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Since the grain sizes vary with current density, the grain density defined as the average grain number per cm2, as a function of current density can be derived, as shown in Fig. 5.
Fig. 5 The average grain number per cm2 vs. current density curve.
According to Fig. 6(a), when applying ACP during liquid inoculation stage, the macrostructure is coarse columnar and equiaxed grains, the grain sizes are larger than that without ACP.
The grains are remarkably refined, and its grain sizes are almost no different from that applying ACP with density of 230 Acm-2 during the whole solidification process.
The grain is not refined compared with macrostructure without ACP.

One more factor of the particular importance for development of the superplastic flow is the total area of grain boundaries, growing with refinement of grains.
For the quantitative estimation of the grain fraction, giving an input into the deformation of material by means of intergranular glide, a number of parameters are calculated by direct texture pole figures.
If p=1 in the point of PF(0001) with angular coordinates (ψ, φ), it signifies that in the studied sample the relative number of grains with the corresponding orientation of basal axis is the same as in the textureless sample.
At that, value p shows, by how many times the number of grains with the corresponding orientation of basal axis is higher or lower, than in the absence of texture.
New finest nuclei of α-grains form and “go away” from β-grains, giving rise to them, by means of the slip by interphase boundary.

Andersson et al. [9] indicated that Nd 3+/Sm3+ or Pr 3+/Gd3+ co-doped ceria which had an effective atomic number between 61 (Pm) and 62 (Sm) should possess the highest electrical conductivity, and experimental evidences soundly supported the result [4, 10].
The conductivities are measured using ac impedance spectroscopy due to it is possible to study the separate contributions from the grain and the grain boundary to the overall ionic conductivity.
As it is known that the grain size is almost the same for all the SNDC samples with various thicknesses, the number of the grain layers decreases with the decrease of the thickness.
The typical plots of ln(σT) versus 1000/T for the grain and the grain boundary conductivities of the SNDC electrolytes with various thicknesses are shown in Fig. 3 and 4.
They show that the grain conductivity values of all the SNDC samples with different thicknesses are almost same while the grain boundary conductivity increases with the decrease of the electrolyte thickness, which indicates that the enhancement of the total conductivity is not contributed to the grain conductivity but the increased grain boundary conductivity.

The Effect of Texture on the Fatigue Properties of Ultrafine-Grained Interstitial-Free Steel Thomas Niendorf1,a,† , Thorsten Marten 1,b, Hans J.
Despite the relevance of fatigue properties for many applications, only a limited number of studies is available that report on the fatigue properties of these materials.
For bcc and hcp materials only a very limited number of reports is available [15-17].
The IF steel was deformed using route E, a hybrid route with a rotation order of 180°/90°/180° within four passes, with a total number of eight passes.
equiaxed grains with similar grain sizes) and the local texture.

Effect of Surface and Grain Boundary on the Reversion of Al-Zn Alloys Keiyu Nakagawa1, a *and Teruto Kanadani1, b 1Okayama University of Science, 1-1 Kita-ku Ridai-cho Okayama, 700-0005, Japan anakagawa@mech.ous.ac.jp, bkanadani@mech.ous.ac.jp Keywords: Al-Zn alloys, Aging, Reversion, Grain boundary, Surface, Vacancy, GP zone Abstract.
Age-hardening of an Al-Zn alloy after quenching develops inhomogeneously due to the effect of surface as a vacancy sink and grain boundary as an easy path.
Grains were coarsened by the strain-annealing method to about 5mm in diameter.
Fig.2 shows variation of the isochronal curves in hardness at 0.49N of load with the position of indentation in the grain.
At several stages of the isothermal annealing, dependence of hardness number on the load of indentation was measured.

The average grain size of the ultrafine-grained surface layers (UF) is less than 2 µm, whereas the intermediate region (M) is medium-grained.
The grains in ultrafine-grained layers are elongated to the rolling direction.
For the case of the medium-grained material (M), the grain is almost equiaxial.
The number of grain size in the gage volume is about 5.6x104.
The number of measured points was 121.

Grain refiner intensifies the effect of UST, as a result the grain size appears to be additionally reduced.
Al-5Ti-1B decreases the grain size from 150 to 105 µm.
This effect can be a result of the influence of grain refiners and/or involving of larger numbers of grain refining particles into the solidification process.
In all cases grain size is about 130 µm.
Further treatment leads to grain size reduction to 130 µm.

Grinding test was carried out to study the grinding of granite with single diamond grain.
Forces were measured to investigate the mean normal and tangential forces acted on the diamond grain.
Fig. 1 Uniaxial compression test Fig. 2 Three-point bending test Fig. 3 Simulation of grinding G603 by single iamond grain Tab. 1 Basic parameters of granite specimen Category of granite G603 Density ρ (kg/m3) 2610 Posority n 0.19 friction coefficient f 0.4 Normal siffnesskn(N/m) 2.6×1015 Ration of stiffness kn/ks Fig. 5 Schematic diagram of single diamond grain grinding tester 1 Young’s modulus of elasticity Ec(Pa) 2.6×1010 Parallel bond modulus of elasticity (Pa) 2.6×1010 Compression strength (MPa) 176.5 Bending strength(MPa) 194.6 1.3 Result and analysis of 3-D DEM The 3-D DEM dynamic simulation process of single diamond grain grinding G603 in shown in Fig. 3, and damping coefficient=0.45, size of specimen is 1mm×0.3mm×0.4mm, number of particles are 60588, the cutting velocity ( Vs) is 5m/s, the cutting depth (ap) is 20 μm.
Along with the grain moved forward, more and more single particle or small particle group has been removed and accumulated in front of grain, the number of cracks increased gradually, so material were removed and scratch was formatted.
It can be seen from Fig. 6, diamond grain was keep intact which eliminate the influence factor that wear of diamond grain to the acted loads. 3.

ECAP resulted in significant grain refinement down to the sub micron level and corresponding increase in hardness.
Introduction There has been considerable interest in metals and alloys with an ultra fine grain (UFG) size (100nm to 1µm) as this significant grain refinement leads to considerable increases in tensile strength, hardness, corrosion and wear resistance in comparison to its coarse grained (CG) counterparts [1-6].
In a number of cases, the crack propagated at an angle to the principle stress axis, therefore finite element modelling (FEM) was employed to calculate stress intensity factor ranges.
This suggests that small grain size differences and differences in grain boundary character do not have a significant influence on fatigue crack growth behavior.
Large increases in Vickers Hardness follow from the significant levels of grain refinement.

These stages are connected with relaxation of the defects, migration of nonequilibrium grain boundaries and grain growth.
A mean grain size in the sample was obtained by averaging of more than 100 grains.
A number of SAED patterns from the small neighbouring areas 0.09 µm2 indicate the formation of grain boundaries (GBs) mainly of a high angle type (Fig. 1c).
This observation is in agreement with a great number of spots uniformly arranged in circles on SAED patterns from the larger square area 0.5 µm 2 (Fig. 1a).
Grains of about 1.5 µm size are formed within ultrafine grained "matrix" (20 - 30% of observed areas).