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Investigations by means of confocal laser scanning microscopy (CLSM) revealed that the slip band density in these grains increases with the number of loading cycles and remains constant in the very high cycle fatigue (VHCF) regime.
In contrast to electrolytically polished samples, mechanically polished samples showed a fatigue limit at a load amplitude of about 370 MPa and at higher amplitudes an about four times higher number of load cycles to failure.
The length of the left and right branch of the fatigue crack as a function of the number of load cycles is presented in figure 5b.
A trans- and an intergranular fatigue crack initiated towards the ferrite grain α2 at phase boundaries.
The height of extrusions and depth of intrusions in austenite grains increase within relatively low numbers of load cycles and subsequently saturate indicating a strong cyclic hardening within the austenite slip bands.

The microstructure was effectively refined and the mean grain size was decreased from 800 μm to 3–15 μm.
The number of extrusion passes was defined as the number of the specimen passed through the die.
Results and Discussion The mean grain size of the as-received Mg-3Y alloy was estimated to be around 800 μm.
New recrystallized fine grains with new misorientations could easily form at prior grain boundaries during CEC.
Compared with the conventional extrusion, the maximum texture intensity Mg alloys diclined with the increasing number of passes [6,8].

The grain orientation is randomly assigned to grains, and zero-thickness cohesive elements are embedded on grain boundaries and inside grains.
The total mesh number is 9383.
Picking three numbers n1, n2, n3 randomly between 0 and 1, and then computing the three Euler angles ( in degrees) as: (2) The code can accomplish the orientation assignment to each grain quickly.
The number of grains in each microstructure is 50, 100, 150 and 200, respectively, and the corresponding average diameter d is 0.2 μm, 0.1 μm, 0.067 μm and 0.05 μm, respectively.
Zero-thickness cohesive elements are embedded inside grains and on grain boundaries, and the grain orientation are randomly produced and specified to every grain.

The corrosion tests results indicate that there is a potential difference between grains and grain boundaries due to the precipitation of chrome carbide at grain boundaries, resulting in pitting corrosion occurred preferentially at grain boundaries, consequently, the corrosion resistance of Ni-based alloys is reduced.
Data showed that [10] when more higher solution heat treatment temperature, the grain boundries lost the pinning effect of original precipitated phase and the grain size growing up quickly.
There exist a mass of long strips or flake precipitated phase in intragranular as shown in Figure 5a, the number increase relatively with temperature increasing[11].
The TEM observed that the flake phase at grain interior was M6C, and the continuous-chain phase at grain boundary was M23C6 (Figure 6).
It can been seen from TEM that new carbide phase M6C was observed, and the number of M6C phase increased obviously and formed easily at high temperature.

Because the number of strengthening phase particle Al3Zr increases greatly near fusion line after PWHT, the ratio of heterogeneous nucleation further increases, consequently, it promotes the formation of fine equiaxed grain.
The microstructure of weld metal has been changed from equiaxed dendrites to equiaxed grains after PWHT, the number of eutectic structure greatly decreases.
Because the weldment consists mainly of eutectic structure in AW condition, and the number of strengthening phase precipitating within grain is small, moreover, the precipitate free zone (PFZ) with relatively low strength does not generate at grain boundary, consequently, under the action of tensile stress, plastic deformation proceeds dominantly within grain.
It proves that the weldment mainly consists of equilibrium phase δ in AW condition, and the number of strengthening phase is lower.
Through analysis, the rod-like phase should be T(Al2MgLi) phase, and the number of δ′ phase is very small around the T phase.

