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The results showed that the iron-rich phase in aluminium alloy is a large number of alpha - Al3Fe and a small amount of lambda - Al13Fe4; the rich iron phases are distributed in aluminum alloy substrate in three-dimensional space, and its metallographic appearances in different sections present sheet, plate and needle-like structure.
The reason may be when the iron content was low, Fe vacancy concentration became higher, and the increase of the number of Fe vacancies or the increase of the number of Fe vacancies occupied by Al in FeAl3 crystal, led to the decreases of crystal lattice, with the increase of iron content Fe vacancy concentration became lower and lower, so that the lattice constant was closer to standard values, and finally stabilized.
In Figures 4(b), the lattice plane angle of the two A {101} is about 81.1°, matched with the tetragonal FeAl3 grain observed along crystal zone axis[111].
Therefore, it is concluded that the grains at the lower right corner are Fe4Al13.
(2) The iron-rich phases grow along the grain boundary of aluminum alloy, exhibiting a three-dimensional distribution; its appearance morphology is not sufficient as a criterion to identify different iron-rich phases

The reduction of carbon content is the main factor in improving weldability and toughness of the coarse-grained HAZ.
In the coarse-grained zone, most particles from microalloying elements (except for possibly TiN) are dissolve.
There are quite a number of models which try to predict the maximum hardness in the HAZ from knowledge of steel chemistry and welding condition.
Elements that act to refine the grain size have a positive influence on toughness.
Boron can suppress the austenite/ferrite transformation by segregating to the austenite grain boundaries.

M is the mean Taylor factor all over the grains ( 06.3=M for a fcc structure without texture).
In fact, transmission electron microscopy results [2,3] show that after 25% strain in tension only a few grains present twinning and its contribution for deformation in those grains is less than 2.5%.
In Table 1 are also shown the correspondent parameters at the grain scale.
Sometimes, two twinning systems are active in distinct regions of the grain.
The present results also explain previous experimental results, particularly the sharp decrease in the work-hardening ratio versus stress curves and the fact that the number of twins increases with strain quicker in tension than in rolling.

With the increased frequency pulse, the modified depth increased (Fig.5(c)), the average melting depth (white light melting layer) is still 2 ~ 3μm, the maximum melting depth (the depth of crater) is about 8μm, the surface around the following 30 ~ 40μm range (the arrow positions), grain refinement and microcrystalline, nanocrystalline structure formed even amorphous structure and distribution of a large number of needle-like organization which is the needle martensite by analyzing.
Grain size of the original sample was 380.7 (A), the size of the grain size after the 8 times pulse treatment was 290.2 (A), the size of the grain size after 15 times pulse treatment was 248.7 (A).
Fully analyzed, in the case of smaller pulse number , with the increase of pulse frequency, the surface carbide dissolution, the residual austenite content increased, grain size became smaller, more uniform and dense tissue.
The number of bombardment increased, energy deposition increased, surface melting and recrystallization more intense, grain more refined, decomposition and restructuring of the organization, as well as combination of the elements between the high temperature into a new organization and structure, these were all play very active role in improving surface corrosion resistance.
The first step, in the range of 1~7 pulse times, can be assigned to the expanding of melting zone and crater number.

The method is very suitable for aerospace industry which produces parts in limited numbers.
After cooling, the samples were tested for hardness and grain size control.
The size of grain affects mechanical properties of the material significantly.
Grain size changes with respect to various processing methods were studied.
Rapid heating process did not change grain size considerably.

Introduction A number of fluoride, chloride and plutonium containing wastes arising from pyrochemical reprocessing of plutonium require to be safely immobilized at AWE.
Apatite was chosen for immobilization for a number of reasons.
At compositions where x ≤ 0.125, micrographs showed a number of hafnium rich grains, approx 5µm in size, in addition to the main fluorapatite phase.
EDS elemental maps (Fig 5b-d) indicated that these grains were hafnium rich and, compared to the surrounding apatite phase, deficient in both calcium and phosphorus.
However a small number of HfO2 grains were also visible on SEM images at x = 0.125.

In order to obtain good properties, study on the effect of sintering profile was preferred because it can control the grain growth which contributes to the final phase present.
The grain growth can be controlled by two approaches; one is to prohibit grain growth by addition or dispersion of a second phase particles, the other is to control grain growth by a heat treatment processing method.
It was first reported that a two-step sintering technique could be also used as an efficient route to attain a homogeneous microstructure and to decrease the number of closed pores [3].
The two step sintering is an approach to control grain growth that usually occurs during the final firing stage [4].
However, in sample 2s the samples were holding at 865 °C for 20 minutes to control the number of nucleus.

The EBSD measurements data were used to analyze the local grain orientation, the grain size and the grain boundary character distribution.
Large number of boundaries falls into the range of below 10° in misorientation angles in all these samples.
Fig. 3 shows the effect of cooling rate on high-angle grain boundaries (HAGBs) (θ≥15°) and low-angle grain boundaries (LAGBs) (2°≤θ<15°).
Fig. 3 The fraction of low-angle grain boundaries (LAGBs) and high-angle grain boundaries (HAGBs).
Fig. 4 represents the grain size distribution with the variant tolerance angles.

Figure 2a (see area marked with oval) shows an austenite grain nucleated on the ferritepearlite grain boundary.
In this grain the cementite plates are still visible and in some cases partially dissolved.
The arrows indicate the nucleation of austenite at the triple point (a) and the ferrite-ferrite grain boundary (b).
The second interesting observation is related to the nucleation of austenite on the ferriteferrite grain boundaries: at a triple point (see arrow in Fig. 2a) and a grain boundary (see Fig. 2b).
Numbers in brackets correspond to figurative points (1)-(5) in Fig. 3,4.

The cavity growth is controlled by grain deformation and the coalescence of cavities.
When the10% grain boundaries are occupied by cavities, the assumed ruptures occur [15].
According to the experiment reported by Rauch et al. [17], a significant number of cavities were observed at low stress level.
The number of creep cavities per area increases with the creep damage process and the highest density of creep cavities is located in the mid-thickness (or the center of the fine-grained heat-affected zone) region which is about 60% creep damage rather than the surface region of the fine-grained heat-affected zone [18, 30-33].
The creep cavities have already nucleated on grain boundaries at less than 25% creep damage [35].