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Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman.
A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain.
The characteristic length is inversely proportional to a so called brittleness number B [3]: . (5) In Eq. 5 L is a significant specimen dimension.
Fig. 1: Schematic drawing of wedge splitting test according to Tschegg [4,5]; numbers and symbols are explained in text.
The Matrix contains the majority of the porosity, strength of the matrix and especially the grain/matrix interface is expected to be considerably lower than that of the grain.

A large number of pores, high water consumption, and weak supersaturation of the solution characterize the concrete made of such cement and lead to decrease in the strength.
The sand fineness modulus Mfn = 1.29: no grains larger than 5 mm; the share of grains with a diameter of less than 0.16 mm is 8.7%; the content of pulverized and clay particles is 0.84% [7].
Research Results The cement grains have sizes from 1 to 100 μm [8, 9].
Ivanov-Gorodov believes [10] that uniform and rapid hardening of cement is achieved with the following grain compositions: grains smaller than 5 μm compound no more than 20%, grains of 5-20 μm in size are about 40-45%, grains 20-40 microns in size - 20-25%, and grains larger than 40 microns - 15-20%.
Concrete obtained using cement mechanically activated in the activator Pulverizette-6, has a more loose structure with a large number of different forming elements.

Both coarse and fine grained CM247LC showed similar cyclic stress response, however, the fine grained CM247LC specimen exhibited relatively uniform and superior fatigue properties to the coarse grained one.
Experimental procedure Coarse grained (CG) and fine grained (FG) bars were prepared by vacuum investment casting of CM247LC.
Number of cycles corresponds to 80% drop in maximum tensile stress of the alloy was defined as fatigue life.
Relatively large amount of microporosity in FG was attributed to restriction of capillary feeding in mushy zone due to increased amount of grain boundary area and number of grains.
Number of cycles to failure as a function of total strain range.

Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities.
Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities.
The volume fraction is 0.0026% and the number density is 0.0463 mm-3.
S9 (a) Band contrast (BC), (b) inverse pole figure taken from only the secondary α-Al grains, and (c) the number fraction of the secondary α-Al grains in the long thin samples with a relatively higher cooling rate produced by Al-7Si-0.3Mg based alloy with the recycled secondary materials of 20 % (F).
S11 Band contrast (BC), (b) inverse pole figure taken from only the secondary α-Al grains, and (c) the number fraction of the secondary α-Al grains in the large thick samples with a relatively lower cooling rate produced by Al-7Si-0.3Mg based alloy with the addition of recycled secondary materials of 30 % (H).

At 20 % deformation a relatively large number of voids can be observed.
At 70 % cold work the number of voids is smaller than at 20 %, but their shape is again almost spherical.
They number is not different from that recorded at 70 % cold work.
Continuous deformation leads to new grain formation, and the number of the grains increases as the forming degree increases.
From figure 3, it is also observable that the number of the grains is not changing appreciably, only the shape of the grain become more elongated.

The rotating bending processes carried out with various conditions show that the grains in cross-section and longitudinal section of magnesium alloy tube were refined for all samples by the rotating bending process with rotation speed of 20r/min for different rotation numbers and temperatures.
It can be seen that the grain number increased significantly in the relative area after rotating bending process.
After plastic deformation at low temperature region (150 and 200°C), the dense dislocation piled up in the interior of grains accompanied by the forming of a large number of twins.
The average grain size was reduced due to the newly formed fine grains.
As the grain size is small, the strong deformation had little effect of on the grain shape as well as grain boundaries.

Such nanocrystalline electrodeposits are in thermodynamically non-equilibrium (metastable) states, i.e. high energy states due to a large number of interfaces [8-10].
Since nanocrystalline materials are in high energy states due to a large volume fraction of the interfacial components such as grain boundaries and triple junctions, the driving force for grain growth is so large that the grain boundaries can move far below temperatures at which grain growth is expected to occur in coarse-grained materials.
Gray-colored grains indicate the <100>//ND grains.
The activation of grain growth may depend on the crystallographic orientation of each grain as-deposited, and it is obvious that the growth rate of the <111>//ND grains is highest.
Thus, what should be explained is why the abnormal grain growth occurs selectively for the <111>//ND grains.

Phase material microstructure and grain area ratio directly affects the material uniformity, uniformity of material differences caused by different grain characteristics which ultrasound parameters.
Thus, studying further on the changing relationship between velocity and grain size is also necessary.
Figure 5-1 Proportion of the α phase of the sample grain and trend of the ultrasonic velocity The relationship between the area ratio of α phase of sample and acoustic attenuation coefficient When the acoustic wave spreads in the medium of uniform grain material, the scattering due to the grain boundaries will cause the attenuation of sound waves.
In the heat treatment process, with the α-phase single area ratio and the ratio of the number increases, the scattering when sound wave spreads in media aggravates, resulting in the increase acoustic attenuation coefficient.
With the increase of the ratio of α phase of the grain, it will lead to the variation in elastic modulus and density.

The alloy shows typical equiaxed b grains with second phase precipitation and twin formation inside the b grains in the as-rolled condition.
Solution treatment at lower temperature led to a smaller b grain size while higher temperature solution treatment produced coarse grains with increasing precipitated phases inside the β grains.
After double solution treatment and ageing, the alloy has an increasing number of α phase particles at the grain boundaries, locally connected like a pearl necklace and a further coarsened β phase structure as shown in Fig. 1d.
For the solution treated and aged sample, thermal exposure increased the β grain size and the number of precipitates appearing within the grains.
Funkhouser, Coating for prevention of titanium combustion, NASA report number CR-165360, 1980

The solution with the greatest number of votes is deemed the most likely.
Comparisons are then made of the number of observed spots in the RDP with those predicted in a simulation of the pattern using the mean orientation.
Numerous studies have been made using the DFC procedure to form OIM images on a large number of materials most of which were single-phase materials.
The number of spots observed was also less than what was seen in a selected are diffraction pattern recorded from the same area.
Hence grain map 6b is a better representation of the grain contiguity than that shown in figure 6a.