Thus, the most two important parameters in the HPT process are the number of revolutions, and the imposed pressure.
Increasing the number of revolutions up to 4-revolutions revealed further refinement of the grains, subgrains, and substructure sizes to 30, 1.9 µm, and 250 nm (in Fig. 1b).
Due to the SPD induced with increasing number of revolutions up to 4 revolutions under a pressure of 3 GPa, the consolidated equiaxed powders subgrains were elongated but rather in different directions following the orientation of slip planes for the non-directional grains.
Because of the intense deformation per revolution, it was suggested that enormous numbers of dislocations were generated so that the subgrain boundaries further evolve into grain boundaries with large angles of misorientation which is usually assisted with dynamic recovery [13].
HPT processing was conducted under different conditions of pressures and numbers of revolutions.

�Grain boundary carbides-related parameters, such as number or area fraction, were sometimes reported to have favorable correlations with thermal degradation [5].
In this work, AGBC was defined as the total area of grain boundary carbides divided by grain boundary length examined.
FGBM6C was defined as the number of grain boundary M6C carbide (i.e., Fe>Mo>Cr) divided by number of total grain boundary carbides analyzed.
The different characteristic of grain boundary carbides with those of carbides inside grains needs to be independently monitored for assessment of thermal degradation.
� ������� � 0 10 20 30 40 50 60 0.08 0.10 0.12 0.14 0.16 0.18 480 500 520 540 560 580 600 620 640 660 Fraction of GB M6C Carbide (R=0.89) Fraction of GB M6C Carbides [%] UTS [MPa] Total Area of GB Carbides (R=0.74) Total Area of GB Carbides/GB Length [µµµµm] 0.08 0.10 0.12 0.14 0.16 0.18 80 84 88 92 96 100 Rockwell Hardness [HRB] Mean Size of Carbides [µµµµm] Globular (M6C) Carbides (R=0.95) All Carbides (R=0.83) 0 1000 2000 3000 4000 5000 0 10 20 30 40 50 60 Theraml Degradation Time [hour] Number of M6C carbides x100 Number of grain boundary carbides analyzed Fraction of M6C Carbides at Grain Boundary [%] Kinetic Energy [eV] Intensity [arbitrary] (a) (b) Fe Fe C Cr Mo C Mo Kinetic Energy [eV] Intensity [arbitrary] (a) (b) Fe Fe C Cr Mo C Mo Fig. 8 Correlation of total area of grain boundary carbides and fraction of grain boundary M6C carbides with tensile strength.� Fig. 5 Typical

Because of the high vibration frequency of the system, the sample surface was peened repetitively by a large number of balls within a short period of time.
With successive grain subdivision, the grain refinement continues and hence, the ultrafine and nc grains are formed, as shown in Fig. 3(a) and (b) at ~ 70 and 25 µm deep, respectively.
Fig. 5(a) shows a grain of ~ 80 nm in size.
The grain refinement stems from grain subdivision due to {1010 }〈1120 〉 prism and {0001}〈1120 〉 basal slip.
The grain refinement of ε-cobalt is realized through grain subdivision by the {1010 }〈1120 〉 prism and {0001}〈1120 〉 basal slip.

Segregation of calcium to magnesium oxide grain boundaries F.
In the case of grain boundary 3, it is nearly 40%.
We assume that this is because the grain surfaces are not strictly planar.
Fig. 3 shows two sides of a fracture surface, with a certain number of GB facets identified on the "left" and "right" sides.
Acknowledgment The authors wish to acknowledge with thanks support of this research by the MRSEC Program of the National Science Foundation under award number DMR-0079996.

It was found that if the volume and property of the paste that remains after filling the space in between the aggregates in compacted state is kept constant, the consistency of a mixture can be characterized by the number of aggregates corresponding to each grain size regarding the sieve analysis test.
The size distributions of grains in the second group are composed regarding the NEN 2560.
The dominant particle size zone is defined as area in which the number of grains is considerably higher than the other grain sizes (Fig. 6).
This chart can be obtained from the number of grains which remain on each sieve during the sieve analysis.
Conclusions The results show that grading of the aggregates regarding their remaining mass on each sieve is not enough for representation of a highly poly disperse granular skeleton and that grading regarding the number of grains remaining on each sieve is also necessary.