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Fatigue tests with small dog-bone-shaped specimens were conducted under fully reversed axial loading (R = -1) with a constant stress amplitude and were interrupted when the first slip bands occurred and at defined numbers of load cycles, respectively.
Introduction Fatigue crack initiation in ductile materials depends on local plastic deformation and starts either at grain boundaries or at slip bands within a single grain.
Using the long distance microscope allows interrupting the fatigue tests when the first slip bands occurred or at defined numbers of load cycles, respectively (Figure 2).
Figure 2: Damage accumulation in a ferritic grain The surface topography of individual grains with interesting slip band formations was measured afterwards with a white light interferometer.
Even the slight height differences between grains can be illustrated.

With increasing number of cycles, deformation increases further, and the stress concentration of the twins cannot be released.
Fig.7 Low cycle fatigue life versus grain size is for IN718 alloy Under low cycle fatigue alternative load conditions, different grains have different slip system orientations, where in slip cannot continuously move from one grain to another grain.
The dislocation slip occurred before restarts, then dislocation moves from the grain and the crack extends from one grain to another grain.
During the crack growth process, the stress state at the crack tip and stress intensity factor are different, leading to a different active slip number and slip band.
Acknowledgments The authors would like to acknowledge the financial support of the National Important Base Research and Development Program of China under Contract Number 2010CB631203.

We defines the recovered fraction of aluminium grains as frc and the recrystallised fraction as frx.
Grain growth.
Also, krx points to the predominance of Al-Sn phase boundaries, while grain growth is characterised by the increase of Al-Al grain boundaries.
These results indicate that a model based on grain growth alone is not accurate.
However, even the simplest physically-based model tested here resulted more accurate than the polynomial fit, with a smaller number of adjustable parameters.

Again a similar microstructure was obtained when the B2O3 content was raised to 1 mol% except the number of abnormally grown grains was increased.
The 2mol% B2O3 addition resulted in a sudden grain growth with large pores trapped among the grains.
The fine-grained matrix attached on the large grain surfaces within the pore cavities can be clearly seen in Fig1c.
This phase can be seen as dark grains in the backscattered electron image given in Fig.1f, which arises from the lighter atomic number contrast of this Ti-rich phase compared to the matrix grains.
The addition of B2O3 above 0.5 mol% increases the grain size.

Natural gold microstructure results Mako QP’s gold microstructure is characterised by a bi-modal grain size, with small grains up to 100 µm in size and large grains over 200 µm in size (Fig. 1A).
The external shape of the gold grains is extremely irregular, regardless of size, whereas the high angle grain boundaries (HAGB) within gold grains are regular, either straight or curved (Fig. 1A).
The gold grains exhibit a preferred orientation of lattice bending (misorientation <2°, shown as changes in the colour inside the grain) and low angle grain boundaries (LAGB) <10° (Fig. 1A).
(A and C) Greyscale changes correspond to orientation changes of the gold grains (internally and between grains).
[7] Lloyd, G.E., Atomic-number and crystallographic contrast images with the SEM - a review of backscattered electron techniques, Mineral.

There are few Fe and Mn element in liquid alloy, limited number of small particles in the formed compounds is the reason for no grain refinement.
It is indicated that Mg-Al phase composition at the grain boundary changed.
Grain refinement appears, which is available from Fig. 3.
As shown in Fig. 2, TRT process led to the grain of sample No. 2 coarsening.
Consequently, grain refines the same as sample No.3.

The Comparative Effectiveness of Nb Solute and NbC Precipitates at Impeding Grain Boundary Motion in Nb-Steels Christopher R.
The recrystallization process (and the subsequent grain growth) largely controls the final grain size of the material and in alloys such as ferritic steels, this is the primary means to control the mechanical properties of the alloy.
A fine grain size can be achieved by maximizing the nucleation rate of recrystallization and minimizing the growth rate (or boundary migration velocity) during recrystallization and grain growth.
The solute drag effect, on the other hand, reduces the mobility of the boundary in a non-linear manner depending on velocity and depends on a number of parameters such as the binding energy of solute to the grain boundary (Eb), the diffusivity of solute across the boundary (D trans ) and the mobility of the boundary in the absence of solute (M0).
In both ferrite and austenite, a grain boundary energy, γ, of 0.6 J/m2 is used.

Macrostructure in the transverse (a), longitudinal (b) section of the tube, lining-out and Vickers hardness impressions (c) (without magnification) Analysis of the macrostructure showed that it is homogeneous in both the transverse and longitudinal section (Fig. 1, a, b) and has a 1-2 grain size number according to the grain size scale of the macrostructure of titanium alloys [15].
In these areas, grains elongated along the extrusion direction with 4th elongation scale number according to [8].
At the same time, the presence of a small number of elongated grains indicates that recrystallization processes are not fully completed.
This structure refers mainly to 2-3d structure scale number, according to the scale of microstructures of α-alloys [12].
This led to the formation of a more homogeneous and fine-grained structure with 1-2 and 2-3 structure scale number according to the scales of macro- and microstructures of titanium alloys, a two-component tangential texture (0001)TD<100>ED and (0001)TD<110>ED and hardness – 155 HV.

As a consequence, two fully-recrystallized material states with different grain size were obtained: fine-grained with ~10 μm average grain size (Fig. 4a) and coarse-grained with ~200 μm average grain size (Fig. 4b).
Microstructure of CuZn10, a) fine-grained alloy with ~10 μm average grain size, b) coarse-grained alloy with ~200 μm average grain size a) b) c) Fig. 5.
Upon the first minutes of the test prominent traces of plastic strain, grains uplifting and cracking along grain boundaries are visible (Fig.8 a-b).
A surface state of the CuZn10 after cold rolling and annealing at 750 ºC (a grain size of 200 µm), a),b) plastic deformation effects, c), d) the uplifting of grain boundaries zones, e), f) cavities and craters n the sample surface Additionally, results of the SEM microscopic observations revealed a large number of shear bands located near grain boundaries.
A large number of shear bands observed on surface of each sample indicate on a fatigue character of cavitational destruction. 3.

The microstructure of the material evolved during the process vary from columnar grain along the thermal gradient in the melt pool to fine equiaxed grains.
In their study, the number of Si particles were observed to have decreased with increasing solution temperature.
Material and Process Average Grain Size (μm) Hv0.05 LBPF Al [1] 6.0 ± 2 127 ± 1 FSPed Al 2.57 ± 1 64 ± 1 For specimens that underwent FSP, fine equiaxed grains were observed with significant grain refinements.
Recrystallisation and recovery of the material could have led to an increase in the number of sub-grain boundaries as observed in the EBSD images (Figure 3).
Material and Process Mean grain Misorientation Fraction of high-angle grain boundaries (>15°) Fraction of low angle grain boundaries (<=15°) Number of samples (1-5°) (0-15°) LBPF Al [1] 7.07 0.14 0.83 0.86 99709 FSPed Al 15.10 0.34 0.55 0.66 120740 Microhardness.