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In the view of optical metallography, these products of the coarse-grained h-ferrite decomposition had similar morphologies to those of the coarse-grained け decomposition in a typical alloy steel weld metal [5].
This peculiar morphology of the embedded h-ferrite island results from a number of particles of the intragranularly nucleated austenite growing closely together.
The results for 5 pairs of austenite grains are presented in Table 2.
It should be noted that the grains of intragranulaly nucleated austenite can appear to be adjacent to one another for two different circumstances: the formation of one grain may stimulate the growth of another or grains which have nucleated at completely separate sites may come in contact as a consequence of impingement.
Number Axis angle pair 1 [-0.1924 0.9623 0.1925] 180fl 2 [-0.9392 -0.2855 0.1906 ] 179fl 3 [ 0.0823 0.6175 0.7822 ] 180fl 4 [ 0.6886 0.0521 0.7233 ] 180fl 5 [ 0.6998 0.0213 0.7140 ] 180fl

The material was selected because of its grain size which is of the order of 1 µm.
The observed crack shapes are shown in Fig. 3 for three different numbers of fatigue cycles.
This is a direct consequence of the small grain size encountered in this material.
From the K=f(θ) curves, and the experimental values of the crack size at different number of cycles, da/dN=f(∆K) and dc/dN=f(∆K) curves could be obtained.
For Al alloys, it has been shown that fatigue cracks with a size comparable to the grain size exhibit an irregular crack front which is caused by the presence of grains which impede or promote crack propagation.

Six different numbers of elements are used to discretise the core area, and the deviations to the maximum PSED values are shown in Fig. 2.
As can be seen from the figure, the PSED value increases with the increase of the number of elements, and converges (< 1%) when the number of elements exceeds about 86,000.
The main feature of the proposed CPFE model is that it takes the size, shape and orientation of individual grains into account, as compared with the traditional CP model which assumes all elements consist of a number of grains representative of the overall texture of the material.
No particular treatment is applied to the grain boundaries, thus the grain boundary effect is entirely caused by the different crystalline properties of neighbouring grains.
Deviations of the plastic strain energy density with increase of element number.

(a) Parallel arrangement of grains (shaded) and grain boundaries in the diffusion direction; (b) Series arrangement of grains (shaded) and grain boundaries in the diffusion direction; (c) Grains represented as cubes (shaded).
For other arrangements and shapes of the grains, there have been a large number of different formalisms that have been developed that attempt to describe the effective diffusivity.
Substituting the electrical conductivity with the diffusivity assumes, in effect, that the numbers of charge carriers per unit volume in each ‘phase’ are equal.
The extent of this access depends on the concentration of grain boundaries, the relative values of Dgb and Dl and the solubility limits of the solute between the grains and grain boundaries.
In other words, an average tracer atom will explore a number of grains in the diffusion time.

In homogeneous nucleation, the total number of nuclei can be obtained from the classical nucleation theory.
For a given volume of steel (V), the grain size (d) and the total number of nuclei (N) has the following approximation
Each lattice point is assigned an identification (ID) number to represent its physical state.
To nucleate M number of martensite plates with all 24 variants in equal opportunities within an austenite grain, The random number x () is called and checked if its value falls into the range of (i=1, 2, … 24).
Martensite is nucleated at either martensite grain boundary or around a inclusion within the austenite grain.

Grain size, texture and strain rate jointly affect the deformation mechanisms.
The lowest processing temperature was 388K, and the average grain size was ~370 nm.
reason that the fine grain had just began to generate around the coarse grain due to severe plastic deformation of ECAP progress.
What’s more, finer grain size leads to more grain boundaries which will block the move of the dislocation as slip metamorphosing and that will increase the resistance of plastic deformation.
The average misorientation angle increases as the increase of the pass number and that will result in the easy appearance of extension twinning under compression load.

The grain boundary is ambiguous, and α-phase grain occur fusion, merger and adhesion.
At this time, the grain growth mechanism becomes Ostald growing up, that means large grain grows, and small grain gradually decreases even melts.
And the grain boundary is relatively clear, with a fine grain size of an average diameter of 48.3um.
When the isothermal holding time is 10min (Fig.3b), grain size and morphology have taken place great changes, some small grains melt away, other grains combine each other and grow up, and the grains are round, with the average size of 58.1um.
It can be seen from above comprehensive analysis that during the initial stage of isothermal holding, the grains grow faster, with time goes on, grain growing speed slows down, and the number of small grains reduces, the grain size also becomes smaller and smaller or even completely melted.

For example, one can investigate the grain size due to deformation in a metal.
The electronic circuitry measures the number of events vs. the delay time between the start and stop signals 2-2.
More detailed measurements of e+ annihilation on fine-grained ZnAl alloys as a function of the mean grain size were also reported by [12,13].
For large grain sizes, the mean lifetime t varies linearly with the inverse grain size l-1, in agreement with most of the available experimental data [13].
The comparison of observed‘d’ values with standard ‘d’ values (PDF number 04-0787) indicates that the 5251Al samples are polycrystalline and have face centered cubic structure.

Subsequently, the grains were refined and became tiny grains under the action of a large number of edge dislocations in the crystals.
Therefore only the big grains were left after 30 minutes of irradiation. 1.
In this area, the grain size of BP is about 20-50nm.
Finally, only the large grains were left in Fig. 5 (b) after 30 minutes of irradiation.
(3) The morphology of the crystal showed that the amorphous phosphorus turned into large size BP nanocrystals under the action of mechanical milling and then, upon being refined, became tiny grains under the action of a large number of edge dislocations.

Grain refinement is expected to promote significant enhancement in both properties.
This number is expected to double between 1999 and 2025 as a result of aging populations worldwide and growing demand for a higher quality of life. [9] Another statistical data estimated that by the end of 2030, the number of total knee arthoplasties is predicted to grow by 673% from the present rate [10].
Achieved by optimizing grain flow characteristics during forging process, the ability to tailor this directional strength permits forgings to meet different performance requirements for an almost unlimited number of part configurations [8].
A representative bright-field TEM image of the grain structure of CoCrMo alloy is shown in Figure 3 (a).
The forging step done only once and resulted in positive findings on the grain structure of the alloy.