experimental results showed that the microscopic deformation mechanism of the ordinary Al2O3 parts was grain- boundary twinning and grain-boundary sliding while microscopic deformation mechanism of nanophase ceramic parts was the inner crystal dislocation of strengthened phase with intragranular structure. And its deformation coordination mechanisms were the grain-boundary sliding and coordination deformation of intercrystalline second-phase. The observation on the fracture surfaces of nanocomposite materials with different microscopic structures by TEM and SEM showed that ZrO2 particles had an important effect on the generation and expansion of crack in ceramic parts. The introduction of ZrO2 particles strengthened the interface intensity of grain boundary. If there were rich ZrO2 particles on the grain boundary, the cracks generated during the grinding process would be prevented. Smooth and plastic deformation processing surface was obtained. It was proved further that the nanophase materials behaved transcrystalline fracture due to the nano particles, dispersed in the grain boundary and prevented the expansion of crack. This material’s fracture behavior made favorable surface possible. In the precise grinding of nano materials, the plastic removal mechanism dominated the process. The dislocated depth of the nanocomposite ceramics after grinding was bigger than that of common ceramics, which meant that dislocation increased.

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Mantle region accommodating two-dimensional grain boundary sliding in ODS ferritic steel

Philosophical Magazine Letters ◽

10.1080/09500839.2015.1067732 ◽

2015 ◽

Vol 95 (7) ◽

pp. 359-366 ◽

Cited By ~ 8

Author(s):

Hiroshi Masuda ◽

Hirobumi Tobe ◽

Eiichi Sato ◽

Yoshito Sugino ◽

Shigeharu Ukai

Keyword(s):

Grain Boundary ◽

Ferritic Steel ◽

Grain Boundary Sliding ◽

Two Dimensional ◽

Boundary Sliding

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Diffusion-Accommodated Grain Boundary Sliding in a Polycrystal

MRS Proceedings ◽

10.1557/proc-196-15 ◽

1990 ◽

Vol 196 ◽

Cited By ~ 1

Author(s):

P. M. Hazzledine ◽

J. H. Schneibel

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Grain Boundary Sliding ◽

Diffusional Creep ◽

Two Dimensional ◽

Dimensional Model ◽

Material Deposition ◽

Two Dimensional Model ◽

Boundary Sliding ◽

Coble Creep

ABSTRACTA two-dimensional model for diffusional creep (Coble creep) and diffusionaccommodated grain boundary sliding in polycrystals has been developed. The results obtained for small symmetrical clusters of grains reproduce Spingam and Nix's work [Acta Metall. 2M, 1389 (1978)]. For clusters of irregularly shaped grains the material deposition and removal rates, the fluxes along the grain boundaries, the grain boundary tractions as well as the grain boundary sliding rates are irregular and can all be calculated.

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