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During DIFT, the ferrite grain number per unit area increases continuously, but it decreases during continuous cooling 913K 953K 993K transformation or during isothermal transformation in a plain low carbon steel.
During this process, the ferrite grain numbers and the transformed volume fraction increase progressively.
Niobium in both the states is favorable for the DIF grain refinement.
Furthermore, it can be Number C Si Mn Nb V Ti N A 0.003 0.22 1.12 0.052 \ 0.0110 0.0012 B 0.003 0.19 1.10 0.110 \ 0.016 0.0014 C 0.086 0.16 0.57 \ \ \ \ D 0.091 0.18 0.56 \ 0.064 \ \ E 0.088 0.17 0.55 0.027 0.070 \ \ seen from Fig.2 that more fine polygonal ferrites, i.e. deformation induced ferrites are formed at lower deformation temperatures.
The role of the first pass rolling at 1000°C is to refine austenite grains by recrystallization considering that fine austenite grains will be beneficial to DIFT.

The in situ observation of the grain trajectories for various values of the temperature gradient demonstrated that gravity and TEM forces were the driving forces which controlled the grain motion.
Depending on the application, one type of grain structure is preferred, e.g. equiaxed grains in car engines and columnar grains in turbine blades.
Absorption was the main source of the image contrast; this depends on the atomic number of the elements and the solute content.
It must be stressed that fragmentation phenomena were very rare in the experiments without any magnetic field, whereas there was a great number of fragments when the magnetic field was applied.
It is worth noticing that the grains continued to grow during their motion.

It is believed that the smaller grain size could improve the mechanical properties.
The process ECAP causes deformation to the separation of grains on heavy dislocation walls [3].
The Grains size significantly decline [4] [5], and dislocation density with ECAP process increased pass number for route Bc [3].
The other effect increase pass number by ECAP toughness improve significantly [9].
The effect of pass number of ECAP process Conclusions In the present work, the commercial aluminum Al-Si-Cu-Mg-Mn alloys were processed by ECAP through route (A and Bc) and the number of passes.

The addition of rare earth Ce can increase the number of hard phase and thus produce more crack initiations, so that the mechanical properties of HMn64-8-5-1.5 brass can be reduced.
Rare earth Ce is a common additive of refining copper alloy grain [7,8].
Fig. 2 Average size of HMn64-8-5-1.5 brass matrix grain with different content of Ce The addition of rare earth Ce into HMn64-8-5-1.5 brass can refine matrix grain, and the effect of refining grain can be more evident with an increase content of Ce.
It contributed to the formation of new grain nucleus, but not to the growth of grain [13,14].
The reasons of refining grain are as above.

The average grain diameter of TiN particles was ~33 nm, while Ni grains measured approximately 53 nm. 1.
When the ultrasonic power was further increased, TiN particles in the composite coating were small in number and exhibited slight aggregation (Fig. 1c).
The reason for this is that nanoparticles that enter and homogeneously disperse in the composite coating lead to an increase in the number of nuclei for nucleation of nickel grains and inhibition of grain growth.
Furthermore, the mechanical force produced by acoustic streams during ultrasonication may break the normal growth of grains and disrupt larger grains to produce smaller nuclei.
Ni grains were also nano-sized, measured as approximately 53 nm.

The plastic flow in fine-grained, polycrystalline Al2O3 takes place mainly by grain boundary sliding or grain boundary diffusion.
The segregated dopant cations change the grain boundary diffusivity and/or the grain boundary sliding itself.
Figure 6 (a) shows a HRTEM image of a grain boundary in Y 3+-doped Al2O3, together with EDS spectra taken from grain interior (b) and the grain boundary (c) using the probe size of 1nm [12].
Moreover, the presence of Y 3+ cation can be detected only from the grain boundary, but not from the grain interior.
These ideas attributed the effects to increment in the number of CSL (Coincidence Site Lattice) boundaries by the dopant [22] and to ionic sizes of the dopants [23].

The grain size of the 1% Mn steel is coarse.
By contrast, the grain size of 2% Mn is quite small.
Also the number of the transformation nuclei is changed.
Rex. 3) Number of transformation nuclei The progress of the transformation is slightly faster with increasing the number, and the transformed grain size decreases (Fig.4(c), Fig.6).
In the experiments, when the transformation initiates at an early stage of the recrystallization, the number of the transformed nuclei increases; this can result in a refined microstructure because the nucleation of the transformation can occur not only at the grain boundaries but also within the deformed grains, which have larger dislocation densities.

There are also a number of other limitations.
It was used to verify the model for static grain growth (GG).
This temperature is close to the solvus temperature of the η-phase [2] that decorates grain boundaries and impedes grain growth.
The average grain size of new RX grains DRX was calculated based on the accumulated plastic work of deformation according to Eq. 5 [[] O.I. 
According to the results of experimental grain size measurement, the initial average grain size of about 10 µm has increased to an average grain size of about 70 µm during the heating operation.

Upon aging, precipitation of σ-phase (~5 mm) and Cr-rich M23C6 (~1 mm) along grain boundary, and nano sized Cu precipitates (~65 nm) in the grain interior were formed.
The size of Cu precipitates was relatively stable, while the fraction and number density increased with the aging temperature/time.
In the aged specimens, one may see that most of the grain boundaries and some of the matrix (grain interior) are precipitated with coarse sized (~1 mm) particles.
It can be seen in from Fig. 4a and b that the particles in size of ~300 nm and ~50 nm are observed at other grain boundaries or grain interior, or along dislocations.
The size of nano sized Cu precipitates was relatively stable, while its fraction (number density) increased with the aging temperature/time.

In the Mg-1Zn-1Nd alloy, grain coarsening is accompanied by a bimodal grain size distribution, whereas in the Mg-4Zn-1Nd alloy, the grain coarsening leads to a uniform grain size distribution.
However, magnesium has limited formability at room temperature due to the insufficient number of slip systems, and thus a strong basal texture after rolling.
The Mg-4Zn-1Nd alloy shows a uniform grain size distribution with an average grain size of ~50 μm, while the Mg-1Zn-1Nd alloy shows a bimodal grain distribution and the average grain size is an order of magnitude smaller, i.e. only ~5 μm.
Precipitates can be found inside the recrystallized grains and also close to the grain boundaries.
It is well-known that solute segregation can decrease the grain boundary mobility and slow down the grain growth rate.