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At the annealing the atoms diffuse from the specimen's surface into the specimen by two ways, namely, directly into grains and much faster along grain boundaries.
Number 1 denotes component 1, and number 2 - component 2.
This model was used in a number of publications for the description of the Mössbauer data.
This was done in our grain-boundary diffusion model [23,24].
It was shown for a number of systems that the electron density on the Mössbauer nuclei localized in near-boundary areas of a matrix is lower than that in a regular lattice [12,28].

As PWHT temperature increased, a normal grain growth of as-welded equaxied grains ceased and abnormally grown grains with elongated shape coarsened.
Huge elongated grains changed into smaller equaxied grains at 500℃.
As a result, the FSW is now established as a credible method for joining Al alloys. 7055Al-T6 alloys are precipitation hardening Al-Zn-Mg-(Cu) alloys, with a large number of applications in the aerospace and transportation industry. 7055 Al alloy containing Sc (0.1 wt%) have a high strength because the thermal stable dispersoids pin the movement of the dislocation and grain boundary at high temperature, which resulted in the retardation of recrystallization.
The unaffected base metal (BM, a) has the elongated grain structure with high aspect ratio and sub-grain structures are also observed inside the grains.
The smaller particles were still arranged in the grain or sub-grain boundaries and pinned the movement of grain boundaries in the BM.

The number of the acicular ferrite significantly increases in the cast microstructure, and the grains become more fine and uniform.
The number of bainite is largest in the cast microstructure, most of which is distributed at the boundary of the ferrite grains, when the 0.02 wt% CaO is added.
The number of bainite, which is mostly distributed at the boundary of the ferrite grains, increase in the cast microstructure.
The number of the acicular ferrite significantly increases in the cast microstructure, and the grains become more fine and uniform.
The number of the acicular ferrite significantly increases in the cast microstructure, and the grains become more fine and uniform.

The mechanical properties of ultrafine grained Al 6061 alloys were measured by hardness and tensile tests.
The number of rolling passes employed was 22 for the thickness reduction of 88% in the samples.
The microstructure exhibits equiaxed grain morphology with an average grain size of 70μm.
Heavily diffused and ill-defined non-equilibrium grain boundaries are seen in the microstructure.
However, only few grains are observed with clear grain boundaries, within the range of 200 to 600nm.

Extensive grain refinement provided the formation of fully recrystallized structure with an average grain size of ~0.6 μm.
Extensive grain refinement affects mechanical behavior significantly.
In the material with UFG structure at room temperature, a number of dimples with deep conical shape are observed (Fig. 3a’).
First, intergranular brittle fracture takes place occasionally along limited number of planar boundaries of unrecrystallized grains (Fig.4b’).
As a result, a large number of small dimples are observed and crack propagation requires considerable plastic deformation (Fig. 4b’) [12].

Applying electromagnetic field during the solidification of Cu-Fe alloys can further refine grain of hepoperitectic alloys, but has no obvious effect on the grain size of heperperitectic alloys.
The first effect will result in grain refinement via grain multiplication, whereas the second will reduce the number of heterogeneous nucleation sites.
It is believed that in the hepoperitectic region, the grain multiplication has augmented the effect of iron in promoting grain refinement, resulting in further grain refinement, as shown in Fig. 3(b-d).
In the heperperitectic region, however, the grain multiplication has been just balanced by the reduction of the number of heterogeneous nucleation sites, resulting in grain size remaining unchangeable, as shown in Fig. 5(b-d).
(2) Applying electromagnetic field during the solidification of Cu-Fe alloys can further refine grain of hepoperitectic alloys, but has no obvious effect on the grain size of heperperitectic alloys

Grains.
In the sense of this conventional definition of steady-state deformation, the maximum deformation resistance in Fig. 3 is a steady-state (subscript ss) resistance of a material of a given grain structure with a grain size depending on the number of ECAP passes, i.e. on prestrain.
At ambient temperature, i.e. , and 10-3 s-1 the steady-state flow stress increases monotonically with increasing number of ECAP passes towards a constant final value  430 MPa that is reached for (Fig. 3).
While the model is not altogether satisfactory, because it rests on empirical data for the steady-state spacings, it contains a number of observed features of deformation and can be fitted to measured data without losing important microstructural aspects.
Grain coarsening towards the steady state.

Domestic researches are mostly about the effect of grain grading on properties of concrete [6-7].
In conclusion, researches about the effect of different grain grading of sands on properties of mortar is limited.
Thus, according to a large number of water consumption test in the lab and the requirement of construction site, we determined the water consumption of mortar is m(water): m(dry powder)=1: 4.
Fig 1 Influence of grain grading on consistency Fig. 2 Influence of grain grading on strength of mortar of mortar Influence of grain grading on compressive strength and flexural strength of mortar.
Influence of grain grading on bonding strength of mortar.

Some particles, observed at grain boundaries and inside grains, are oxide phases [12].
Effect of the number of ECAP passes on mechanical properties of billets out of Grade 2 Ti.
Grain/subgrain size is reduced to 150-250 nm.
At the next stage of TMT the grain structure with a mean grain size of 100 nm in the cross section is formed with the total accumulated strain of 80% (Fig. 5 a).
The preliminary treatment allowed to reduce the number of ECAP passes, to enhance structure homogeneity and stability of mechanical properties, which, in turn, increased billet quality.

OM and TEM observation showed cryogenic treatment caused by the fibrous grains broken down and many grains with the size of 0.1~3µm These fine equiaxial grains can improve the strength and elongation of the Al-foil.
The grain size of O state with cryogenic treatment is larger than without cryogenic treatment.
From Figure 2(c) and (d), it is evident that there are many small sub-grains with the size less than 0.1mm among the large grains in the O state specimen before deep cryogenic treatment and these sub-grains disappeared and formed large grains with the size of 0.5mm after deep cryogenic treatment which means that deep cryogenic treatment cause the grains merged.
(3) The metallographs show that deep cryogenic treatment cause grains merged with larger size and transmission electron microscope shows that there exist many grains with the size of 0.1~3 mµ after deep cryogenic treatment.
Acknowledgements The authors gratefully acknowledge the financial support from Chongqing Science & Technology Commission (CSTC ) of China granted number 2005BB4108 References [1] F.