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While the mean grain size reduces to ultrafine-grain regime (257 nm), dislocation motion is still involved to carry the plastic deformation.
Secondly, due to large strain gradients in the inhomogeneous microstructure during tensile deformation, a large number of geometrically necessary dislocation that are forced to be present to accommodate the large strain gradient will induce an additional strain hardening.
In this grain size regime, the NS Ni exhibits narrow grain size distribution (Fig. 2 (e) and (f)) with most of grains locating in "small nano" regime (less than 30 nm) where the normal dislocation activity is already suppressed.
As the mean grain size reduce down into the nano-scale regime, the dislocation accumulation is hard to take place in grain interior.
Dislocations are emitted from GBs and glide through the grain then are absorbed at the opposite side of the grain.

The former has the grain size of 80 mesh, and Table 1 shows its composition; The grain size of the latter one is less than 50 nm,and it is prepared by Hefei Kaier Nano-meter Energy& TechnologyCo.
When the addition of nano TiN is 1%, the nano TiN play a role of nucleating agentto promote formation of large numbers of close grains.
When the addition amount of TiN is 1%, wear weightlessness is 0.1177 mg,reducing by 5.40% than sample of number 0, this is related to that M7C3 separate out as hupereutectic overeutectic carbide precipitation phase.
M7C3 has superior hardness of 672.89 HV and appear in the form of homogeneous grains.
(2)When the addition amount of TiN is 1%, the grain is refined obviously, the wear weightlessness is 0.1177 mg,which means the best wear resistance.

Combining with SEM images (Figs. 1 and 2), it is known that as fZ is below 27%, the ceramics is mainly made up of lath-shaped α-Al2O3 grains and rod-shaped grains.
SEM images show that the crack generally propagates along rod-shaped grains as fZ is below 27% (Fig. 5).
Therefore, as the crack-propagating direction is quite different from both the growth orientation of nano-micron fibers and the axial of the rod-shaped grain, the crack is forced to deflect along the rod-shaped grain due to high elastic modulus of the rod-shaped grain and pinning effect of nano-micron monocrystal fibers around the crack tip, and deflection-induced toughening is properly initiated.
However, the ceramics is comprised of lamina-shaped grains as fZ exceeds 27%, resulting in introducing of a large number of interfaces between the alternating Al2O3/ZrO2 layers into the ceramics, so interface debonding is inclined to take place and deflection-induced toughening is weakened.
As for Al2O3/18%, 21% and 24% ZrO2 composites, the matrix comprised of lath-shaped and rod-shaped α-Al2O3 grains, and within rod-shaped grain the nano-micron fibers are oriented in essentially the same direction.

Similar results concerning Journal Title and Volume Number (to be inserted by the publisher) 3 misorientation inside the {111} <112> and {111} <110> grains, have already been reported from EBSD measurements by Lesne [4] for a 70% cold rolled ultra high purity iron and by Thomas et al
c d b a 9° 3° d c Journal Title and Volume Number (to be inserted by the publisher) 5 Fig. 5 Cell coalescence in a {111}<110> grain after 2 min annealing at 700°C.
(Arrows indicate the bulging in the neighbouring {110}<112> grain; dashed arrows indicate the growth in the "parent" grain).
Generally, the subgrains located inside the grains or at the grain boundary mainly grow inside their "parent" grain.
After cell coalescence or not, subgrains located near grain boundaries grow, either towards the interior of the "parent" grains, or in the neighbouring grain by bulging, even both.

