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Besides the intrinsic CMR effect, grain boundary in polycrystalline samples plays a significant role on the MR [4, 5].
Recently, a number of groups [6, 7] have disclosed that compositing materials of good electrical conductivity with perovskite manganite can enhance the room temperature MR if TC of the compound is near room temperature.
With increasing IrO2 content to high concentrations, x≥0.25, some part of the IrO2 goes inside the grains substituting Mn in the LCSMO lattice and the remainder goes to the grain boundaries.
The resistivity decreases with IrO2 addition, which indicates that the influence of grain boundaries is dominant.
In this composites system, when the doping amount up to a certain extent, the DE effect were seriously damaged and a large number of anti-ferromagnetic coupling were produced in the materials, the adverse effects of IrO2 is dominate which made the MR to decrease.

- Replica R5 shows ferrite, globular perlite and coarse inter-intragranular precipitation with few grain boundaries
In essence, the number of intersections between the grid and the grain boundaries were measured.
The formulas applied for the calculation of grain boundary degradation are presented below equation (1) and (2): di = SOnO+SVnV2, where i = 1 … N (1) D = 1-did1⋅100% (2) d1 - weighted average of the sum of intersections for unused material (i = 1); di - weighted average of the sum of intersections for degraded material; N - natural number; SO - the sum of the intersections in the horizontal direction; SV - the sum of the intersections on the vertical direction; nO - number of measurements in the horizontal direction; nV - number of measurements in the vertical direction; D - degradation of grain boundaries.
The method of measuring the grid intersections used with the grain boundary is explained in fig. 2 and 3.
In this case, by the non-destructive method of metallographic replicas, an extended service life of the component was estimated with a small number of 10225 operating hours.

SEM micrographs of the two sialon compositions (Fig.2) show a microstructure with a bright phase with an equiaxed grain morphology that corresponds to α-sialon and dark grains with elongated morphology corresponding to β-sialon.
The small bright spots are rich in Neodymium and represent the small fraction of amorphous grain boundary phase located at triple junctions.
Especially for materials with such a large crack growth exponent n the number of spontaneous failures during load application and survivals is larger than the number of tests with regular failure.
Before this stress level was reached, a number of 5 specimens failed spontaneously.
The large number of spontaneous failure and survivals made the development of a modified procedure necessary in order to obtain a significant database.

[1,2] A large number of applications of these alloys are in plate/sheet form or rod/pipe and their properties are strongly influenced not only by the microstructure such as phase distribution ,grain size, but aslo by the texture present in these materials. while ,most research about this kind of double phase titanium alloy have always focused on Ti–6Al–4V , few reports paid attention to Ti-4Al-1.5Mn alloy , in spite of this, the studies on this alloy have always been on plate/sheet .
The present study is aimed to investigate the microstructure including phase distribution, recrystallization , grain size,twin grains and the texture type of the recrystallized Ti-4Al-1.5Mn alloy .
Their respective average grain sizes were approximately 20μm and 5μm.
Fig.1(b) shows EBSD image quality (IQ) maps in which the grain boundaries was darker .It is found that β phase distributed both in the grain interior and the grain boundaries, The IQ map quantifies the sharpness of the Kikuchi pattern at each point and is similar to an OM(optical microscope) image with the difference that and the magnification was much bigger.
The mean α grain size of Ti-4Al-1.5Mn alloy is 23μm.

Also, temperature rise during hot forging could lead to the grain growth assisted with strain.
(b) (a) Journal Title and Volume Number (to be inserted by the publisher) 3 matrix.
The left part of section in Fig. 6(b) shows the large elongated grains with the size of tens of mm, which is likely to be originated from the coarse grains on the skin of the extruded stock and the deformation assisted grain growth during forging process.
Texture and particle characteristics on the grain boundaries could be also related with this abnormal grain growth by assisting a grain boundary movement in a certain direction.
The small grains in the middle section are not clear whether they are the recrystallized grains or not.

