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Sierra Leona 550, Lomas, 78210, San Luis Potosi, SLP, MEXICO robbierivas2002@yahoo.com.mx, cgomezy@ipn.mx, ialexvd11@gmail.com, jdjcr35@uaslp.mx Keywords: Mechanical activation, varistors, ZnO Abstract:Using Mechanical Activation it is possible to obtain small grain size and good homogeneity in a ceramic piece.
For ZnO varistor devices Mechanical Activation appears to be a good fabrication technique, since good homogeneity and small grain sizes are advantageous microstructural features.
Other important parameter that qualifies the performance of a varistor is the breakdown voltage, VR, which is related to the grain boundaries presented in between the device electrodes by the next expression [1,2]: VR= n Vg (2) Where n is the number of grain boundaries in between the device electrodes, and Vg is the breakdown voltage per intergranular barrier.
The expression 2, implies that the smaller the grain size the higher the breakdown voltage of the device.
It can be concluded hence, that small grain size and good homogeneity in the mixture are two key microstructural features seeked in a varistor in order to obtain good performance.

Thus cavity swelling and grain boundary brittleness are strongly influenced by existence of helium atoms [3,4,5].
Precipitates were observed in the matrix and grain boundaries, and they were identified as carbides by EDS analysis.
After irradiation grain boundary segregation was investigated by EDS analysis.
The grain boundary segregation is influenced by dislocation density or structure.
It might be said that grain boundary segregation is also influenced by cavity sink strength.

Introduction In the populous China, grain issue is related to national economy and the people's livelihood.
Annually, the domestic market has a million tons of grain circulation, while the international market has thousands of tons of grain circulation and export.
Grain’s impurities, mildew and pests will seriously affect grain quality.
In order to reduce losses and ensure food quality, it needs to accurately and effetely detect these parameters affected grain quality [2].
After selecting a group of independent continuous integrable functions fm (x, y) (m is any real number), a series of feature parameters Im of curve C on the characteristic function.

In 2009 and 2011, grains of the three varieties were sown in trays for wet seedling nursing in April.
Table 2 8 panicle related quantitative characteristics No. name of characteristics range of note C45 panicle: length 1-9 C59 panicle: number of grains 1-9 C60 spikelet: fertility 1-9 C64 grain: length 1-9 C65 grain: width 1-9 C67 grains: weight of 1000 fully developed grains 1-9 C70 decorticated grain: length 1-9 C71 decorticated grain: width 1-9 Table 3 Ranges of expression states of the 8 panicle related characteristics No. unit Note 1 Note 2 Note 3 Note 4 Note 5 Note 6 Note 7 Note 8 Note 9 C45 cm 0-5 5.1-10 10.1-15 15.1-20 20.1-25 25.1-30 30.1-35 35.1-40 40.1-60 C59 grains 0-30 31-60 61-80 81-100 101-150 151-200 201-250 251-300 301-600 C60 % 0-10 11-20 21-35 36-55 56-75 76-85 86-90 91-95 95-100 C64 mm 0-3 3.1-4 4.1-5 5.1-6 6.1-7 7.1-8 8.1-9 9.1-10 10.1-20 C65 mm 0-1 1.1-1.5 1.6-2 2.1-2.5 2.6-3 3.1-3.5 3.6-4 4.1-4.5 4.6-10 C67 g 0-11 11.1-16 16.1-20 20.1-24 24.1-28 28.1-32 32.1-36 36.1-40 40.1-90 C70 mm 0-4 4.1-5 5.1-5.5 5.6-6 6.1-6.5 6.6-7 7.1-7.5 7.6-8 8.1-20 C71 mm 0-0.5 0.6-1.1
Table 4 shows that all of the three varieties have different expression in characteristic of “panicle: number of grains”, and differences in “note” are always 1 grade, except characteristic of “spikelet: fertility” of variety A1.
It is clear that environmental changes can have significant impact on the expression of “panicle: length”, while variety factor have extremely significant impact on the characteristics of “panicle: length”, “grain: length”, “grain: width”, “decorticated grain: length” and “decorticated grain: width”.
Generally, variety factor are more influential than environment factor to the 8 characteristics except C59 (panicle: number of grains) and C60 (spikelete: fertility) (Fig. 1).

