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The grain became more minute quasi-equiaxed as 15㎛ when 1Mo and 0.5Hf were added to Fe20Al6Cr (fig, 2(c)), the grain became the most minute quasi-equiaxed as 116㎛ when 1Mo and 1Hf were added(fig, 2(d)).
Therefore, the effect of adding Mo and Hf for being minute of grain refining was shown 0.1 Hf 〈0.5〈1.0.
In the case of superlattic peak, plane index is an even number and is showed in an odd number (example (200)s, (222)s) which was resulted when the sum total of plan index was divided by two.
The basic peak is shown in an even number, (example, (220)F, (400)F) which was resulted when the sum total of plan index was divided by two.
This increase of the rate of yield strength can also raise the precipitation hardening when the precipitated material of the second phrase is precipitated not only in grain but also grain boundary.

It is observed that there shows no evidence of reentrant grain flow, and the grain structure of both in the a) b) Fig.1 Optical micrograph of the alloy forging along the thickness: (a) T/2, and (b) T/8.
And in addition to aging precipitates inside grains and on the grain boundaries, there are special coarse precipitates inside the grain in the forging.
In the grain boundary map, coarse blue lines represent high angle grain boundaries (>15°), fine green lines (5~15°) and fine red lines (2~5°) represent low angle grain boundaries (2~15°).
A large number of size grains with high angle boundaries in big size elongated grains shows that the small size grains may be recrystallized grains, which are dominant in the core (T/2) of the alloy forging (as shown in Fig.4(a)).
The grain boundaries of recrystallized grains are as the weak interface, they are easy to become the path of crack propagation, which seriously affect the elongation and fracture toughness of the alloy forging.

From the Vickers hardness test of base metal, weld metal and HAZ, the hardness numbers of each specimen were obtained.
This is indicated by the shape of the fracture surface of the sample which is not flat, which means that the fracture does not cut the grain but follows the grain boundary.
numbers 1, 2, 3 are the base metal area on the left, while numbers 4, 5, and 6 are in the HAZ area, then numbers 8, 9 and 10 are in the Weld area.
Meanwhile, numbers 11 and 12 are the the right HAZ area.
And finally numbers 13, 14, 15 are the right base metal area.

To this end, large grained material was examined using EBSD (Electron Back Scattering Diffraction) in order to determine the relative crystalline orientations of the grains.
The SIMS technique is known to be sensitive to iodine but there are a number of issues that require being solved before the effect of temperature or oxygen potential may be quantitatively determined.
Comparison of depth profiles prior to and following annealing is possible since depth profiles are characterised under identical primary beam conditions and also because the analysed area corresponds to a statistically representative number of grains.
The EBSD cartography of the Cr-doped sample used for the analysis is reported in fig. 2a: each colour corresponds to a given grain orientation (i.e. direction of the grain normal vector).
ü Cr-doped sample analysis appears to indicate that the grain dependent sputtering rates are correlated to grain orientations.

The CR series has finer grains in comparison to the Untreated series.
Nitriding at 700 oC coarsened grains of CP titanium and average grain size of the CR+N700 series was 24 μm.
On the basis of the EBSD analysis, normal grain growth with recovery occurred in the cold rolled CP titanium during the nitriding process because each grain boundary had equivalent degree of mobility in the highly strained materials [9], resulting in the formation of recrystallized texture with fine grains in the CR+N600 series.
This was because the cold rolling refined grains of CP titanium.
Acknowledgement The authors would like to thank for Grant-in-Aid for Young Scientists (B) (JSPS KAKENHI Grant Number 24760090).

N= turn number.
N= turn number.
N= turn number.
N= turn number.
N= turn number.

