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The coarse-grained alumina specimen, TM7, was selected for additional testing, in the hope of analysing the effect of incident wave shaper with regards to strength results.
Influence of grain size on the dynamic response behavior of alumina.
SHPB stress-strain curves for alumina ceramics with different grain sizes It is well known that microstructural inhomogeneities caused during material preparation (e.g. inclusions, grain boundary impurities, secondary phases, porosity, etc.) are the main cause of cracking and can lead to material fracture.
As the applied load increases rapidly, the inertial effect of accelerated crack expansion prevents the initial stage of material fracture from occurring, and microcracks are generated in large numbers but do not converge, the material remains integral at this point and therefore ceramic materials exhibit a high compression strength under high strain loading.
The fine grain alumina ceramic SH3 exhibited a high dynamic compressive strength of 3.80±0.25 GPa, as compared to the SHPB experiments conducted on the alumina ceramic materials.

Introduction The properties of nanograined intermetallics strongly depend on the grain size, the morphology of grains, the homogeneity of grain size distribution, the relative crystallographic orientations and the nature of grain boundaries [1,2].
Results Fig. 1 shows the variation of microhardness, HV0.2, against shear strain (γ) after processing by HPT for four different numbers of turns at (a) 473 K and (b) 573 K.
Fig. 2 shows XRD profiles for the samples processed at (a) 473 K and (b) 573 K after different numbers of turns including the initial powder mixtures.
The fraction of the Al3Ni intermetallic increases with increasing number of turns, i.e., increasing shear strain.
In addition, a peak broadening occurred as the number of revolutions increased, indicating the introduction of lattice strains, dislocation generation and grain fragmentation during the HPT processing [5,6].

As a result we get a large number of tiny grains.
Because the grain boundary atoms are arranged in disorder, and there are a large number of defects such as dislocations, empty.
Besides on both sides of the grain size of a grain boundary to different, so it will hinder dislocation from one grain to another grain movement.
The number of toughening nest became fewer, and its morphology is smaller.
Toughening nest increase in the number with smaller in size, uniform in morphology, no particles.

These results show microstructure one of the sample for sample number 3 which exceed the highest average overall length A that become more globular with higher average grain size after the feedstock billets were re-heated to semisolid range temperature.
Table 3 shows average grain size measurements for microstructure of sample number 3 consists of area, perimeter, circularity, diameter and aspect ratio.
Table 3: Average grain size measurements for microstructure of sample number 3 before and after injection test.
At this time, grain spheroidization and coarsening were started when liquid phase at grains boundaries.
As the initial microstructure of feedstock billets in sample number 3 were surrounded by higher secondary phase content, it catalysed the formation of smaller α–Al solid grains.

Abstract.Within the general context of solid-state sintering process, this work presents a numerical modelling approach, at the grain scale, of ceramic grain packing consolidation.
This grain boundary surface tension condition can be written as follows: [σn]gb = γgbκn (21) over the grain boundary Γgb, and has to be added to the mechanical problem (12)-(14).
One of the difficulty of simulating grain boundary diffusion is that we have to consider one level-set function per grain.
As in [6], the simulations presented in this work have been performed by using a mesh adaptation strategy aiming to obtain accurate results while keeping a ``reasonable'' number of mesh elements.
The mesh adaptation strategy used allows to perform simulations while keeping a ``reasonable'' number of nodes and elements and is specially useful when dealing with 3D simulations as the number of mesh element is dramatically increased compared with a 2D simulation.

Finally, the hardness values are reasonably homogenous along the disc diameter as the number of turns increases to 5 and 10 turns.
There are some reports on the grain refinement during HPT processing of Al-5% Mg [9] and Al-1% Mg [10].
The grain structures in the HPT-processed Al-0.1% Mg were also examined by EBSD using a JSM6500F SEM.
Fig. 3(a) shows the disc centre area has coarse grain structures but with higher number fractions of low-angle boundaries introduced by HPT shear deformation.
Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog.

Relevant data are available in a relatively large number on Al-Mg-Sc/Zr alloys with a Mg content ranging from 1 up to 6 mass % [8-12].
By increasing the number of passes, the sub-boundary misalignment increased, as confirmed by the increased spreading of the spots of the SAD patterns.
Grain structure of the materials investigated after 4 ECAP passes.
This effect is confirmed here by the shift of the above mentioned peaks toward lower temperatures by increasing the number of ECAP passes of the samples
Ultrafine grained materials.

The increase of the reaction temperature will decrease the number of the crystal nucleus.
The specific surface area and grain size of these powders are shown in Fig. 4.
The grain size increases with the increase of the concentration of TiOSO4.
The existence of [H +] will hinder the process of nucleation, so the increase of concentration of [H +] will decreases the number of the crystal nucleus.
The grant number is 50472094.

The number of active substrates in the domain of the melt with the undercooling ∆T below the liquidus may be calculated on the base of cumulative distribution function F(∆T) [31].
Mean number of active substrates in one cell: ( )STFNN max ∆= . (10) where: Nmax is the maximum specific number of the substrate for nucleation, S is the area of cell.
All graphite grains in this figures are black.
Every austenite grain has its constant gray level.
It was shown, that each austenite grain can coverage several graphite nodules.

Truncation error analysis.For the accuracy of the solution, a minimum number of base functions is necessary.
This analysis proved that the drying rate increases with increasing number of pauses.
b) Application to drying of rice grains with husk.
In addition, the drying rate increases with increasing number of pauses.A diffusion model was proposed to describe continuous and intermittent drying of rice grains with husk.
[2] M.J.Milman,Equipments for pre-processing of grain.