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The result is a polycrystalline grain whose crystals have diameters between 0.5 µm and 3 µm with purity of 99.6% [12] providing an abrasive sharp microcrystalline grain.
The microcrystalline grains present grain wear splintering, caused by microcracks resulting from mechanical and thermal tensions.
As the material removal increases, the wear mechanism of flattering grains takes place and, therefore, the grain topography becomes smooth.
Grinding wheels with more microcrystalline grains can maintain the profile edges during the machining process, since the microcrystalline grains are more resistant and can support more process forces than white fused abrasive grains.
Foundry, for the ADI samples supply, and the financial support from CAPES (Process number: 012.043.133).

The size of those equiaxed grains is approximately 100nm.
The laths themselves have a high dislocation density while a numbers of needle-liked precipitations are distributed heterogeneously on the laths.
The equiaxed grains are sub-micrometer with a mean size of 100nm.
The recrystallization nucleus are formed when the sub-grains begin to grow up, which agrees with the sub-grain nucleation mechanism proposed by Cahn [20].
Then the grains together with dislocation cells that have not transformed into sub-grains are retained to form the microstructure as shown in Fig. 6(a).

The atomic compositions of the alloys were Al51Ti40V9, Al47Ti35V18, Al43Ti30V27, Al39Ti25V36, and Al35Ti20V45, the numbers after the elements' names showing their atomic fractions.
The average grain diameter was measured to be about 35µm by the linear intercept method.
Fig.2(e) shows the optical micrograph of the coarse grain beta single phase material 45V whose average grain diameter was more than 500µm.
The 45V alloy containing coarse grained beta phase showed almost negligible deformability at room temperature, but its yield stress was as high as 1000MPa.
The numbers after the element symbols shows the atomic % of the element

Figure in the left below shows the geometry and number of counted pores to the total open porosity of the material.
First reason is weak adhesion of binder to the grain of aggregate and roughness its surface.
The second type of pores appears in the structure of sand grain, because material is not solid.
NSC includes both the type of pores: few of large (manufacturing origin) and a lot of tiny pores (weak adhesion of binder to the grain of aggregate and roughness its surface).
Acknowledgement The research was supported by Grant Agency of the Czech Republic under the number GACR 15-10591S.

For example, the fine-cell grains are usually considered to be “normal” grains belonging to the particular section of the billet where they are found.
This fact is confirmed by measurements of composition of fine-cell grains [12].
On the other hand, the amount of floating, coarse-cell grains sharply increases in grain refined billet, coarse-cell structure becoming dominant.
Grain refining facilitates thermal expansion.
A number of theories and hypothesis has been suggested over the years for the mechanisms nucleation and propagation of hot cracks.

Both grain and bonding wear occurs.
There are no damages at the grain and following favourable for the cutting process
The grain retaining forces of the bond are not sufficient due to a too soft bonding system.
In combination with the grit size parameter, the concentration is a measure for the number of active points in the cutting process.
To characterise the cutting bead the concentration of the tool is corresponding with the basis number C100 which means 4.4 carats/cm³.

Concurrently we measured the sizes of corresponding grains.
Along with microhardness measurement we measured the sizes of corresponding grains.
The average number of roughness coefficient Ra is 100 nm for AN-35, and 121nm for PG-19N-01 (Fig.1).
Space group number.
We explained the dependence of microhardness on the linear sizes of grains by the Hall-Petch equation (1) (1) where Н is microhardness, actually the strength property; k is the constant, connected with the transfer of deformation through grain boundary; Н0 is the strain connected with energy dissipation in motion dislocation in infinitely great grain; d is the size of a grain.

Low weld heat input can increase the volume of acicular ferrite in the welding joints, and increase the numbers of the dislocations correspondingly.
By increasing the weld heat input 15 kJ/cm, it would promote the growth of the ratio of granular bainite as well as the decrease of the volume of acicular ferrite, resulted in the decrease of the numbers of the grain boundaries in the deposited metals.
When the carbon rich film diffuse along the grain boundaries, where the stress appeared for its volume difference with the acicular ferrite, in addition that the grain boundaries are exactly high energy regions, this process of the carbon film diffusion would significantly increase the potential energy of the grain boundaries.
Besides, the area of the acicular ferrite grain boundaries would increase the corrosive activity of the deposited metals [11].
(3) There are abundant fine acicular ferrite and high density dislocations in the deposited metals welded at 10 kJ/cm weld heat input, and the larger grain boundary areas and higher grain boundary energy exist in the deposited metals welded at 20 kJ/cm weld heat input, as may be the main reason why the deposited metals has poor anti-corrosive properties at lower or higher weld heat input.

Results and discussion TEM examinations and microprobe analysis TEM examinations reveal a very fine and uniform microstructure with elongated grains in the extrusion direction and equiaxed grains with a size up to a few hundreds of nanometers in the transverse direction (Fig. 1a,b).
This might be due to an abnormal grain growth which leads to a bimodal grain size distribution as observed in the MA957 ODS steel in [1] (the misoriented grains grow first in fine grained matrix because their boundaries move easily).
After a heat treatment of 1 hour at 1450°C, the material is completely recrystallized and the grain boundaries are impinged by particles (figures 4b).
During this primary recrystallisation, it is possible that the grain size was only slightly modified at a sub-optic scale.
Indeed, as the initial grain size is very fine (around a few hundred of nanometers according to fig. 1), the sub-grains which are formed after elimination and/or rearrangement of dislocations can not move over a long distance due to the large number of original grain boundaries.

It is also known that microstructure refinement to the nanometer scale enhances strength [7] and reduces radiation embrittlement due to an increased number of defect recombination sites [8].
Generally, nDiamond particles are present at the grain boundary of copper grains, although in some instances they appear inside copper grains (see arrows).
The arrows point to nDiamond particles inside copper grains.
Size distribution of copper grains.
The grain size distribution of both phases was determined.