The number of cycles was 36. [4] Cross-sectional TEM specimens were fabricated using a focused ion beam (FIB) mill with a microsampling unit.
The lower is composed of isotropic Nd2Fe14B grains, the middle one has a columnar structure of rectangular Nd2Fe14B grains about 2-3 µm in height and 1 µm in diameter, and the upper one is again composed of small isotropic grains.
However, the size of the Nd2Fe14B grains in each layer differs largely from that of the IDM films, respectively: Isotropic Nd2Fe14B grains in the lower layer are of 50-300nm in diameter, columnar grains in the middle layer are of about 1µm in height and 300nm in diameter, and isotropic fine grains in the lower layer are of several ten nm in diameter.
Micro-crystalline Nd2Fe14B grains are formed randomly on the layer of the columnar grains. 4.
At the first, isotropic grains are formed, but only the recrystallized grains suitable for the growth direction can keep growing up, and then an aggregate of columnar grains are formed to be the middle layer.

It seems that a crack in the range of low growth rate prefers to propagate along the grain boundaries under hydrogen environment while in the range of high growth across the grains accompanied by brittle striation patterns or river patterns.
In the low fatigue crack growth rate, hydrogen enhances the crack path near the grain boundary.
Although the fatigue crack propagates along the grain boundary, it does not occur at one cycle.
Moreover as we can observe the slip behavior near the grain boundary, even the intergranular crack may be influenced through the slip behavior by hydrogen.
( Δεt =0.80 % , 0.1 Hz) 0.1 1 10 10-10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 Crack growth rate dl/dN [m/cycle] Crack length l [mm] In H2 0.8% 0.1Hz In H2 0.8% 6Hz In N2 0.8% 6Hz In H2 0.37% 6Hz In N2 0.37% 6Hz In H2 0.8% 0.1Hz In H2 0.8% 6Hz In N2 0.8% 6Hz In H2 0.37% 6Hz In N2 0.37% 6Hz Fig.5 Fatigue crack growth rates h l=1.13 mm dl/dN=2.8×10 -5 m/c l=0.95 mm dl/dN=1.63×10 -7 m/c l=1.06 mm dl/dN=1.48×10 -6 m/c l=1.18 mm dl/dN=1.86×10 -9 m/c l=1.23 mm dl/dN=4.39×10 -8 m/c Crack length l [mm] Number of cycles N 012 3 1 2 3 In H2 0.1Hz In H2 6Hz In N2 6Hz ×104 l Crack length Crack length l [mm] Number of cycles N 012 3 1 2 3 In H2 0.1Hz In H2 6Hz In N2 6Hz In H2 0.1Hz In H2 6Hz In N2 6Hz ×104 l Crack length l Crack length Fig.3 Fatigue crack growth plots (Δεt =0.80 %) Crack length l [mm] Number of cycles N 0123 1 2 3 ×105 l Crack length ( In N2 6Hz ) In H2 6Hz

The microstructure evolution during HPT was investigated as a function of processing parameters: hydrostatic pressure [6], number of revolutions [5], strain rate and temperature for a number of different materials such as Cu [3], Ni [2] and Al [4].
Similarly, homogenisation of microstructure with the number of turns has been observed for copper, nickel, aluminium and Armco iron [1-4].
The predictions of the model with respect to the ultrafine grain size produced by HPT will also be shown to agree with experiment. 2.
The calculated cell size is in good agreement with experimentally observed grain refinement, cf. [3] where the grain sizes of 140 nm in the rim regions was reported.
For hydrostatic pressure of 8 GPa the grain size of 120 nm is predicted which is comparable with the result from [6] reporting a grain size of 100 nm for hydrostatic pressure equal to 10 GPa.

Experimental Material and Procedures The starting material used in this investigation was an extremely coarse grain (grain size ∼ 5 mm) high purity (99.99%) aluminium.
The edge lengths and volumes of the "mean" subgrains and grains Spatial grain intensity NV, surface and grain junction intensities SV, LV.
The structure independent stereological relations are SV = 2NL and LV = 4NA (the mean number of profile vertices per unit area in a random planar tessellation is 6 and any vertex belongs to the three profiles meeting in it, hence the number of profile vertices per profile is 2; the vertices compose together the point processes induced in the section planes by their intercepts with the fibre process of triple grain junction and its intensity is one half of the fibre process length intensity LV).
Lowe (editors): Utrafine Grained Materials II.
Lowe (editors): Ultrafine Grained Materials III.