Search results

The blue arrow represents SRX grains in austenite (Figure 5(c).
It is also proposed that smaller step size or larger EBSD image area could provide better understanding of microstructure (as the number of grains were limited in Figures 5(b), (b) and (c)).
The SRV grains of ferrite are shown in Figure 6(c).
However, the microstructure after 20 min of PDA showed coarsen austenite sub-grains, which were larger than as-deformed sub-grains by 4.69 µm (Figure 9).
Fig. 9: Plot of sub-grain size with PDA time for EQ- DSS.

Results show that, using SPS technique can prepare W-26Re alloy with high density, fine grain and excellent mechanical properties.
The (W) matrix grains were polygonal.
We can observe a large number of spherical holes existing in the matrix.
The W-26Re alloy with fine grains prepared by SPS did not obtain good ductility.
The alloy obtained high strength by fine grain strengthening and second phase strengthening.

Analysis of the surface residual stress in grinding Aermet100 Y.Q.Xu1,a, T.Zhang1,band Y.M.Bai1,c 1School of Mechanical & Electronic Engineering, Northwestern Polytechnical University, Xi’an Shanxi, 710072, China ayngqngxu@nwpu.edu.cn Key words: grinding, residual stress, grain Abstract: Grinding induces residual stresses, which can play an important role on the fatigue of the component.
In general, residual stresses in a ground surface are primarily generated due to three effects: thermal expansion and contraction during grinding, plastic deformation caused by the abrasive grains of the wheel and phase transformations due to high grinding temperature.
Secondly, the plastic deformation caused by the abrasive grains of the wheel was simulated base on the grain-workpiece interaction.
Based on a large number of experimental data and analyzed using regression equation, x=0.86,y=0.44,z=-1.06 in present study.

The grains of titanomagnetite are interspersed into gangue minerals mostly containing clinopyroxene and apatite.
The mass content of the gangue minerals significantly exceeds the number of the grains of titanomagnetite that excludes processing of the ore by the existing technologies.
Under equal experimental conditions iron in various grains of titanomagnetite was reduced by different ways.
Whereas, in the titanomagnetite grains surrounded by pyroxene it was reduced to metallic iron (Fig. 2, spectra 14).
- The reduction of iron in the grains of titanomagnetite surrounded by the apatite phase was worse than in the grains surrounded by the clinopyroxene phase.

The impedance spectrum of Gd sample indicates that both consist of semiconducting grain and moderately insulating grain boundary regions.
Generally, the formula of doped bismuth titanate is (Bi2O2)2+(Am–1BmO3m+1)2– , where A means mono-, di-, or trivalent ions, or a mixture of them; B means quadri- or quinquevalence ions, such as Ti4+, Nb5+, Ta5+; and m means integer number > 1.
Gd-doped sample exhibits randomly oriented and plate-like grains, of which the average grain area of Gd-doped sanple was approximately 5×5μm2, and thickness was less than 2μm in general.
In general, the capacitance C of grain and grain boundary are typically of the order of pFcm–1and nFcm–1, respectively.
The room temperature data therefore indicate Bi4-xGdxTi3O12 ceramics consist of moderately insulating grain boundary regions with semiconducting grains.

If the new grains of the matrix are formed through cold welding, the particles would be at the grain boundaries, but if the new grains are formed through dynamic recrystallisation, the particles may be distributed at both grain boundaries and inside grains, depending on whether the growing grains engulf the particles.
• Accumulation of a large number of fracturing-cold welding combinations.
For phases with low or zero ductility, combination of fracturing and cold welding might be important in increasing the number of grains and thus decreasing the grain size to nanometer scale.
It is clear that with a given ball size (reflected by ball weight shown in the graph), the calculation can predict the optimum number of balls for effective milling.
The results of the modelling work indicate that the selection of the number of balls should not simply be based on ball to powder weight ratio.

Fig. 2 indicates the growth of grain size at different heat treatment temperatures.
The micrographs from Fig. 2 were used to determine the average grain size number.
HT1000 recorded the fine grain size which is 71.8 µm, followed by HT1100 and HT1200.
The grain size for HT1100 and HT1200 are 89.9 µm and 124.4 µm, respectively.
Increasing the heat treatment temperature was increased the grain size. 2.

The error in measuring the orientations via the Hough transform method depends on a number of factors, particularly the diffraction pattern quality, and is typically ~1-2o [10].
The angular resolution depends on the pattern quality and the number of pixels in the camera, and can be as low as ~0.01o [12,13].
An EBSD map of a grain in the single-phase alloy, is shown in fig.1.
EBSD map of an “S” oriented grain in 0.25%Sc alloy containing 10nm particles.
Also, the larger misorientations are not reflected in the mean value because of the large number of very small misorientations.

High temperature mechanical properties of Si3N4 - SiC nanocomposites have been studied during last five years by a number of authors [5-7].
The Si3N4 - SiC nanocomposite consists of a very fine, homogeneously distributed Si3N4 grains with a low aspect ratio.
The composite contains additionally globular nano and submicron-sized SiC particles located intergranularly in the Si3N4 grains (the average particle size approximately 40 nm), or intragranularly between the Si3N4 grains Fig. 1.
SEM microstructure of plasma etched nanocomposite a) and grain size (diameter) distribution of the Si3N4 grains b) (the average particle size approximately 250 nm).
The average Si3N4 grain size (diameter) is below 140 nm and grains with a diameter larger than 500 nm occur in the microstructure only occasionally.

It could be seen that the particles consists of great number of aggregated nanosized subparticles with size below 100 nm.
The green body sintered at 1050ºC for 4 h (Fig. 9) had the grain size ranging between 400 - 500 nm.
The average grain size was further decreased to 215 nm with a decreasing the time of sintering to 45 min (Fig. 10).
The samples sintered at 1000ºC for 2 h had a higher porosity, but according to SEM, the grain size was below 200 nm (Fig. 11).
Microstructures of HAP compacts sintered at 1000°C, 1050°C and 1100°C were composed of uniform grains.