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The XRD data in this study were compared with BaTiO3 phase (Joint Committee on Powder Diffraction Standard (JCPDS) data file number 06-0399 [12]) because the Ba(Zr0.05Ti0.95)O3 in this research has only a small amount of Zr.
The porosity decreased with increasing CuO additive content and the microstructure of the ceramics becomes denser (Fig. 4 (b), (c), (d) and (e)) and their grain morphologies are more homogeneous.
The highest density was found in the BZT+2.0 mol% CuO ceramic was 5.76 g/cm3, which corresponds well to the SEM results (Fig. 4 (e)) in which a highly dense grain-packing was observed.
The porosity of surface microstructure of these ceramics decreased with increasing CuO additive content, resulting in denser ceramics and a more homogeneous grain morphologies.
Chan, Effects of grain size on the dielectric properties and tunabilities of sol–gel derived Ba(Zr0.2Ti0.8)O3 ceramics, Solid State Commun., Vol. 131 (2004) 163-168

Nanostructured composite with smaller grains promotes solubility and the finer grade exhibits superior micro fracture strength.
Khan et al. [8] reported the effect of grain refinement on aluminium powder, hardness found to increase due to the grain refinement.
Fang, Dependence of microcrack number density on microstructural parameters during plastic deformation of WC-Co composite, Int J Refract Met Hard Mater. 28 (2010) 434-440
Takacs, Effect of grain refinement on mechanical properties of ball-milled bulk aluminum, Mater.

Table 1 Chemical compositions of low carbon steels used (mass%) Number C Si Mn P S Al Ca 0# 0.004 0.014 0.14 0.008 0.007 0.025 0.002 1# 0.037 0.014 0.14 0.014 0.005 0.031 0.008 Accelerated corrosion test.
Wang et[6] suggested that the dispersion spherical RE oxides and/or oxy-sulfides inclusions in size of <2μm could pinned the grain boundaries which also resulted in fine grain sizes.
Usually the RE inclusions formed in the order as followed[7]: (RE)2O3-(RE)2O2S-(RE)2S3-(RE)S-(RE)N-(RE)C2 (1) Deleterious elements of S and P segregated in the grain boundary were reduced, which could be confirmed with the quantitative results of composition of inclusions, as shown in Table 2 and Fig.2.
RE compound particles might act as heterogeneous nucleation sites and also, hindered the grain growth during solidification process and refined the steel microstructure.

The normal load acted on the diamond grit, which can be obtained by dividing specific normal force component by the product of the length of cutting zone and the number of active grits per unit area [4], was readily calculated.
The calculated normal load acted on the diamond grit for thin blade sawing was from 4.8N/grain to 5.4N/grain, while the corresponding load for normal blade sawing was between 4.7N/grain and 10.5 N/grain, which indicted that little difference between the normal load per grit for the thin and normal blades occurred, and the normal load on the thin blade was far beyond the compressive strength of diamond.

Cast steel of the excavator bucket teeth has a strong initial defect in the form of micropores, shells and cracks, a high level of chemical heterogeneity – segregation main alloying and impurity elements, large unequal primary grains [5].
The authors of many works, including [1,3,4, and others] have analyzed the causes of the tooth destruction and have showed that the center of destruction, in most cases, are casting defects - shells, failures and macro-cracks, contaminated grain boundaries, enriched with impurity elements with low resistance to brittle destruction.
Analysis of studies by a number of authors have shown that the quality of the structure of the material determines its properties, therefore, this factor affects tooth wearing out.
As can be seen from the presented photographs, at the first stage, cracks are developing at the moment of crystallization of castings, and then their movement is carried out in the plane perpendicular to the tooth surface along the grain boundaries.
It has been determined that molybdenum, titanium and other high melting elements, which are introduced into steel to increase cracking resistance hot cracks, which prevent grain growth and the formation of segregations of harmful impurities in the base metal, are in large carbide inclusions incoherent with the matrix and are almost completely absent in the solid solution.

The optimum superheating temperature obtained the fine grains in the alloy is 860℃.
Some researchers [14-15] thought that the increase of supercooling for nucleation would increase nucleating rate resulting in the grain refinment.
When the temperature was high enough, the atom number contained in the atom cluster with the biggest size in Al melt basically tended to a constant, and hardly changed with temperature during the melt superheating on Al melt.
Thus grains again grow up by the action of the interface curvature and interface energy.
Hence, it can be drawn a conclusion that the optimum superheating temperature is 860°C and the suitable isothermal holding time is 25min, in which there are the fine grains in the alloy by melt superheating.

Final recrystallization heat treatment resulted in the formation of a polygonal ferrite grain.
The Fe9wt%Cr alloy has a complex structure with a polygonal type grain and a lath type grain.
The grain size of the investigated specimen was in the range from 10 to 50µm.
The Vickers hardness number of the unirradiated specimen was approximately 100.

The special chemicals cause secondary hydration of cement grains contained in cement paste (these are the grains that have not yet been hydrated).
The thickness of this layer is one of the most discussed issues - some manufacturers indicate unrealistic numbers (without accurate measurement).
There is not possible to measure contact angle value in the place where the grain is.
It is due to the cement paste structure (inhomogeneous material that contains open pores and small grains) because there is always the different cement paste composition for each place of contact angle measurement.

Furthermore, for the micro cyclic deformation features of material, Xie et al. [9] studied the cyclic deformation behaviour of the nanocrystalline Ni and the coarse grain Ni, Zhang and Komvopoulos[10] studied the super elastic behaviour of the Cu-Al-Ni shape memory alloy by the cyclic nano-indentation method.
Finally, the sample surface was corroded electrochemically in the sodium hydroxide solution with a concentration of 20% to get the apparent grain boundary.
In order to decrease the influence of testing errors, each test was repeated three times in the locations far away from the grain boundary.
With the definition of scatter factor as: (1) It is shown that for all the test, the scatter factor are quite small, which means that in the different locations for the same phase far away from the grain boundary, the experimental data scatter is neglectable.
Furthermore, the loading rate is set as 10mN/s, the drift rate is 0.1nm/s, and the cyclic number is set as 30 cycles.

The main reason of plastic deformation included crystal plane slip, twin, grain boundary movement, diffusion creep and so on.
The surface of weld toe will be strengthened, which is mainly manifested in three aspects: firstly, increasing the surface hardness and refining the grain size; secondly, making the surface always in a state of compressive stress; thirdly, decreasing the stess concentration in the weld Table 5 Fatigue test results Treated state Number Specimen thickness/mm Specimen width/mm / MPa Life /Cycle Un-impact 1 2 3 10.16 10.01 10.07 39.80 40.02 40.26 250 0.112×106 0.120×106 0.088×106 Impact 4 5 6 10.02 10.08 10.09 39.92 40.03 39.89 250 0.803×106 0.726×106 0.695×106 Impact and heat treated 7 8 9 10.01 10.03 10.06 40.84 39.98 40.32 250 0.224×106 0.218×106 0.259×106 toe[6].
The aim of heat treatment is to release the residual stress and to maintain the grain size at fine state.
（2）The main reason for improving the fatigue life are increasing the surface hardness and refining the grain size, making the surface always in a state of compressive stress, decreasing the stess concentration in the weld toe.