Deformation can occur only by slip in the basal plane, which offers a limited number of deformation systems.
Analysis of the structure of the alloy material showed that the structure is heterogeneous: large grains with extensive substructure within the grains can be found.
Average grain size is approx. 400 μm.
In the microstructure of all examined areas, fine recrystallized grains surrounded by larger grains were observed.
In the rod subsurface zone, the average grain size after the rolling is about 4.5 μm, whereas in the core of the rod grains are much larger - diameter of about 10 μm (Fig. 7c).

It was suggested that alloy stoichiometry strongly influences grain-boundary chemistry which in turn, affects the grain-boundary cohesion [10].
The Fe and Ni concentrations in grain interior and at grain boundary for the ordered Ni3Fe alloy were measured by Energy Dispersive X-ray Spectroscopy (EDS) mounting in TEM.
From Tab. 1, it can be seen that the Fe concentration in grain interior is almost the same as that at the grain boundary after considering the error of the instrument.
The Fe and Ni concentration in grain interior and at grain boundary for the ordered Ni3Fe alloy Sample Ni-18Fe Ni-22Fe Ni-25Fe Ni-28Fe site grain interior grain boundary grain interior grain boundary grain interior grain boundary grain interior grain boundary CFe , at.% 18.76 19.83 22.46 23.24 26.43 26.52 30.04 29.73 CNi , at.% 81.24 80.17 77.54 76.76 74.07 73.48 69.96 70.27 Figure 3 illustrates the stress-strain curves of the disordered and ordered Ni-18Fe and Ni-25Fe alloy when the tensile testing in vacuum.
If there is difference between the bond energy of Fe-Fe atom-pair (e Fe-Fe) and the bond energy of Ni-Ni atom-pair (e Ni-Ni), the numbers and kinds of atom-pairs will affect the tensile strength of Ni3Fe.

The coating without Y2O3 is mainly composed of a-Ti cellular dendrites and an eutecticum in which a large number of coarse and fine needle-shaped TiB and a few equiaxial TiC particles are homogeneously embedded.
A small amount of Y2O3 addition can refine the microstructure by transforming a-Ti grains from cellular dendrites to columnar or equiaxial crystals, and can increase the volume fraction of the reinforcements.
The transition from cellular dendrites to columnar or equiaxial crystals can be described as follows [6-8]: (1) Y2O3 particles with high melting point act as heterogeneous nuclei; (2) Y2O3 would make a dragging effect on the grain boundary movement and the grain growth would be suppressed; (3) Y2O3 can also decrease the critical nucleation work of primary b-Ti grains due to its high chemical activity.

Very fine grain size of about 4 microns was obtained in stir zone followed by elongated and rotated grains in TMAZ where dynamic recrystallization did not occur. 1.
There are a number of technologies available today that can form aluminum alloy joints, with varying degrees of final joint quality.
The grains were rotated in the direction of metal flow in TMAZ.
The grain rotation reached 90 degrees as seen from Fig. 13.
Dawes, “Improvements Relating to Friction Welding”, International Patent Classification 5, World Intellectual Property Organization, International Publication Number: WO 93/10935, (1993)

Structure of く-Mg17Al12 is body-centered cubic (bcc), its lattice parameter a=10.56 o A, it distributes along the grain boundary liking net or grown a larger particle on the grain boundary.
く-Mg17Al12 in composites is much less than in AZ91, whereas a number of metallic compound with Cu distribute as net in composites.
Amount of compound distribute along grain boundary with composition of Al31.72Mg42.6Cu25.68, so it is suggested that the reaction happened between the particle and metrix alloy.
Therefore, i-phase decomposed and new free Cu occur, Cu diffused into the matrix alloy and then combined with Mg and Al in the matrix became metallic-compound dispersing along the grain boundary.
Generally, because of the different thermal expansion coefficient between the reinforced particle and matrix alloy, a large number of dislocation and remaining hot stress were brought into composites, which improve the precipitation when ageing.

The error function per material point is then defined as ϕp=1Ni=1Nri(p), (4) where N is the number of time points.
To this end, the direct thermal model needs to be evaluated on a number of points in the parameter space to obtain the calibration points.
It can be steeply increased by reducing the grain size, but also with the increase in grain size, albeit not that rapidly.
This is repeated for different grain sizes.
(a) The Vickers pyramid hardness number for the reference cooling profile plotted against different grain sizes, and (b) the hardness values plotted for different cooling rates and different grain sizes, with the selected target hardness marked with horizontal and vertical spans Inverse analysis of the quenching operation.