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As reported earlier [7], the 2195-T8 base alloy consisted of pancake-shaped grains with a thickness of ~10 μm and a diameter of ~100 μm, as shown in Fig.1(a).
TEM observations and X-ray diffraction revealed that the HAZ simulation removed the T1 phase, and was replaced by TB (Al7Cu4Li) phase mainly along the grain boundaries (GBs).
da/dN, m/cycle ΔK, MPam1/2 2195-T8 RT, 50 Hz R=0.25 0 50 100 150 200 250 300 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08 Number of cycles to failure, Nf W, R=0.05 PWHT, R=0.05 Stress amplitude, MPa 600o C, R=0.05 T8, R=0.05 T8, R=-1 Fig.3 Microhardness as a function of the HAZ simulation temperature.
Fractographic examinations indicated that the tensile fracture of the base alloy exhibited shear steps, with the step height almost equal to the thickness of the pancake shaped grain structures.
Heat-affected zone (HAZ) simulation resulted in the dissolution of T1 phase and the formation of TB (Al7Cu4Li) phase and voids/microcracks along the grain boundaries (GBs). 3.

We adopted a commercial phenolic resin "novolak" FB 8230 produced by FERS-RESIN SA (Spain), graphite powder with fine grain by ASBURY (USA) and with coarse grain by TIMCAL (Canada).
At first a low amount of resin (5 wt%) was used to keep low the number of cracks and defects related to the reduction of gas emission during pyrolysis, but on the other side, a lower sample compaction after cold compression was observed.
In Fig.3 the sample before thermal curing step is shown: the various precursors and grain size can be easily recognized.
In the reaction bonding cure at 1500°C, the formation of hexagonal grains, typical of hexagonal SiC formation, is evident (Fig.4).
Figure 3: SEM images of the green sample (MIX.1) before the two heating steps Figure 4: Sample (SiC40) evidence of hexagonal SiC grain growth after reaction bonding Figure 5: Sample (SiC45) after reaction at 1500°C; carbon fibres are distinguishable Tribological properties have been studied with dynamometer machine.

Adsorption techniques enable measurement of the specific surface area and then, assuming the shape of the grains, their mean size.
The grains between 1.2 and 1.5 mm were separated for further experiments.
The grains were reduced with a nitrogen-hydrogen (1:3) mixture, under atmospheric pressure, at a slowly-rising temperature from 200 to 500 O C for a the total reduction time of 72 hours, with flow of 25000 h-1.
The grains of the materials have to be homogeneous regarding the size distribution of the nanocrystallites.
For coarse grain materials the nucleation models are known, in which diffusion processes play the most important role.

Therefore, a number of studies have been carried out to improve electrical properties of BNT by the formation of solid solutions with other ABO3 perovskites [4-5].
The FE-SEM micrographs show the typical BNKT morphology consisting of very small faceted grains.
Furthermore, it was determined that sintering temperature affects the grain size and the amount of the secondary phase.
All systems show small grains (≤ 1 μm) that become finer at low sintering temperatures.
In these samples, the improvement in the real permittivity value with the sintering temperature could be related to the secondary phase formation, the grain size increase and the densification degree.

Introduction Bismuth layer-structure ferroelectric ceramics (BLSFs) have a general chemical formula (Bi2O2)2+(Am-1BmO3m+1)2-, where A is mono-, di-, or trivalent cations, B is tetra-, penta-, or hexavalent cations of a transition metal, and m is the number of perovskite-like layers.
No second phases are detected at grain boundaries, which is consistent with the results of XRD.
In addition, grain micrographs of all the specimens are ruptured.
Average grain size of the SLBNO ceramics decreases significantly due to the introduction of the lanthanum ions, which indicates that the grain growth of the SLBNO ceramics is suppressed.
Sakata, Grain orientation effects on electrical properties of bismuth layer-structured ferroelectric Pb(1-x)(NaCe)x/2Bi4Ti4O15 solid solution, J.