Journal Title and Volume Number (to be inserted by the publisher) 3 Steel C Si Mn P S Cr Al N Nb Ti DIN EN 10084 0,14 - 0,19 ≤ 0,40 1,00 - 1,30 ≤0,035 ≤0,035 0,80 - 1,10 - - - - 16MnCr5+Nb 0,19 0,23 0,74 0,011 0,012 1,19 0,041 0,026 0,045 0,001 Table 1 Chemical composition of the investigated steel, mass content in %.
This gives improved grain size stability at higher temperatures that has been confirmed by grain growth investigations.
The grain size distribution is given by means of the cumulative frequency of grains belonging to different ASTM classes; the approximate average grain size is represented by the 50% cumulative frequency.
Figure 4 Calculated nitride and carbide precipitates. 700 600 500 400 300 200 100 0 700 600 500 400 300 200 100 0 NbC NbN TiN AlN 1000 1200 1100 Temperature, °C Mass fraction of precipitates, ppm Journal Title and Volume Number (to be inserted by the publisher) 5 ening temperature (GCT) is associated to the following limit in this investigation: all grains must be of ASTM size 5 or finer; grains of ASTM size classes 4 and 3 are tolerated up to a total volume fraction of 10%; grains of ASTM size class 2 or coarser are not permissible [6/10].
The grain size stability at elevated temperatures is attributed to a sufficient amount of precipitates which guaranty a grain boundary pinning.

Pearlite nucleates in the austenitic grain boundary, bainite nucleates preferentially in the grain boundary and sometimes in the grain interior and martensite nucleates preferentially in the interface and generally in the grain interior.
Furthermore, the grain boundaries are the favorable channel of the diffusion, so the grain boundaries become the preferential nucleation sites.
It is obvious that the lath martensite can nucleate and grow not only in the crystal grain interiors but also along the crystal grain boundaries and crystal edges.
A large number of observations indicated that martensite can nucleate in the austenite crystal grain boundaries, the austenite crystal grain interiors, the twin crystal interfaces or the phase interfaces.
The experiments show that pearlite nucleates in the austenitic grain boundary, bainite nucleates preferentially in the grain boundary and sometimes in the grain interior, and martensite nucleates preferentially in the interface and generally in the grain interior.

If there are other alloy elements or impurities, it maybe also form a ternary eutectic, its melting point lower than the number of binary eutectic, solidification temperature range should be even greater[10].
Semi-solid material of the microstructure of weld metal From Figure 2 and Figure3 we can see the changing of the aluminum alloy grains through the semi-solid processing and the grains are becoming smaller and more garden the whole grain.
Different grains have different bits to, known as anisotropy.
Thus, in a party up the grain raised on the most vulnerable.
Thus, relatively small grains.

The results show that at 1300℃ a large number of CAS2-Al2O3 caking formed the basic skeleton and some particles were not condensed.
At the same time, little Al2O3 grains are precipitated.
When the holding time extends to 1h, a large number of particles are formed and bonded, the sample porosity reduced and the density increased.
For 4h, the crystal boundaries intersect with each other, the caking body is evener, and a large number of Al2O3 is precipitated.
When the rate reaches 4℃/min, crystal grains are even and clear; grain interaction bond is close, but the blowhole rate increases.

The harmonic structure is composed of coarse grain area (Core) dispersed in an island-like manner and ultra-fine grain area (Shell) that form a surrounding network.
These grains were found adjacent to coarse grains with relatively high dislocation density.
Consequently, preferential recrystallization occurs in the Shell, leading to grain refinement.
It can be interpreted that the refinement of the grain results in grain boundary sliding, particularly in the Shell, as well as Shell/Core unit rotation.
Acknowledgement This work was supported by the Japan Society for The Promotion of Science (JSPS) Grants-in-Aid for Scientific Research (KAKENHI) Grant Number JP18H05256.

It is a material based on a fine-grained cement-based matrix, fiber reinforced, fabric of acrylic-resistant glass, basalt or carbon reinforcement.
The concrete had a fine-grained matrix according to a recipe designed at the Klokner Institute.
The material properties of the matrix and of the glass reinforcements were determined by a number of accompanying tests.
Load displacement diagram: Three thin-walled elements - plates (Tab. 1) made from fine-grained concrete - were subjected to a four-point bending loading test (Fig. 1).
There is also a significant shift of bands around 1000 cm-1 range towards lower wavelength numbers.