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Fig. 4 Grain size distribution curves for subgrade and sediment with upper and lower subbase layer Class B limits.
Grain size distribution.
Fig. 7 Grain size distribution curves for subgrade and sediment with upper and lower limits of base layer Class B.
Fig. 8 Grain size distribution curves for subgrade and sediment with upper and lower limits of base layer Class C.
Also, it is noticed that the optimum number of blows for both materials is 30 blows to find the optimum of CBR.

The PEFCs have a low operating temperature, 80 °C, which implies a number of advantages, as well as some limitations compared to other FCs.
From a technological perspective, there are a number of limitations for practical applications of PEFCs.
In this case, SDC grains were dispersed in a YSZ matrix, so the electrons caused by SDC can be effectively blocked by the YSZ matrix.
The Ni/Al metal (oxide) particles distributed in the GDC framework/grains are somehow connected with each other, at least in a localised region.
In the CMCs, the metal can also promote this situation through directly bring semiconducting sites in the composite material grains and interfaces.

A large number of different CFC armoured mock-ups with different armour materials, different joining techniques, and different geometries has been included in the test matrix so far.
Fig. 5 illustrated this effect for an isotropic fine grain graphite: the left column represents digital images taken during 5 ms electron beam pulses applied in the HHF test facility JUDITH.
The current plots (current absorbed by the test samples vs. time) show a clear current decrease and a number of spikes which are presumably associated with the emission of dust particles.
The size of the dust particles which has been analyzed by SEM and optical microscopy was found to cover the full range from nanometre scale to approx 100 µm (clusters of grains in or fibres) [8].
Conclusions Carbon based materials are characterized by a number of favourable properties such as a low atomic number Z, the non-existence of a liquid phase and a low activation by neutrons; in addition, special multi-directional carbon fibre composites have been developed with an excellent thermal conductivity and an suitable mechanical strength.

According to the authors of works [4, 11 - 15] in the case of alloys with higher Mg and Si content, a high number of clusters with high Si content are formed during the natural aging of alloys.
Equiaxed grains of solid solution having an average size of about 22 μm and dispersed particles of AlxFeySiz phase were observed in alloy microstructure.
The dispersive particles, probably of AlxFeySiz phase were found in the solid solution grains and on their boundaries.
Extremely fine and dense particles, probably of the β″- phase, were observed inside the grains of solid solution with low dislocation density.
In the substructure of analyzed EN AW 6063 alloy states, that were maximally hardened during artificial aging after quenching and natural aging for 100 and 10000 hours, the very fine particles with high number density were observed in the interior of alloy solution grains with equiaxed morphology.

Though the improvement has been demonstrated, its mechanism remains in controversy between implication of quench-induced dislocations [2] and grain-boundary structure evolution [3,4,5].
Grain Boundary structure Precipitate-Free Zones are clearly recognizable along the grain boundaries in all the 4 samples examined here.
Furthermore, in the same sub-GB, they are oriented all in the same direction, depending probably on certain crystallographic orientations of adjacent sub-grains.
This is due presumably to an increase in number density of the precipitates promoted by an increased super-saturation of solute atoms due to lowering the ageing temperature after coldwater quench.
The grain boundary structure is not significantly different between (c) and (d), as can be seen on Table 2.

A number of different approaches, based on the sintering models focused on a specific idealized geometry represented by only one of the three stages in the sintering process, have been taken in attempts to elucidate this densification behaviour [2-4].
The combined-stage sintering model relates the linear shrinkage rate of a compact at any given instant to the grain boundary and volume diffusion coefficients, the surface tension and certain aspects of the instantaneous microstructure of the compact.
In this model, the instantaneous linear shrinkage rate is given as [7]:             ⋅⋅Γ +      ⋅Γ ⋅      ⋅Ω⋅ =⋅− 4 3 G D GD Tk dT L dL b b VV δ γ , (1) where (dL/L) dt is the normalized instantaneous linear shrinkage rate, γ the surface energy, Ω the atomic volume, k the Boltzmann constant, T the absolute temperature, G the mean grain diameter, Dv and Db the coefficients of volume and grain boundary diffusion respectively, δ the width of the grain boundary, Γv and Γb are of microstructure scaling parameters for volume and grain boundary diffusion, respectively.
Commonly, grain growth is independent of densification, but during constant heating rate experiments below theoretical density it can be assumed [5] that the grain growth depends on density only.
While the dominant sintering densification mechanism is volume or grain boundary diffusion, most of the materials densify through a mixture of densification mechanisms.

We have recently derived a new equation that links the martensitic transformation temperature not only to the carbon content of the austenite grains but also to the grain size [5].
Austenite and martensite appear in white, while bainite and ferrite grains are shown in brown.
Moreover, a fraction of the initial metastable austenite grains still remain untransformed at the lowest temperature of 100 K in all samples.
These remaining austenite grains are too stable due to a high carbon content and a small grain size that gives a very low value for their martensite transformation temperature. 4.
Acknowledgement This research was carried out under the project number M41.5.08313 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl).

The markedly improved contribution of effective stress in the new N+C austenitic manganese steel was attributed to the enhanced short-range order caused by N+C alloying, whereas the decreased effective stress with the number of cycles was due to the broken short-range interaction.
The fatigue failure was judged as the cycle number when the tensile peak stress decreased to a value approximately 25% below the plateau stress.
Fig. 3 Tensile peak stress vs. the number of cycles, N (a) and strain amplitudes vs. number of reversals to failure, 2Nf (b).
Note: the white arrow represents the crack along the slip bands while the red arrow represents the crack along the grain boundary.
The slip bands and grain boundary were the preferred places where short crack inititiated and propagated due to the plastic strain localization.

Moreover, functional properties strongly dependent on the microstructure, i.e. grain size and texture [21, 23, 24].
A number of weld beads were deposited adjacent to each other in a defined scanning direction, creating a single layer adherent to the substrate material.
In addition, the grains are elongated in build direction, which can be attributed to epitaxial grain growth during build-up.
The optical micrograph reveals relatively fine columnar grains being slightly inclined towards build direction.
Furthermore, superimposed patterns are seen and the grains are much smaller than in CoNiGa.

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