Analysis of Dynamic Grain Growth Behavior during Superplastic Deformation Using a Grain Boundary Diffusion Mechanism

AbstractSuperplastic tensile deformation is simulated in 2 dimensions by incorporating grain boundary diffusion and concurrent grain growth derived from static and dynamic growth mechanisms. The following relationship is found between microstructural changes and deformation behavior for constant stress conditions. Grain boundary diffusion produces an increase in the aspect ratio of the matrix grains during deformation and the increased aspect ratio causes a change in creep rate parameters: the stress exponent is decreased from the initial value of 1.0 for equiaxed grains and the grain size exponent is increased from the initial value of 3.0. Accelerated grain growth is also found by the present simulation.

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Void Growth Behavior in ULSI Cu Interconnections by Grain-Boundary Diffusion Simulation

Journal of Electronic Materials ◽

10.1007/s11664-010-1311-4 ◽

2010 ◽

Vol 39 (10) ◽

pp. 2255-2266

Author(s):

Takashi Onishi ◽

Masao Mizuno ◽

Tetsuya Yoshikawa ◽

Jun Munemasa ◽

Takao Inoue ◽

...

Keyword(s):

Grain Boundary ◽

Void Growth ◽

Boundary Diffusion ◽

Growth Behavior ◽

Grain Boundary Diffusion ◽

Diffusion Simulation

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Nd-Fe-B Magnets: The Gradient Change of Microstructures and the Diffusion Principle after Grain Boundary Diffusion Process

Materials ◽

10.3390/ma12233881 ◽

2019 ◽

Vol 12 (23) ◽

pp. 3881 ◽

Cited By ~ 1

Author(s):

Yaojun Lu ◽

Shuwei Zhong ◽

Munan Yang ◽

Chunming Wang ◽

Liuyimei Yang ◽

...

Keyword(s):

Surface Layer ◽

Grain Boundary ◽

Diffusion Process ◽

Shell Structure ◽

Boundary Diffusion ◽

Diffusion Mechanism ◽

Temperature Stability ◽

Grain Boundary Diffusion ◽

Core Shell ◽

Core Shell Structure

The diffusion of Tb in sintered Nd-Fe-B magnets by the grain boundary diffusion process can significantly enhance coercivity. However, due to the influence of microstructures at different depths, the coercivity increment and temperature stability gradually decreases with the increase of diffusion depth, and exhibit good corrosion resistance at a sub-surface layer (300–1000 μm). According to the Electron Probe Micro-analyzer (EPMA) test results and the diffusion mechanism, the grain boundary and intragranular diffusion behavior under different Tb concentration gradients were analyzed, and the diffusion was divided into three stages. The first stage is located on the surface of the magnet, which formed a thick core-shell structure and a large number of RE-rich phases. The second stage is located in the sub-surface layer, forming a uniform and continuous RE-rich phase and thin core-shell structure. The third stage is located deeper in the magnet, and the Tb enrichment only existed at the triangular grain boundary.

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Diffusion and solubility of holmium ions in barium titanate ceramics

Journal of Materials Research ◽

10.1557/jmr.2004.0466 ◽

2004 ◽

Vol 19 (12) ◽

pp. 3512-3520 ◽

Cited By ~ 14

Author(s):

Junichi Itoh ◽

Hajime Haneda ◽

Shunichi Hishita ◽

Isao Sakaguchi ◽

Naoki Ohashi ◽

...

Keyword(s):

Barium Titanate ◽

Grain Boundary ◽

Diffusion Coefficients ◽

Boundary Diffusion ◽

Diffusion Mechanism ◽

Annealed Sample ◽

Lattice Diffusion ◽

Grain Boundary Diffusion ◽

A Site ◽

Titanate Ceramics

Ho ion solubility and diffusivity were evaluated in barium titanate ceramics in which Ho ions were implanted with an accelerating voltage of 500 keV. The depth profile of the ions was composed of three regions in the post-annealed sample: the first was the precipitation region, the second was a region created by lattice diffusion of Ho ions, and the third was a region created by grain-boundary diffusion. The Ho lattice diffusion characteristics were similar to those of Ni ion diffusion in barium titanate ceramics, and we concluded that the diffusion mechanism was the same as that responsible for Ni ions. The Ho ions diffused through the B-site (Ti-site) and were then exchanged with A-site ions. This mechanism suggests that a small number of Ho ions dissolved in the B-site. Preferential grain-boundary diffusion was also observed. The grain-boundary diffusion coefficients were four to five orders of magnitude larger than the volume diffusion coefficients. The solubility of Ho ions was estimated to be a few thousand parts per million in barium titanate ceramics.

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Diffusion Mechanisms in Nanocrystalline and Nanolaminated Au-Cu

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.266.13 ◽

2007 ◽

Vol 266 ◽

pp. 13-28 ◽

Cited By ~ 8

Author(s):

Alan F. Jankowski

Keyword(s):

Low Temperature ◽

Grain Boundary ◽

Grain Growth ◽

Boundary Diffusion ◽

Bulk Diffusion ◽

Grain Boundary Diffusion ◽

Dominant Mechanism ◽

Temperature Range ◽

Diffusion Mechanisms ◽

Kinetics Of

Thermal anneal treatments are used to identify the temperature range of the two dominant diffusion mechanisms – bulk and grain boundary. To assess the transition between mechanisms, the low temperature range for bulk diffusion is established utilizing the decay of static concentration waves in composition-modulated nanolaminates. These multilayered structures are synthesized using vapor deposition methods as thermal evaporation and magnetron sputtering. However, at low temperature the kinetics of grain-boundary diffusion are much faster than bulk diffusion. The synthesis of Au-Cu alloys (0-20 wt.% Cu) with grain sizes as small as 5 nm is accomplished using pulsed electro-deposition. Since the nanocrystalline grain structure is thermally unstable, these structures are ideal for measuring the kinetics of grain boundary diffusion as measured by coarsening of grain size with low temperature anneal treatments. A transition in the dominant mechanism for grain growth from grain boundary to bulk diffusion is found with an increase in temperature. The activation energy for bulk diffusion is found to be 1.8 eV·atom-1 whereas that for grain growth at low temperatures is only 0.2 eV·atom-1. The temperature for transitioning from the dominant mechanism of grain boundary to bulk diffusion is found to be 57% of the alloy melt temperature and is dependent on composition.

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