AZ31 Billet Homogenize Billet temperature /℃ Extrusion speed (m/min) Extrusion ratio Container /℃ Mold temperature /℃ 1 Cast 390℃,9h 380 2.5 20 380 420 2 Cast 390℃,9h 350 2.5 20 380 420 3 Cast 390℃,9h 300 2.5 20 380 420 4 Pre-extruded No 350 2.5 17 330 420 On the other hand, the pre-extrusion helps to enhance the density of vacancies, dislocations and other structural defects in the billet, increase the lattice distortion energy, upgrade the degree of deformation and quantity of grain boundaries and sub-grain boundaries, making the recrystallization nucleation rate and the number of grain boundaries increased when the second extrusion of magnesium alloy was carried out.
When the extrusion temperature is 300℃, the grain of profiles is smaller.
When the extrusion temperature reaches 350℃, tensile strength of the profiles decreases as a result of grain growth.
When the extrusion temperature reaches 380℃, the grain continue to grow.
In addition, compressional deformation makes the magnesium alloy grains elongate and produce straight grain boundaries. when the angle of tensile stress direction and straight grain boundaries is found to be 45o , the material exhibits a characteristic of low yield strength and high elongation, which is reflected on the mechanical properties of the cross-section of sidewall.

This process can yield not only the dense material structure and desirable grain flow strengthening, but also a higher production rate, better unitization of material, and lower operation cost [1-2].
The grains were distributed as a flow line pattern along the spline, which resulted in a fine and long fibrous state and the hardness on the section was distributed regularly [6].
The larger number of teeth could prolong the tool life and enhance the forming efficiency.
(a) Rod diameter = 6.4 mm Cross-sectional area = 32.17 mm2 Number of teeth = 27 (b) Rod diameter = 5.6 mm Cross-sectional area = 24.63 mm2 Number of teeth = 23 (c) Rod diameter = 6.0 mm Cross-sectional area = 28.27 mm2 Number of teeth = 25 Fig. 4 Profiles of micro-teeth components obtained by numerical simulation.
Due to the refinement of the grain structure, the mechanical strength of the profile-rolled teeth was improved by an average of 40%.

With the decrease of, the cluster of user accounts performs from fine-grained to coarse-grained, and finally a dynamic fuzzy cluster sequence of user accounts is obtained.
Obviously, the clustering result using narrow sliding window is more fine-grained, since it has larger number of clusters.
It also proves that by increasing/decreasing the width of sliding window appropriately, we could obtain coarse/fine-grained clustering result.
Whenincreases, the accuracy of model with 5 width sliding window drops faster than the other two, since it has more fine-grained fuzzy clustering result。
(a) The number of clusters (b) The average size of clusters (c) The accuracy Fig.3.

During superplastic deformation (SPD) of tetragonal zirconia polycrystals containing 3 mol% yttria (3Y-TZP) at high strain-rates, a number of crack-like flat cavities having very narrow gaps lying along grain boundaries mostly normal to the tensile axis are produced in addition to conventional cavities.
This would be caused mainly by the deformation induced concurrent grain growth.
Note that under the high strain-rate condition, almost no grain growth occurred.
Grain-boundary Crystal grain Flat cavities Now, a result of thermal expansion measurements has suggested [12] that an average width of the gaps each flat cavity has is within a few nanometers.
This fact suggests that as the holding time is increased, number of surviving flat cavities is reduced.

Grain refinement by severe plastic deformation (SPD) holds a special place among the techniques used for that.
The average grain size in this condition was 61.3 ± 5.9 μm.
A small amount of this phase can be observed at the grain boundaries, mainly at triple junctions of the grain boundaries.
A decrease of the swaging temperature led to further grain refinement and a more dispersed structure.
The large number of grain boundaries that play the role of barriers that inhibit the development of pitting corrosion, which is characteristic for magnesium alloys, can be a second reason.