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The strongly grain size dependent work hardening behaviour at room temperature is shown to arise from both the grain size dependence of the dislocation storage as well as the grain size dependence of twinning.
The Consid`ere criterion is also shown (dashed line), the numbers refer to the first column in Table 2.
In the case of the fine grained material, twins were observed at higher strains but only in a fraction of the grains.
These numbers appear to be in good qualitative agreement with the TEM observations described above.
The predictions for the intermediate grain sizes is less good than at the coarse and fine grain limits.

The number of intermittent baseline cycles between consecutive overloads was varied (n=100 and n=10.000).
The influences of grain dimensions and number of intermittent baseline cycles on these effects were studied in the test program.
The overload tests were carried out with the two different numbers of intermittent baseline cycles n=100 and n=10.000.
Depending on the grain dimensions and the number of intermittent baseline cycles between the consecutive overloads, acceleration or retardation of crack propagation occurred compared to constant amplitude loading (Fig 2a and 2b).
The impact on crack propagation rate depends on the grain dimension, the slip distribution at constant amplitude, and number of intermittent baseline cycles between the consecutive overloads.

The forged component was longitudinally sectioned in the centre and thirty samples (10 × 10 × 10 mm) were cut from it and numbered sequentially (No. 1 to 30).
A large number of dynamically recrystallised (DRXed) grains (about 3-5 μm) are present in the microstructure (blue colour), with some coarse grains (red and yellow colour) distributed among them.
The overall distributions of grain size at various locations of the powder billet were acquired with a1 μm observation interval of the grain size.
The samples have a mean linear intercept grain size of 4.4-5.2 μm, and the standard deviation of the grain size distribution is 2.6-3.0.
Moreover, relative frequency of grain size greater than 5 μm decreases as grain size increases, indicating that there was little chance for the recrystallised grains to grow during the deformation process.

It is proved that an increase in the pre-pressure on the parent powder mixture reduces the grain size, and an increase in the delay time increases the grain size in the synthesized intermetallic compound.
Reduction of the grain size in the pressure-synthesized intermetallide when increasing the pre-pressure on the parent powder mixture is due to an increased number of contacts of dissimilar particles in the powder mixture.
These particles determine the number of nuclei generating the intermetallic compound and in the process of crystallization of the high-temperature synthesis product, the number of grains in the emerging polycrystalline structure.
These parameters determine the grain size in the synthesized intermetallic compound polycrystalline structure.
Changes in grain size have a significant effect on the strength of the synthesized intermetallic compound.

Harmonic structure (HS) is a structure in which the ultrafine grain (UFG) structure (Shell) covers the coarse grain (CG) structure (Core) and the fine grains are interconnected in a network.
Grain Orientation Spread (GOS) analysis by EBSD was performed to evaluate the misorientation of the grains.
That is, a grain with a higher GOS value contains a large number of dislocations.
The GOS value is represented as follows; For a grain i, the GOS is GOSi=1J(i)jωij (1) Where J(i) is the number of pixels of the grain i and ωij the misorientation angle between the orientation of pixel j and the mean orientation of grain i [4].
Acknowledgement This work was supported by JSPS KAKENHI Grant Number JP18H05256 and 18H05455.

To develop superplastic materials, small grain (usually < 10 μm) [1] is an important prerequisite because the superplasticity occurs through sliding of mutual grains at grain boundaries [2].
Here, we adopted the HPT process for an Al 7075 alloy to produce fine grains and then to investigate the superplastic behavior.
Microhardness increases with increasing distance from the disk center for all numbers but the hardness saturates to a constant level.
This study clearly demonstrated that high strain rate and low temperature superplasticity was attained through grain refinement of an Al 7075 alloy when the grain size was refined by HPT processing.
Shin, Low-temperature superplastic behavior of a submicrometer-grained 5083 Al alloy fabricated by severe plastic deformation, Metall.

These reactions are driven by the local stresses in the grain boundaries, presumably much higher in magnitude and dispersion than those in the grain interiors.
Since the homogenization scheme does not provide local information on and hence, the resulting RSS values on the variants, it was assumed that the RSS values at the grain boundaries can be estimated by adding a local fluctuation term to those obtained by projecting the grain average stress tensor on the variants i.e. where is the RSS on the variant using the grain average stress (obtained by VPSC), r is a random number between 0 and 1, is the fluctuation term and is the estimate of the RSS on the variant at the grain boundary.
In each grain, the inner 6 x 6 x 6 block of voxels was considered as part of the grain interior and the layer of voxels close to the grain boundary as the grain boundary zone (Figure 1c).
Figure 1: a) (0001)basal pole figure of the initial texture of pure Mg; b) 3D polycrystal with cuboidal grains used in the FFT calculations; c) 2D schematic showing the “grain interior” and the “grain boundary” zone in one grain.
The results show that the average RSS is basically the same for interior and grain boundary zones and, as expected, the dispersion in the grain boundary zone is generally higher compared to the grain interior zone.

Introduction Equal channel angular pressing (ECAP) is the representative technique of severe plastic deformation refining the grain size of metallic materials down to the submicrometer level, so called ultrafine grained (UFG) materials.
In addition to a near-equiaxed UFG structure, high angle grain boundaries are another necessary condition to achieve LTS.
The combined process of ECAP and conventional cold rolling is anticipated not only to reduce the number of ECAP passage but also to fabricate UFG sheets or plates.
There was no significant difference in the apparent (sub)grain size between the two samples, ~ 0.3 �.
The band width was comparable to the (sub)grain or cell size of the ECAP sample.

During the past few decades, A Large number of research on engineering characteristics of coarse-grained soil have been carried out by many scholars abroad, and have obtained certain achievements[2-12].
Then, fine particles of coarse-grained soil fully fill into the pore between the large particles of coarse-grained soil.
In-situ compaction of coarse-grained materials[M].
Characteristic of dilatation of several kinds of grained soils[J].
Engineering properties and applications of coarse grained soil[J].

Kirkendall Effect During Grain Boundary Interdiffusion in Polycrystalline Thin Films Leonid Klinger, Eugen Rabkin Department of Materials Engineering, Technion – Israel Institute of Technology, 32000 Haifa, Israel klinger@tx.technion.ac.il, erabkin@tx.technion.ac.il Keywords: thin films; grain boundaries; stress relaxation; Kirkendall effect; interdiffusion Abstract We consider the kinetics of chemical interdiffusion along the grain boundaries in stressed thin metal film attached to inert substrate.
Grain boundary (GB) self-diffusion of the film atoms is an important mechanism of stress relaxation in unpassivated films.
For simplicity, we will consider a quasi one-dimensional film, with the stripe-like grains of width L.
This is because for DBnumber of A-atoms leaving the film is larger than the number of B-atoms penetrating into the film, especially for the short annealing times for which the concentration gradients driving chemical interdiffusion are high.
Kaur I, Mishin Y, Gust W (1995) Fundamentals of grain and interphase boundary diffusion, Wiley, Chichester, UK