Search results

In order to solve the problem of the toughness with high heat input, a number of reasonable solutions have been put forward.
The total number of inclusions is the largest in the Ti-0.032%mass sample but the number is the smallest in the Ti-0.048%mass sample, the value is 3186 and 1835 respectively.
Table 3 Grain size statistics Sample Count Number[mm2] Deq [µm] B1 393 6653 13.8 B2 544 9214 11.8 B3 419 7098 13.4 B4 504 8545 12.2 B5 299 5068 15.9 Fig. 4 Relationship between Inclusion density and grain density In these five samples, the average equivalent diameter reaches the minimum 11.8 µm and the grain density reaches 9214 per square millimeter when Ti content is 0.032%.
The grain growing rate caused by grain boundary curvature can be counteracted by particles’ pinning in grain boundary [6], so the grain can be refined by appropriating inclusions around the grain boundary.
So the main grain equivalent diameter is smallest in B2 sample.

Despite these superior characteristic, quite number of researcher investigate the changes of this alloy after undergone die attach and wirebond process but mainly only focus on the surface area.
Grain size was calculated according to Scherrer’s equation.
The reason is due to larger grain size.
Tensile strength of copper alloy lead frames with smaller grain size is higher than the bigger grain size.
These features were due to larger grain size and lower dislocation density of defect group.

The grain size of surface ultrafine grains was characterized by X-ray diffractometry.
The grain size of surface ultrafine grains on SMATed Fe3Al was characterized by X-ray diffractometry (XRD) on XPERT-PRO diffractometer.
Based on the broadening of (220), (400) and (422) diffraction peaks, calculation showed the grain size of surface grains was about 35 nm.
The above phenomena are all attributed to the lower diffusion activation energy and higher diffusion coefficient which induced by the non-equilibrium defects and grain boundary in nanocrystallines, especially a large number of triple junction boundaries. 4.
Width of deformed layer, grain size of surface grains, phase constituents and microstructure of transition zone in SMATed-Fe3Al/Al and Fe3Al/Al diffusion bonded joint were studied to reveal the influence of ultrafine grains on the weldability of Fe3Al and Al dissimilar materials.

Using stronger ultrafine grained material increased the load and reduced the pin height uniformity.
Micro-billets have lower yield strength for surface grains, different metallurgical orientation of the grains results in less uniform material flow and large surface grains increase friction due to open lubricant pockets at the billet end surfaces.
To overcome some of these problems it is possible to use ultrafine grained (UFG) metals (average grain size less than 1 μm) in preference to coarse grained (CG) metals (grain sizes 10-300 μm) [2].
The findings of the simulations can be used to significantly reduce the numbers of iterations required to successfully produce micro pins in large numbers while improving pin height uniformity.
This obviously occurs earlier for less dense arrays as less material needs to be extruded from the billet into a smaller number of pins.

Experimental results indicate that there are a large number of twin crystals appearing in microstructure of the extruded Mg-Zn-Y alloy sheet at 350 ℃.
The linear intercept grain size is 50 μm.
After annealing at 350 ℃, as shown in Fig.2 (b), a large number of twins come into being throughout the whole grains.
There exists individual grain growth forming large grains and the linear intercept grain size is ～150 μm.
A large number of twins appeared throughout the whole grains after annealing at 350 ℃.

The grain size is controlled by the MCS.
The average grain area is defined as the total lattice site 300×300 divided by the total number of grains.
So the unit of grain area is the number of lattice site.
Then the average grain size is the square of the average grain area.
However, owing to the periodic boundary conditions, the two half grains are actually one entire grain.

The key issue on the use of copper is the formation of copper oxide limiting the number of its functional application.
Few reports figured out that small grain size copper has low oxidation resistance as compared to big grain size copper due to small grain size has larger grain boundaries which has high defect density promoting to higher diffusion rate of atoms [2,5].
Effect of Grain Size.
Once the oxide grains was formed which was smaller than the initial grain of fresh sample, it will create higher formation of grain boundaries.
Napolitano, Measurement of ASTM grain size number, Material Science and Engineering, Iowa State University, available online on http://mse. iastate. edu

Materials A1 and B1 (Fig. 1(a)-(b)) have similar coarse grain size and elongated grain morphology, although, on average, the grains in the latter are coarser than in the former (97 μm vs. 83 μm from linear intercepts).
While material C1 (Fig. 1(c)) contains a number of coarse grains that are sometimes elongated, they are heavily outnumbered by small ones.
Fig. 4 shows a simplistic, schematic depiction of how post-cold-rolling grain sizes vary with the initial (grain) size and shape.
Fig. 4(e)-(g) represents circular grains.
Acknowledgements This research was carried out under the project number MC4.05238 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl), the former Netherlands Institute for Metals Research.

The results showed that grain growth in this Al-4Cu alloy was very limited and grain sizes in the range of 100 nm were still present in the alloys after exposure to 450 °C corresponding to a temperature as high as 0.77 T/Tm.
The grain size of the annealed bulk compacts was measured using TEM analysis.
Also, the bright and dark field TEM images show a large number of nano-sized dispersoid particles.
The grain growth in NC materials is generally suggested to involve grain boundary diffusion [6].
A number of factors, such as grain boundary segregation, solute (impurity) drag and second phase (Zener) drag have been shown to influence the grain boundary mobility in NC materials [7].

The parameter X denotes the number of bridging anions (Si-O-Si, Si-O-Al, Si-N-Si, Si-N-Al) per network forming tetrahedron, for example [SiO4], [AlO4] or [SiO3N].
Table 1: Compositions of the grain boundary phases of all Si3N4 materials after sintering calculated with respect to the mass content of the grain boundaries Compositions of the grain boundary phases calculated from the oxygen distributions in the sintered ceramics [X].
Time / h 0 100 200 300 400 500 Thickness of corroded layer / µm 0 200 400 600 800 KORSiN 4 KORSiN 2 KORSiN 8 KORSiN 9 KORSiN 6 KORSiN 7 a) Number of bridging anions per network tetrahedron / X 1,21,62,02,42,8 Linear rate of corrosion / µm h-1 0 5 10 15 20 25 R 2=0.99 b) Figure 3 a) Corrosion kinetics of Si3N4-ceramics containing different amounts of silica in the grain boundary phase in 1N H2SO4 at 90°C b) Correlation of the initial linear corrosion rates of the corrosion kinetics with the X-Parameter (number of bridging anions per network forming tetrahedron).
In Figure 5b the calculated rate constants are correlated with the X-parameter, denoting also in the glass structures the number of the network forming anions per network forming tetrahedron.
The number of bridging anions per network forming tetrahedron can be rated as an appropriate parameter to correlate the dissolution rates of the Si3N4-ceramics i.e. the grain boundary phases and the YSiAlON-glasses with the structure of the glass-network (Figure 3b and 5b).