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AlTiC grain refiners form a relatively new alternative to the existing class of AlTiB grain refiners for achieving fine equiaxed grain structure in aluminum alloys during casting and solidification.
Furthermore, commercial Al-5Ti-B grain refiner was also added to A3003 alloy to compare grain refinement ability with Al-Ti-C grain refiner fabricated in the present study.
The Al-Ti-B grain refiner produced some grain refinement too, but the refinement started at relative longer holding time than that from the Al-Ti-C grain refiner.
Fig. 3 Grain size measurement result of A3003 alloy unrefined, refined through the addition of Al-Ti-B refiner and Al-Ti-C refiner Two conditions need to be fulfilled to obtain efficient grain refinement: (i) a sufficient number of potential nuclei must be present in the melt and (ii) a large fraction of potential nuclei must be activated.
TiAl3 is known to have more number of planes that have good orientation relationship with aluminium in comparison to TiC or TiB2.

This can be taken from fig.2 for a number of ELC and CMn steels.
Ferrite grain sizes are estimated an ASTM number well above the scale of 10.
As demonstrated in fig.3, these ferrite grains connect with a layer of ultra fine ferrite grains.
The abnormal grain growth seems to initiate at the interface between larger ferrite grains below the strip surface and the ultra fine-grained ferrite layer developed at some distance below the strip surface.
Second, the presence of deformed or even static recrystallised ferrite grains at the interface with the fine-grained ferrite layer.

The recombination activity of grain boundaries has been shown to depend on their impurity gettering ability, the property which depends on the grain boundary structure [2].
Small Angle (SA) grain boundaries, also called Sub-Grain Boundaries (sub-GBs) adjoin grains with small crystallographic misorientation, typically less than [7].
Results and Discussion Figure 1 show the microstructure of near sub-GB dislocations, in two ingot positions namely wafer number 551 and 559, approximately 2.5 mm apart.
(a) is from wafer number 551, 8 wafers below (b) .
The dislocations are localized near the sub-GB and the density of dislocations has increased from wafer number 551 to 559.

While majority of the fragmented grains are ≤ 30 nm in size, almost equal number of grains measure ~ 20, 50 and 60 nm.
Contrast in high resolution images arises out of a complex interference of the direct beam and a number of the diffracted beams, the phase part of which is lost in the image.
The other term is sensitive to the projected potential of the atoms present in the material and number of atoms in each column under consideration.
As Ti is alloyed with Ta and Nb, their presence in the column and/or local change in thickness which will in turn change the number of atoms in each column may lead to such kind of variation in the contrast in the image.
Although extensive grain refinement takes place, all the grains do not fragment equally due to the variation in orientation of the grains.

Introduction In a number of recent publications (see, for example, [1-3]), it is shown that grain boundaries in metallic micro- and nanocrystalline materials obtained by severe plastic deformation substantially differ from that in ordinary polycrystals of recrystallized origin.
In [5-7 et al.] this method was successfully applied to study grain boundaries in a number of polycrystalline transition and noble metals.
The same is demonstrated by electron diffraction patterns (Fig. 1b) in which a great number of point reflections are located on the Debye rings, which means that the grains are high-angle.
Grain boundaries are still strongly curved, and dislocation density in the grains is high.
Figures 1 and 2 denote the spectrum component numbers.

New experimental data related to the grain size and the Bauschinger effects have been obtained for ferritic steels with grain size in the range of 3.5-22µm.
The consequences are discussed for fine grain metallic alloys.
As the back-stress σb is assumed to be mainly due the dislocation pile-ups against the grain boundaries, it can be expressed in a simple form as : b M b n D µ σ = , (5) where D is the grain size and n the mean number of the dislocations in a pile-up.
The ratio λ/b gives the number of dislocations per slip band geometrically necessary to provide the deformation and the corrective term (1-n/n0) accounts for the finite number of sites available for dislocations at the grain boundary.
Conclusion New experimental data related to the effect of grain size and the Bauschinger effect have been obtained for ferritic steels with grain size in the range of 3.5-22µm.

Firstly, Mg deforms by a limited number of slip and twin systems and secondly Mg develops strong textures during processing [1].
Twinning is highly sensitive to grain size [2], with finer grain sized samples exhibiting a lower volume fraction of twins.
There have been a number of studies that aim to reduce the grain size of magnesium below the values produced by conventional processing.
After hot rolling, a number of annealing treatments were carried between 150°C and 350°C.
This resulted in a grain size of 2.2µm, Figure. 2b.

(a) Image Quality (IQ) map showing the columnar layer of grains and (b) boundary map showing the grain morphology on the normal plane.
A number of reasons may be hold responsible for the closing error problem.
Results and discussion Relative grain boundary energy.
Grain boundary character distribution.
An approximate number of 100 and 200 boundaries were analyzed in the electrolytic Fe and Fe-Si sample respectively.

The most notable property of grain boundary engineered materials is the increased number of special boundaries in the material [2].
The CSL theory designates the misorientation based on the inverse of the number of overlapping lattice sites [3].
To characterize the connectivity, triple junctions are classified based on the number of special versus the number of random boundaries at the junction.
However, after a certain number of cycles or too large a strain, the special boundary fraction actually begins to decrease [9].
Acknowledgements The work was supported primarily by a Materials World Network grant from the National Science Foundation under the Award Number DMR-1107896.

Parameters of the Fe diffusion Matrix A§ Em (eV/atom) liquid Al95Fe05 7.4·10-7 0.47 liquid Al90Fe10 4.4·10-6 0.63 liquid Al80Fe20 2.7·10-4 1.01 <100> S5 non-symmetric GB in impure Al 1.7·10-15 0.61 <100> S5 symmetric GB in impure Al 2.9·10-14 0.82 <111> S7 symmetric GB in impure Al 7.7·10-12 1.28 The grain boundary diffusion was determined as follows: , (1) where W is the atomic volume, A is the grain boundary area and d is the grain boundary width, NGB is the number of atoms in the GB region and Dxi and Dyi are displacements of atom I in the GB plane.
Fe-Fe coordination number in liquid Al-Fe alloys and in GBs.
Indeed, as can be seen from Fig. 4 the Fe-Fe coordination number reaches some limit which ranges from 3.0 to 3.6 depending on the average Fe concentration.
Rodin: "Grain Boundary Diffusion and Grain Boundary Segregation" In Proc.
In: The Nature and Behavior of Grain Boundaries, H.