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The early researches have proved that low Fe, Si impurity content and relatively fine grains can effectively enhance fatigue crack propagation resistance [7,8].
Table 1 Chemical composition of two Al-Zn-Mg-Cu alloys Alloy number Zn Mg Cu Zr Fe Si Al 8.0Zn+1.8Mg alloy 8.0 1.8 2.0 0.1 <0.1 <0.1 Bal. 9.0Zn+2.0Mg alloy 9.0 2.0 2.0 0.1 <0.1 <0.1 Bal.
And the larger cycle number is, the more obvious difference of crack length between the two alloys.
Effect of grain size on fatigue-crack growth in 2524 aluminium alloy, Int.
Influence of precipitates on low-cycle fatigue and crack growth behavior in an ultrafine-grained aluminum alloy, Acta Mater. 2014, 80: 250-263

The addition of small amounts of Mg to a galvanizing bath caused a Znhcp/MgZn2 eutectic to grow at the grain boundaries.
The addition of small amounts of Mg to a galvanizing bath caused a binary Zn-hcp/MgZn2 eutectic to grow at the grain boundaries and at some places at the coating surface (Fig. 3).
With 0.1wt% and 0.2wt%Mg added, the cracks were mainly along the grain boundaries, with higher Mg additions long cracks in the direction of the bending axis were present (Fig. 7).
(a) 0wt%Mg, (b) 0.1wt%Mg, (c) 0.2wt%Mg. 0 2 4 6 8 10 12 10% rust 1% rust 0.5% rust 0.05% rust no rust 0%Mg 0.1%Mg 0.2%Mg 0.5%Mg 1%Mg number of weeks 10% 1% 25% 40% Number of cycles Summary A thermodynamic model for the Zn-rich corner of the Zn-Al-Mg system was developed.

The metallographic observations of additive manufactured samples showed a martensitic microstructure inside the prior β grain grew up as columnar structure.
One more advantage of the additive technologies could be the possibility to reuse the part of powder that has not been used in the forming process, but, as the number of recycles increases, their properties are expected to change.
The sample Ti6Al4V, used as a benchmark, consisted of equiaxial α-phase grains distributed in the β phase matrix (Fig. 1.1).
Whereas, the DMLS samples (Fig. 1.2 and 1.3) in the building direction presented a columnar grains structure with elongated prior β grains, in which a martensitic structure was found.

Physico-mechanical properties of abrasive materials Name abrasive materials (in grain)* The properties Density g/cm3 Micro hardness, MPa Mineralogical Hardness scale, conventional units Grain Strength, Н Synthetic electrocorundum “α”Al2O3 3.97 19025-24600 9.0 8.8-10.7 Carborundum - silicon carbide SiC. 3.21 25000-30000 9.0 11.0-14.7 Carbide bora В4С 2.52 48500 9.3 36.0-38.0 *Fraction of abrasive materials 1.8 - 2.0mm.
In the delivery state, all materials have a spiky grain shape.
Due to the high hardness and strength of the grains of boron carbide abrasive, it can be used repeatedly for pneumatic surface preparation.
Material 1st layer Material coverings 2nd layer Material coverings 3nd layer Weight gain samples, mg Heat resistance, ∆g′τ , mg/cm2 spraying area cm2 1 Heat resistant alloy sample Number 5 Cobalt based alloy Cobalt Alloy + aluminum and chromium oxide spinel Spinel based on aluminum and chromium oxides 41.8 0.77 14.6 0.27 54.1 5.0 0.08 2 Heat resistant alloy sample Number 6 Nickel aluminum alloy Nickel-aluminum alloy + spinel based on aluminum and chromium oxides Spinel based on aluminum and chromium oxides 44.1 0.81 15.2 0.28 54.1 5.2 0.09 3 Heat resistant alloy sample Number 7 Cobalt based alloy Cobalt Alloy +zirconium dioxide + nickel Zirconium dioxide + Nickel + Heat Treatment 131.8 2.43 32.0 7.6 54.1 16.6 0.3 4 Heat resistant alloy sample Number 8 Nickel aluminum alloy nickel-aluminum alloy + zirconium dioxide + nickel Zirconium dioxide + Nickel + No Heat Treatment 249.8 4.6 66.2 1.2 54.1 33.1 0.6 5 Heat resistant alloy sample Number 9 Composite chrome aluminum Composite chrome-aluminum
+ spinel based on aluminum and chromium oxides Spinel based on aluminum and chromium oxides 20.5 0.38 7.2 0.13 54.1 2.4 0.04 6 Heat resistant alloy sample Number 10 Nichrome X20H80 Nichrome X20H80 + spinel based on aluminum and chromium oxides Spinel based on aluminum and chromium oxides 30.2 0.56 9.1 0.17 54.1 4.8 0.09 *Heat resistance after 3 heating cycles for 5 hours at 1000ºС An analysis of tabular data (Table 3 and Table 4) shows that an increase in the heating time of samples from 5 to 15 hours leads to an increase in the heat resistance of coatings, i.e. the use of protective 3-layer coatings improves the resistance of the base material.

