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The grain boundary sliding and the formation of slipped bands and cavitations during biaxial tensile deformation were examined in fine grained Al-Mg alloy.
It was found that at the same equivalent strain conditions, the number of cavities under biaxial tension is significantly greater than that under uniaxial tension.
Voids and grain boundary sliding at the grain boundaries normal to the tensile direction as well as fibrous structures can be confirmed.
Dynamic recrystallization and grain growth are considered to contribute to the above, since the amounts of rotation of crystal grains and grain boundary sliding are large under uniaxial stress.
The scratches are bent in undulations at grain boundaries, but straight inside grains, and their inclinations are varied at grain boundaries.

The relation between the relative standard deviation of grain size and the ratio of twin number to grain number is obtained.
Fig.1 shows the influence of the ratio of twin number to grain number on the relative standard deviation.
The relation between the relative standard deviation and ratio of twin number to grain numbers of microstructures shown in Fig.4 are described in Fig.5.
The twins have obvious effect to grain growth inhibition, the mechanism is that the formed twins increase the mobility viscosity of 30 35 40 45 50 55 60 65 70 0.20 0.25 0.30 0.35 0.40 0.45 0.50 Relative Standard Deviation Ratio of Twins and Grains Number (%) Fig. 1 The influence of Al2O3 content on standard deviations.
Fig. 5 The relation curve between relative standard deviation and ratio of twin number to grain number of microstructures described in Fig.4.

With the social and economic development of our country, in particular, a number of large-scale hydraulic and hydropower projects to be built during the development of the western region, as a type of filling material, rockfill material will be more widely used in the high rockfill works [1].
Characteristic of grain breakage Measurement of grain breakage.
This indicates that the vibration process during sample preparation mainly cause breakage of large-sized grains to increase the proportion of fine grains; despite the small amount breakage of medium-sized grains, the breakage of large-sized grains may supplement these decreased medium-sized grains.
Grain breakage caused by triaxial test.
(3) During the shearing process, the breakage of grains in rockfill materials mainly occurs on the surface of grains with diameter between 20~60 mm, and most grains break into fine grains with diameter under 10mm.

Details such as misorientation angle, inclination angle, GB plane, CSL value (∑), simulation box size and number of atoms are mentioned in table 1 and table 2 for STGB and ATGBs respectively.
Tilt axis GB plane (hkl) Sigma (∑) Misorientation angle (θ) Simulation Box dimensions Number of atoms 1. <110> <111> ∑3 70.53° 66.16x265x99.24 97,636 Table 2 Configuration details for four ∑3 asymmetric tilt grain boundary tilted along <110> with θ=70.53°.
Inclination angle (Φ) GB plane(s) (hkl)1/(hkl)2 Simulation box dimensions Number of atoms 1. 15.79° <221>/<447> 65x330.8x99.24 1,19,848 2. 29.50° <11 14>/<332> 68.3x264.8x99.24 1,00,532 3. 54.74° <221>/<001> 65x272x99.24 1,00,702 4. 76.74° <445>/<227> 66.4x265x99.24 97,847 Results and Discussion Asymmetric tilt grain boudaries were generated in LAMMPS using the methodology described in Fig. 1.
Fig.1 Schematic for generating asymmetric tilt grain boundary.
Ab initio calculations of grain boundaries in bcc metals.

Cooperative Grain Boundary Sliding and Shear Banding at High Strains in Ultrafine Grained and Nanocrystalline Pd Alloys.
In cg specimen a grain refinement occurs whereas in nc one – the grain growth. 4.
These in-grain accommodation processes occur in non-correlated manner in adjacent grains leading to formation of cracks and voids in sliding grain boundaries.
Secondly, a number of grains retarding the band formation experience intragranular slip [19-21].
Vol. 18 (1983), p. 582 ], which is necessary to form enough number of CGBS bands to maintain steady plastic flow [[] A.I.

The experimental results show that, grain number per unit area of DIF increases with decreasing deformation temperature or increasing deformation amount; the grain size of DIF is not very sensitive to the deformation conditions; the volume fraction of DIF increases due to the increased grain number per unit area.
The curves of the volume fraction, grain number per unit area and mean grain diameter of DIF vs deformation temperature are illustrated in Fig.2.
The grain number per unit area will increases with nucleation rate of DIF.
The curves of the volume fraction, average grain diameter and grain number per unit area of DIF vs deformation amount are illustrated in Fig.4.
As the deformation amount increases, the grain number per unit area of DIF increases, with the nucleation site transitioning from grain boundaries to deformation bands inside the grains.

The solute segregation to grain boundaries may be classified into equilibrium and non-equilibrium segregation.
Introduction Material grain boundaries comprise of narrow zones of weakness.
When failure occurs in material, it often occurs catastrophically by fracture along grain boundaries and often by the micro-segregation of embrittling impurity to these grain-boundaries.
Data group number M input Data of group i input Atom percent of each element calculation and output Withdraw from the system Average atom per cent calculation and output Are the data right?
McLean, Grain-Boundaries in Metals, Oxford University Press, UK (1957)

The grain boundary radius, Rd, and the virtual grain radius, R, are equal respectively to the average grain boundary radius and the average grain radius in the polycrystal.
This number of particles is much higher than the Zener estimate for a rigid boundary.
In this case, nmin would be equal to 11 particles, roughly half the number of particles in contact obtained by the simulation.
A large number of simulations have been performed for a wide variety of conditions (particle radii, volume fractions and driving forces) to determine the typical numbers of particles in contact with the boundary at pinning compared with the standard Zener values nmin and nrandom.
Journal Title and Volume Number (to be inserted by the publisher) 9 Grain size at complete pinning was simulated for two other particle sizes: Rp = 0.075Rd(0), Rp = 0.15Rd(0).

Beijing Aeronautical Manufacturing Technology Research Institute and Central South University have carried out large numbers of investigations against the preparation of superplastic fine-grained sheets and the superplasticity of fine-grained 1420 Al-Li alloy together.
But the grain size has been grown slightly compared to as-received material.
A large number of dislocations were existed in deformed material and these dislocations came from the second phase and grain boundary especially triple point (Fig.7).
Dislocation would glide and climb near grain boundary during deformation, which contributed to grain boundary slipping.
(a) δ′ phase in grain (b) δ′ phase in grain boundary Fig.6 The second-phase of fine-grained 1420 after superplastic deformation (a) Dislocation near grain boundary (b) Dislocation around the second phase Fig.7 Dislocation morphology after superplastic deformation Conclusions Fine-grained 1420 Al-Li alloy which prepared by two-stage aging and turning rolling process exhibited good superplasticity.

In all cases mesoscopic grain/interphase boundary sliding (~ grain diameter or more) is suggested to be the rate controlling mechanism [1–3].
A high–angle grain boundary is divided into a number of atomic scale ensembles that surround free volume sites present at discrete locations characteristic of the boundary.
The grain shape is assumed to be rhombic dodecahedron.
The average grain size is L.
The grain sizes in all but one system are in the sub-micron range.