Search results

The processing parameters are laser power 650W, scanning speed 240 mm/min, powder feeding rate 2.5 g/min, laminated depth 0.2 mm, accumulated layer number 6 layers.
It can be seen in Fig. 3 that the grain structure of as-deposited clad is refined and uniform, and the mean size of grains is about 10 μm.
The cellular grains and the dendrites can be observed in Fig. 4, and the refined cellular grains account for the majority.
When the grains whose crystallographic axes obliquely intersect the interface grow to some extent, they would encounter the adjacent grains and stop the continuous growth.
When this size reaches a certain value, the cladding microstructure begins the morphology transformation from dendritic grain to cellular grain.

Paul: Materials Science Forum Vols. 500-501 (2005), p. 677 However, these studies involve a large number of variables such as steel composition, initial grain size, and deformation condition (temperature, amount of strain, strain rate and type of deformation).
A Vol. 499A (2009), p. 7 which is capable of calculating flow stress as a function of strain, strain rate and temperature as well as alloy composition and grain size.
A link between flow stress and the number of potential nucleation sites.
For the case where site saturation occurs, one has: (2) where N0 is the total number of active nucleant sites per unit volume, i.e. the saturation number density.
Rainforth et al. studied the precipitation of NbC in an Fe-30Ni-0.1C-0.1Nb-1.61Mn (wt.%) steel of initial grain size 370 mm.[] W.M.

In which way do grain boundaries influence the reaction?
In these plots, the size of the nucleus is expressed by N, the number of atoms contained.
Diffusion in nanocrystalline thin films With decreasing grain size, grain boundaries will contribute considerably to the total volume of a thin film.
In nanocrystalline matter with grain sizes of about 10 nm, the volume fraction attributed to grain boundaries (GB) can easily exceed 50%.
Ni diffuses into the grain boundaries of Cu, and Cu into the grain boundaries of Py vice versa.

The ingot structures changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm and to the granular with a mean grain size of about 50µm at higher than100 rpm.
Once a rotation process was given, the dendrite structure changed to a rosette-like one at the rotational speed of 50rpm (Fig.2(b)).At the speeds higher than 100rpm, the structures became almost equiaxed and had a similar mean grain size of 50µm, as can be seen from Fig.2(c) - (f).
Therefore, it was concluded that the most favorable condition of rotational speeds for making the sound slurries were 100 and 150rpm because of no clear differences in sizes and morphologies of grain structures in the every specimens treated by the rotor process with rotational speeds of higher than 100rpm.
The melt flow due to rotations of the rotor uniformly generates enormous numbers of solidification nuclei at the surfaces of both the chill block and the rotor.
At the same time, the slurry containing numerous numbers of small crystals was continuously discharged from the outlet of the gap.

Microhardness test of Joint Hardness number of joints is considered as an extraordinarily important indicator to judge quality of joints in researching mechanical property of welding joints because hardness number directly determines anti-deformation and anti-destruction capacity of the joints.
Hardness number and hardness changing interval of all regions could be obtained to judge quality of joints and speculate tissue ingredients of all regions through testing on region of welding nugget, region of heat influence, region of basic materials and other regions.
The changes above of microhardness are based on structure which sequence from center of the nugget to base metal: Coarse lath M—Coarse M—Fine M+Small quantity of F—M+F—M or M+Minute quantity of F, microhardness number increase as more M exits.
Microhardness number increase in overheated zone and fine grained region for the martensite of this region is thinner than nugget zone.
(2) Basic metal structure of hot-stamped steel is small, hard and compact lath martensite. structure of heat-affected zone is small martensite structure and the structure gradually move from region of refined grain to region of rough grain because cool-down speed of joints are slowed down from basic medal to region of nugget.

In order to increase the number of diffracting grains for the small gauge volume, it was shifted by 20 mm in longitudinal (x) direction during the measurement of longitudinal strains.
Both material versions tested had pancake-shaped grains; for example, the HDT-version contained grains of average length of about 108 µm and width of about 23 µm which gives an aspect ratio of about 4.7.
The grain size proved to be small enough to ensure a good grain statistics even with the small gauge volume.
The sheet was rotated from -2.5° to 2.5° around an axis perpendicular to the weld line during data acquisition to increase the number of diffracting grains.
As the number of diffracting grains was still small, a 60° wide sector was used for the calculation of the transverse strain.

