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(4) where R is dendrite tip radius, Γ is Gibbs-Thomson coefficient, Pei is Peclet number, mi is liquid slope,C0,i is initial concentration, ki is partition coefficient, ζc(Pei) is function of Peclet number, Iv(Pei) is Ivantsov solution (where subscript i=Cr or Al), Ghkl is temperature gradient along the crystallographic orientation.
Three typical weld defects, severe stray grain formation, centerline grain boundary formation and asymmetrical solidification cracking, are simultaneously mitigated to improve weld quality.
Stray grain formation in welds of Ni-based superalloy CMSX-4.
Stray grain formation in single crystal Ni-based superalloy welds.
Analysis of stray grain formation in single-crystal nickel-based superalloy welds.

A special etching (CuSO4 + HCl) was also used to distinguish the grain structure.
The grain refining tests were performed on only one cutting temperature (590°C).
This is because a large number of nuclei are generated at low pouring temperatures, while at higher pouring temperatures it is impossible to produce a number of nuclei and the nucleation takes place during the first stage of the SEED process [6-7].
It seems that at higher pouring temperatures the addition of TiB2 does refine grain size, but this grain refining is not translated into a noticeable reduction of the α-Al particle size.
• The addition of TiB2 indeed reduces the grain size at all pouring temperatures.

Microstructure evolution and tensile properties were studied in a bainitic pipeline steel grade by performing a number of physical simulations on samples machined out of an industrially produced transfer bar.
During the rough rolling the austenite grain size is refined due to repeated cycles of work hardening and the recrystallization process.
The austenite status at this stage - regarding the prior austenite grain size (PAGS) and precipitation - simulates the condition of austenite after the roughing process.
On the other hand, a value of 60 s for tV was enough to attain the saturation point for large prior austenite grains deformed at high temperature (Fig. 5b and 5e).
Summary Microstructure evolution and tensile properties were studied in a pipeline steel grade API-X80 by performing a number of physical simulations on samples machined out of an industrially produced transfer bar.

Rotation of grains leads to emergence of high local internal stresses.
Rotation of grains leads to emergence of high local internal stresses (fig.3).
So, high chemical activity of gallium turns this technological task into a sufficiently complicated process which depends on the number of both positive and negative factors.
Mass transfer of gallium into Al alloy between grain (SEM).
The diffusion results in an intense growth of grains sizes and volume of the detail, in shifting of old grain boundaries and formation of new ones.

Spherical grains can be obtained by several semisolid processes in aluminium alloys.
As the dislocation density increases, there will be more grains for recrystallisation.
Thus, grain structure will be more refined [2].
Spherical grains of 7075 (a) treated at 575oC for 35 min (b) treated at 600oC for 20 min Fig 2 shows the SEM image of the spherical grains of 2024.
Comparison of the elongation at fracture results for 2024 and 7075 alloys Fatigue tests were applied after PH process to several numbers test bars in both quenching mediums (Quenching in RT Water / RTW-Q and Quenching in Boiling Water [80°C] / BW-Q after SHT).

Most of these effects are related to the nanometer-scaled grain size.
Carbon will pin dislocations and grain boundaries, slowing down the dynamic recovery process.
This is in contrast to the ductility which is limited by the number of inclusions.
The number of inclusions and the purity content are correlated.
An increasing amount of impurities leads to a higher number of non-metallic inclusions, restricting the intrinsic ductility.

With nitrogen rate (168 kg/hm2), irrigation (90 mm) in jointing stage, and irrigation (70 mm) in heading stage, grain yield was higher.
Five factors were showed by capital letter (A, B, C, D and E) and four levels were showed by number in right hand of capital letter respectively.
It also showed that irrigation was main factor of improving and ensuring crop grain yield in arid region.
Therefore, the optimum combination of higher GY grain yield was A2C1D2.
Grain water use efficiency (GWUE) comprehensively reflected the relationship between water consumption and grain yield.

A small number of laser shots and a low temperature of substrates (series 1) probably slowed or stopped the processes of diffusion and coalescence of the already grown grains, which caused the situation that substrates were not uniformly covered with BN.
Registered grains have similar, small sizes (Fig. 1).
The morphology and phase maps of boron nitride coatings An increase in the number of laser shots, the energy of laser and the power of the RF discharge generator (series 4) cause that the substrate is completely coated by boron nitride; moreover, a larger variety of the size and shape of grains can be observed, as a number of quite large grains with an elongated shape have appeared.
On the surface of large grains and among them, a significant amount of small grains can be observed.
Such variation in conditions resulted in the noticeable growth of the grain size.

The strength of Cu-Ag alloys is determined by a number of strengthening mechanisms, which to a certain extend influence each other.
Work hardening originates from the cold work, that is applied in order to prepare the wire in its final dimension, and thus takes into account both, the increasing number of dislocations and the decreasing grain size.
Perpendicular to the drawing direction, i.e. the shorter length scale of the grains, a mean grain size in the order of 100 nm is estimated by TEM analyses.
From Fig. 5b primary recrystallised grains can be seen, which have a mean grain size right below 100 nm.
However even coarsened grains are observed after annealing the sample at this temperature.

Deformation at all test conditions leads to modification of the coarse-grained lamellar microstructure to fine-grained one.
The recrystallized grain size is less than the thickness of the initial α-plates.
Firstly, the rise of hydrogen concentration in the alloy can lead to an increase of the number of recrystallization nucleating centers.
Secondly, the hydrogen addition reduces α-grain growth as confirmed by measurements of grain size after annealing at 650°C in air (Fig.6).
Hydrogen influence on α-grain growth in CP titanium during annealing.