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The major reason for the benefits mentioned above is a shift in the wear behavior of the active grains away from the flattening and blunting of the grain tips toward an increased micro-splintering.
The increased grain related normal forces and the highly dynamic force action promote a self-sharpening of the active grain providing a permanent supply of sharp cutting edges.
Due to the statistical nature of the size and shape of the abrasive grains a large number of actual grains was analyzed using SEM-pictures from different view angles.
Easily to detect are the scratches left by the penetrating grain.
Subsequently a number of different simulations have been carried out applying the CFD-software FLUENT of Fluent Inc.

There is not enough time for the dendritic crystal to change into the grain with particle-like morphology, so that the dendritic crystal is reserved at the form of rosette-like grain.
The results show that the nucleation sites for primary α-Al quickly spread throughout the whole melt region and the number of nuclei can be increased at the same time.
So the grain density is high enough in the early stage of solidification and the spherical primary α-Al grains are formed in the end.
The grains become fining and their distribution is more uniform.
In the range of researched temperature, the shape of primary α-Al experiences a transition from rosette-like grains to spherical grains with the pouring temperature lowing gradually, and the smaller grains with a spherical appearance distribute in the microstructure homogeneously

Large number of welded elements operate under fatigue load conditions.
The measurements were performed with an accuracy up to 0.01 mm with numbers of loading cycles N recorded.
This material has fine-grained ferritic-pearlitic structure with fine equiaxial ferrite grains and very fine pearlite grains of strip pattern.
The HAZ shows coarse acicular structure of martensite and upper bainite of Widmanstatten pattern, lower bainite structure, fine-grained normalised zone (formed at heating of native material above A3), partially re-crystallized zone of non-uniform grain size with relatively large ferrite grains and very fine pearlite grains (Fig. 4b-4e).
Figure 7 presents examples of curves of fatigue crack lengths as a function of number of cycles for obtained experimental results.

Introduction Up to now, many different severe plastic deformation (SPD) processing techniques have been proposed and developed in order to produce ultra-fine grained (UFG) or nano-grained materials.
Based on the conventional equal channel angular pressing technique, a modification has been proposed recently aiming to reduce the number of process passes for the same degree of grain refinement, in which the widths of two die channels were considered to be different and the process was called Non-equal channel angular pressing [8-10].
According to the experimental study of AA2124 aluminum alloy [9], much finer microstructure was obtained and more elongation in the grain shape has been observed, which helps grain subdivision during deformation.
Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog.
Sun, Ultrafine grained AA1050/AA6061 composite produced by accumulative roll bonding, Mater.

It was found that the solution treated alloy at 950 ºC produced small grain size and alloy treated at 1100 ºC produced large grain size.
This is due to the accessibility of high ion diffusion route through the grain boundaries of small grained alloy and thus permit the speedy establishment of the initial oxide layer.
SG sample has a grain size of 54 μm and LG sample has a grain size of 65 μm.
This phenomenon was due to the higher ion diffusion on small grain sample at relatively high grain boundary area that produce rapid initial oxide layer.
Acknowledgement The authors would like to acknowledge the support from the Ministry of Higher Education Malaysia from the Fundamental Research Grant Scheme (FRGS) under a grant number of FRGS/1/2020/TK0/UNIMAP/02/43.

LiTaO3 grains were nearly worm.
It can be seen that Li2CO3 grains are like columns and Ta2O5 grains are polygonal.
The grain sizes of both Li2CO3 and Ta2O5 are not uniform and are averaged at about 5um.
LiTaO3 grains were almost like worm.
Acknowledgments This work was financially supported by National Nature Science Foundation of the People's Republic of China under grant number 50572098 and Foundation of China University of Geosciences, Beijing, under grant number 200403.

In 2008, the number of EBSD investigations concerning hexagonal metals has increased twice in comparison to 2003 [1].
However, some of the grains resist to this behavior.
The size of recrystallized grains clearly depends on the prior rolling reduction degree, which means that a higher deformation produces a higher number of nuclei.
Authors gratefully acknowledge NCN for the grant number 2011/01/D/ST8/07399.
Sandim, Annealing behavior of coarse-grained titanium deformed by cold rolling, Mater.

The actual austenite grain size tests were carried out by oxidation method [12], and the actual austenite grain appearance is shown in Figure.2.
Using the comparative method [12], the average actual austenite grain-size number of original state was evaluated for 8.5.
The above data show that the grain grows up gradually and the actual austenite grain size number becomes smaller and smaller with elevated temperature.
The transformation process is governed by nucleation and growth, hence any single grain or colony will give rise to more than one new grain because there are several grain boundaries and several nucleation site in each grain.
When the temperature is heated to 1100℃, the actual austenite grain size number of samples is the same as original one, and the trend of grain growth is not obvious.

In the HAZ were recognized three different sub-zones namely coarse-grained, grain refined and intercritical zone (Fig. 3) [5].
EBSD analyses showed that cavities are formed in the fine-grained structure containing high number of HAGBs with random misorientation (Fig. 4b).
From this reason these grains are so fine that strain-induced subgrains are not formed in their interior but dislocations are stored by their enhanced recovery at grain boundaries [9,10].
The results demonstrate that area of coarse grains contains parallel boundaries.
Wang, Deformation resistance in the transition from coarse-grained to ultrafine-grained Cu by severe plastic deformation up to 24 passes of ECAP, Mater.

The evolution of the grain boundary and the grain size were investigated, from the as-cast to the recrystallized state.
Results show that the recrystallized single phase FCC structures exhibits different twin grains density, grain size and recrystallization temperatures as a function of the at.% of modifier alloying elements added.
The promotion of grain boundary migration and the twinned microstructure, characterized by different grain size lead to a FCC structure (Fig. 3) as confirmed by XRD diffraction pattern (Fig. 2).
A high temperature for recrystallization is essential for the Cu-HEA, but renders the microstructure instable as the smaller recrystallized grains are consumed by excessive growing of a few grains, i.e. secondary recrystallization [18].
As already known, the addition of Zr in equiatomic HEAs promotes recrystallization following cold deformation and gives a microstructure composed of a large number of fine grains which increases the strength of the alloy [24].