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Liu et al. [6, 7] reported structure, energy and transformations of graphene grain boundaries and their effect on failure strength.
It can be given as (2) where τ0=10-13 s is the average vibration period of atoms in solid; k is the Boltzmann constant; T is the temperature; γ=qV, where V is the activation volume and q is the coefficient of local overstress; U0 is the interatomic bond dissociation energy; ns is the number of sites available for the state transition; a and b are the material constant for NLE behaviour of graphene.
Chang, Structure, energy, and structural transformations of graphene grain boundaries from atomistic simulations.
Chang, Effects of dislocation densities and distributions on graphene grain boundary failure strengths from atomistic simulations.

In addition, it is very well suited for the SLM process that the maraging steel achieves its mechanical properties by a martensitic matrix that contains a high number density of nanometer-sized intermetallic precipitates, so it need to be quenched rapidly from the austenitic region to temperatures below the martensite start temperature.
An epitaxial growth of extremely fine cellular grains or dendrites across the hatchoverlap regions is observed.
These austenite grains are observed to nucleate on laths and parent austenite grain boundaries.

The peak at 1333 cm-1 relates to diamond, the peaks at 1355 and 1540 cm-1 correspond to the D and G bands [8] and the peaks at 1134 and 1478 cm-1 are ascribed to the presence of trans-polyacetylene (t-PA) at grain boundaries [9].
Figure 2 shows the SEM image of the pristine MCD film surface and coefficient of friction (COF) versus number of sliding cycles.
The MCD film consists of diamond grains up to 2 µm in size.
De Barros, Deposition, structure, mechanical properties and tribological behavior of polycrystalline to smooth fine-grained diamond coatings.

In particular, HU is negative in the pH range 4-5 and positive at pH higher than 6 which is consistent with a dominant fraction of grains having (a) the c-axis perpendicular (HU <0) and, (b) the c-axis parallel (HU >0) to the wires axis.
As can be observed, by changing the current density from 50 down to 5 mA.cm-2, the resonance field can change as much as 8 kOe, which is consistent with a dominant fraction of Co hcp grains having their c-axis perpendicular (high current) and parallel (low current) to the wire axis.
Although only short sections (~100nm) of these wires are shown in the images, no grain boundaries were observed along longer sections of the ten wires that have been examined in detail.
Another possible reason for the reduction of HU are stacking faults, which might increase in number in the high pH samples.

The result is a growing number of components produced from different titanium and aluminum alloys for aerospace applications in particular, in addition to a greater interest to utilize the technique in automotive and medical applications.
� Simple constitutive equation (Eqn. 3), which does not account for many features associated with superplastic deformation, like strain hardening, anisotropy, grain growth and cavitation [4, 9-11, 13]
Microstructure is accounted for by the grain size (d) and cavitation by correcting the stress value to account for the area fraction of voids.
The model accounts for microstructural evolution (grain growth and cavitation), strain hardening and variable strain rate sensitivity index m.

The increasing grain size with depth leads to progressively more irregular and less-well-defined positions of the diffraction lines.
This problem was partly solved by using an in-plane sample oscillation (+/- 5mm along the axis) during the measurement, in order to increase the sampling of the reflecting grains, thus allowing a more accurate determination of the peak position.
The total number of parameters {aj} to be optimized in the data modelling is nine: six polynomial coefficients and three coefficients related to the Bezier curve.
At increasing depths (b), data dispersion increases, especially when exiting the layer plastically deformed by the shot-peening (c), and grain size becomes too large to provide the correct statistics to the XRD measurement.

Table. 2 Tensile strength of specimens under different conditions Samples number Tensile strength [MPa] Yield strength [MPa] Elongation [%] Casting alloy 350 205 13 No. 1 563 450 18 No. 2 635 505 19.5 No. 3 460 375 12.5 XRD analysis.
After the cold rolling processing, we also observe that there are many nanoparticles with diameters in the range from 2 to 20nm in the matrix, the dispersal nanoparticles can pin the sub-grain and dislocation, the yield behavior of the alloy is determined by the configuration of dislocation in the copper matrix and its interaction with the dispersal nanoparticles.
In the melt solidification process, a possible reason is that iron nanoparticles may act as nucleating centers during the solidification of the copper matrix, then lowers down the critical nucleation energy, raises the diffusion activation energy and nucleation rate, resulting in a decreased dimension of the grains of the copper matrix.
It is noted that the energy system of Cu-Sn-Zn-Fe-Co alloy with plastic deformation is in the high-energy state, when taken ageing at 673Κ for 4h, the tin element diffuses into the copper matrix through the high diffusion rate passageway (such as the high density dislocation, grain boundaries, phase interface).Hence the segregation of tin element in the copper matrix and the existence of hard and brittle phase eliminate, the disappearance of these benefits to improve the strength of the alloy.

The interpretation of the Me-atom self-diffusion is difficult because of the unknown grain boundary contribution to the total diffusivity and rather high temperatures.
We define the formation energies of single point defects as: (3) (4) where is the formation energy for the carbides (-1.79 eV/f.u. for TiC and –1.77 eV/f.u. for ZrC), N is the number of MeC formula units per supercell, and REF denotes the reference state of pure Me (hcp) or C (diamond structure).
This contradiction may indicate that in one of the experiments reported in [4] the contribution from grain-boundary diffusion was higher than in the other.
Grain-boundary contribution usually results in a higher value and a lower activation energy value.

The absence of reflections from aluminum on a diffraction pattern suggests that the aluminum film grew fine-grained (Fig. 4а).
It must be noted that in a number of works the crystal structure of the Ni2Al3 phase is considered as the B2 NiAl phase with the ordered arrangement of constitutional defects on the B2 underlying the lattice [19]. 25 35 45 55 65 75 85 2Θ (deg.)
Microstructure of multilayer and heterogeneous alloys consists of grains with different composition.
At temperatures of the phase transformations the intensive processes of intermixing, structural reconstruction, and phase formation occur at grain interfaces.

Sample Annealing temperature FWHM Lattice parameter (A) Grain size D(nm) Dislocation densi4y (δ) × 1014 (lines/m2) 1 4000C 0.7804 a= 4.170 11.25 79 2 4500C 0.7628 a=4.170 11.51 75 3 5000C 0.7073 a=4.805 12.38. 65 Grain size was calculated the following equation.
The grains can be found in a variety of patterns with approximately the same proportions.
The films transmission and absorption are affected by the number and speed of dipping and annealing temperatures.