The median grain diameter (Md) ranges from 0.072mm to 0.275mm while the content of carbonate content ranges from 5% to 14.8%.The average content of shale is 6.625 %.
The degree of sorting and roundness for grains varied from medium to poor and the anisomerous texture could be shown.
Table 1 Petrologic characteristic for Well Zaojian1 in Zao IV Group layers number percent（%） naming cement weather degree sorting degree roundness Cement type Q F R IV1-2 33 39 28 fine-grain mixed Sandstone mica clay, calcic medium- light good subrounded Pore- cement IV2-1 33.3 41 25.67 medium- grained mixed sandstone clay, calcic medium- light Good- medium hypocone- subrounded Pore- cement IV2-2 32.15 40.31 27.54 fine-medium grained mixed sandstone clay, calcic medium- depth Good- mediu hypocone- subrounded contact cement Pore structure characteristics The main pore developed in sandstones reservoir is intergranular porosity, there are also few moldic porosity and component within the pore.
Zao 62-24 wells total samples taken 18 copies, numbered 46-50, 52-64, 2 parts are good, 13 are medium, and 3 are poor.
Table 2 Pore structure characteristics of Well Zao 62-24 number 49 54 56 59 62 depth（m） 2000.85-2000.95 2015.40-2015.50 2022.67-2022.80 2036.18-2036.28 2037.40-2037.50 physical features K（10-3μm2） 60.40 241.00 599.00 26.32 1091.00 φ（%） 21.65 25.74 22.91 23.05 22.94 throat features Pd（MPa） 0.1385 0.0764 0.1940 0.1814 0.1798 Rp(μm) 5.8406 3.6992 4.6264 3.7449 4.6170 Sma×(%) 63.6295 47.1881 64.1285 50.2049 62.4270 SP 16.3226 11.6842 15.6989 27.3520 17.0020 R50(μm) 0.2871 0.0000 0.2708 0.0258 0.1285 pore structure level medium bad good medium medium Physical characteristic By using the analysis data of core laboratory for well Zao Jian 1, it was showed that the minimum porosity of Well Zao 1 in Zao IV Group is 18.23% while the maximum of it is 26.50%.Generally concentrated in20%-28% with an average of 23.81%.

The resultant weakly agglomerate and spherical particles have a uniform grain size about 20nm after calcined at 850°C for 2 hours. 3mol% Eu 3+ doped Y2O3 nanopowder shows an intense red luminescence at 612nm under UV excitation.
Wave number/cm-1 10 20 30 40 50 60 70 0 Intensity/a.u. 2Theta/o Fig.2 IR spectrum of the dried Y2O3:Eu3+ precipitate precursor.
Lower calcining temperature could not decompose the precursor completely, and higher temperature would result in grain growth and sintering of adjacent particles, which is disadvantageous to the luminescence properties of Y2O3:Eu3+ nanopowder [4].
It is known that the luminescence of a given phosphor depends mainly on its shape, size, crystallinity, defects and grain boundaries [4, 6].
Microstructure investigations using SEM and TEM show that the as-prepared weakly agglomerate nanopowder has a relatively narrow particle size distribution; the average grain size is around 20nm in diameter.

A number of semi-solid casting researchers have reported that using semi-solid casting helps to reduce the hot tearing and improve the strength of Al-Cu alloys.
The convection is conveyed until the melt becomes slurry, with the solid phase consisting of many fine grains in near-globular or non-dendritic shape.
A coarse dendritic structure with grains of α phase was observed in the normal gravity casting samples, as illustrated in Fig.5(a).
In addition, the grain size of all semi-solid gravity cast samples is smaller than that of conventional gravity cast samples, as shown in Fig. 6.
Fig. 6 Average grain sizes of the α-phase in A201 in conventional and semi-solid castings.

It is evident that the annealing temperature, which leads to the remarkable improvement of films crystallization, changes both the grain size and the grain shape remarkably.
Annealing can promote crystalline growth, which contributes to the activation of the dopant and reduces the number of donor sites trapped at the dislocations and grain boundaries and increases the carrier concentration.
Zr-doped film deposited at room temperature showed the enhancement in (400) orientation and the increase in grain size.
With an increase in annealing temperature, the intensity of XRD peak increased and the grain size showed an evident increasing.
ITZO films had better crystalline structure, larger grain size and lower surface roughness than ITO films after annealing.