As a result, cracks are likely to be happened along the grain boundaries or tabular Mg2Si itself and therefore formed crack source.
Moreover, the cross shaped primary Mg2Si appears and the thread-like eutectic Mg2Si continuously assembled and formed Chinese script microstructure whose average size increases; as shown in Fig.2 (d) and Fig.2 (e), when 1% of rare earth Ho is added, a large number of cross shaped primary Mg2Si microstructures cover the matrix, the morphology of eutectic Mg2Si is characterized by Chinese script, fishbone-like or dendritic, and the microstructure size is enlarged.
Fig.3 Average sizes of primary Mg2Si crystalline grains after modification using rare earth Ho with different contents. 2.3 Mechanical properties Fig.4 is a comparison diagram of the mechanical properties of the alloy modified using rare earth Ho with different contents.
This is probably caused by over-modified phenomenon, which results in the enlargement of grain size in the alloy and the decrease of mechanical properties.
Regarding in-situ 20%Mg2Si/Al composites, the modification effect is optimal when the Ho content is 0.4%: the average grain size decreased from 74 μm before modification to 16 μm; meanwhile, the tensile strength of the material can reach 174.6 MPa and the brinell hardness is up to 90 HB.

Underwater distributary channel is the land branch channel underwater extension,due to the lake in the extension process,the river widens, slow flow velocity, sediment accumulation rate increases and the formation of.Sediment grain size is relatively coarse, thick layer of gravel sandstone and fine sandstone (Table 1),separation of grinding medium.The bottom visible erosion filling structure (Figure 4-A), mud gravel layer (Fig. 4-b, 4-C) and mudstone rip up clasts (Figure 4-D),development of trough cross bedding, wedge shaped cross bedding and parallel bedding bedding types.
Table 1 Sandstone grain size characteristics of Qingshui River group in the Zhunzhong area well number Depth m Sorting coefficient Average particle sizemm Lithology Quasi sand6 3259.1 1.79 0.28 Inequigranular sandstone Yong 1 5828.0 2.32 0.12 Silty fine sand Yong 6 5969.9 2.25 0.17 Silty fine sand Yong 9 5867.9 1.92 0.22 Silty fine sand Front sheet sand, is a product of the underwater distributary channel sand, mouth bar sand lake waves and longshore currents transformation.The thickness of single layer thin sand body,the average thickness of 2-3 meters,the powder sandstone and argillaceous siltstone, mudstone is the main features of the lithologic association,sorting, round in shape.Common wavy composite bedding sandstone (Figure 4-e), the wave into the sand bedding (Figure 4-f) sedimentary structures.Well logging curve showed knife, finger like features.The
probability curves of grain size due to lack of rolling components,in two hop a suspension type mostly, reflects the interaction of river and lake waves
(2)Beach bar facies Developed in the shallow part of beach bar,the main subject of wave and lake current and transportation and redeposition formed.Since the sand body after handling and screening of long distance,the grain size is fine, lithology is mainly composed of silty mudstone and siltstone, sorting and roundness.By the modification effect of wave strong,common washing bedding (Figure 4-g),the plane peel lineation structure development,also visible more bioturbation structures (Fig. 4-h).Well logging curve in reverse order characteristics,the probability curves of grain size as jump a suspended two segment for the

The number of graphene layers is not uniform on the Ni surface.
The film is composed by ~20–30 nm crytalline grains.
According to X-ray diffraction analyses (see Fig.4), most of these grains are (111) oriented.
Ni grains size further increased (up to ~0.5 mm).
Furthermore, superimposed to the Ni grains is evident a network of wrinkles.

A number of the liquidus projections obtained either experimentally or thermodynamically calculated have been reported for the Mo-Si-B system.
Alloy 1 had a homogeneous microstructure consisting of Moss, T2 networks and a small amount of Mo3Si grains, which corresponds well to the ternary phase diagram.
Some primary Moss areas are assumed to have merged together and small Moss grains distributed homogeneously between primary Moss areas.
Alloy 4 had a simple microstructure, that is, small Moss grains were distributed homogeneously in the matrix of T2.
In Alloy 3, primary angular T2 areas remained after heat treatment, with a homogeneous microstructure consisting of Moss, T2 and Mo3Si grains developed between the T2 areas.

The secondary phases mainly locate at the grain boundaries.
It is indicated that this phase located at grain boundary is the W-phase with face-centered cubic structure [11].
In addition, the long strip quasicrystalline I-phase distributed in the grain boundaries were observed by TEM observation, which was not shown in this paper.
Additionally, both the I-phase in spherical morphology and the Mg4Zn7 phase have been found in grains of this alloy.
According to the Hall-Petch relationship, the refinement of the grains contributes to improvement of the YTS effectively.