The grain size entering F1 is not appreciably different from that entering the furnace [1,4].
Typically, these are subgrain or grain boundaries in the austenite.
This diagram will change with starting grain size, composition and interpass time.
It is based on achieving both grain refinement and pancaking of the austenite grains, all within the six pass finishing train.
As the pass strain increases, more of the poorly oriented grains will show a sufficiently high enough dislocation density that they will exhibit nucleation and recrystallization, grain refinement and subsequent uniform final microstructure. 0.06C-1.5Mn-0.35Si-0.04V-0.025Nb-0.025Ti-0.0045B0.0075N, Final Thickness: 3.25 mm 0 10 20 30 40 50 F1 1092 F2 992 F3 966 F4 939 F5 914 F6 892 Finishing Pass Number and Entry Temperature, °C Relative Units Material Flow Stress Roll Force Rolling Torque Fig. 7 T - ε pass sequence data Kozasu, et al., studied the recrystallization of coarse grained austenite in the early 1970s [12] and showed that recrystallization of coarse grained austenite can occur only with very large reductions, of the magnitude found when stands F3 and F4 are dummied (as shown in Figure 7).

Our research investigates the correlations between domain textures and microstructural features, including crystallographic textures in bulk and thin film polycrystalline materials to understand the development of piezoelectric and other anisotropic properties in a number of rapidly evolving lead free piezoelectric materials.
Crystallographic texture has been induced in lead-free Bi0.5Na0.5TiO3 (BNT) using templated grain growth.
BZT-50BCT samples have a random grain distribution, MRDcrystal=1, resulting in the total MRD of the 002 pole equaling the ferroelastic texture of the 002 pole, MRD002.
The preferred growth direction in templated BNT is along a non-ferroelastic rhombohedral h00 peak, MRDferro=1, therefore the total MRD equals the preferred orientation induced by template grain growth.

Some structures have, or approach having, property gradients that are continuous' at a size scale that is of the order of a few particle or grain sizes.
Recently, solidified fine-grained TiC-TiB2 composite is achieved by combustion synthesis in high-gravity field [4, 5].
FESEM fractograph of the ceramic matrix showed that fracture mode of the ceramic coating presented one mixed mode of intergranular fracture along TiB2 platelets with transgranular fracture in TiC grains, as shown in Fig. 2, and a number of fine TiB2 platelets as the primary phases participated in crack bridging and subsequent pull-out process during crack propagation, thereby making a major contribution to toughening ceramic.
FESEM image of fracture morphology showed that a mixed fracture mode was presented that intergranular fracture and transgranular fracture happened either along or in the solidified column-like α’-Ti grains nearby the joint, as shown in Fig. 7.
Because of the presence of the molten Ti alloy, the formation of the column-like α’-Ti grains is considered a result of rapid solidification followed by martensitic transformation β→α’ of Ti alloy, and shrinkage cavities have to reside in the boundaries of the column-like grains or between the solidified Ti alloy and joint, as shown in Fig. 6, Hence, the solidified microstructure in HAZ of Ti alloy becomes the the poor part in the joint, thereby presenting fracture strength smaller than either the solidified ceramic or the joint area, finally, and shear fracture usually occurs either along or in column-like grains of α’-Ti.

The average cluster size is found to be dependent on the number of the sintering time.
The experiment analysis shows that the grain size decreases with repeating grinding sintering.
Curve (c) in Fig. 1 shows COOH- bond characteristics between wave number 3250 – 3550 cm-1 however the same is absent in curve (b) and (c).
The DC CVC bears the signature of different nano cluster with probable variation of grain size.

A large number of experimental studies believe that alloying elements such as Al, V, Mn, Cr, Mo, B, and C can improve the plasticity of the alloy.
A large number of secondary cracks can be seen at the fracture.
It can be seen from the picture that the secondary cracks extend along the grain boundary, and the cracks propagating along the grain boundary will eventually form a rock sugar block-like fracture morphology.
A large number of secondary cracks can be seen at the fracture.
A large number of secondary cracks can be seen at the fracture.

A number of Cr precipitates and Cr-rich clusters were observed after the ageing treatment with direct current.
Moreover, the direct current prevents the precipitation reaction, and the retarding effect is related to the sweeping out of quenched-in excess vacancies in to grain boundaries by electromigration.
A number of Cr precipitates (A) and Cr-rich clusters (B) appear in Fig. 2(b).
Bright-field TEM micrographs of the sample aged at 400 °C for 1 h: (a) without current, (b) with 70 A/cm2 Zhou et al. [9] reported that electropulsing can increase the nucleation rate on the early stage of recrystallization and retard the subsequent rate of grain growth.