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These results are described in the present investigation together with a summary of unpublished data on the thermal properties of a number of UHCSs.
The grain size in the coarse grained UHCS was reduced to 7 μm by a subsequent cold rolling and recrystallization process.
The average linear grain size is less than 5 μm.
Thermal expansion tests were pursued at the Lawrence Livermore National Laboratory on a number of UHCS-1.6Al materials containing different amounts of carbon.
A limited number of tests were done on the mechanical properties of UHCS-10Al materials at room temperature.

There are a large number of small particles on the grain surface, the size of small particles is about100nm.
However, the morphology of biomorphic ZnO is not the ideal hexagonal prism, and there are a large number of small particles on the grain surface.
There are a large number of small particles on the grain surface, the size of small particles is about 100nm.

The average grain size increased with decreasing P content.
IF Steel showed polygonal ferrite grain structure.
The grain size distributions measured by EBSD are shown in Fig. 2.
It can been seen that the average grain size increased with decreasing P content The abnormal growth of partial grains resulted in the increase of average grain size.
The average grain size increased with decreasing P content.

With increasing strain (88%) imposed by CR the number of twin bands decreases at the expense of an increasing fragmentation into subgrains (Fig. 3).
The dislocation density in the interior of the grains is low.
With increasing strain (88%) imposed by CR to the UFG material the number of subgrains getting smaller and smaller increases.
Fig. 4 TEM image of Ti processed by 8 ECAP passes; the equiaxed grains are often bounded by high angle grain boundaries.
After 8 ECAP passes (at 450° C) equiaxed grains with sizes from 300 - 800 nm are observed; most of the grain boundaries are high-angle boundaries.

In the region of coarse grained HAZ granular bainite with large grain size can be found as shown in fig.5b, and rod-like and dot-like martensite/austenite constituents distribute on the matrix.
Because of coarse grain size and a number of martensite/austenite constituents, this region always performs local brittle behavior [1].
Weld metal Coarse grained HAZ Fine grained HAZ Hardness(GPa) 3.85 4.11 3.8 Elastic modulus (GPa) 205.8 210.3 201.2 (a) Weld metal (b) Coarse grained HAZ (c) Fine grained HAZ Fig. 3 Typical load-displacement curves of different regions in the welded joint It can be seen that the minimum indentation depth is located in the coarse grained HAZ and the indentation depth between in weld metal and in fine grained HAZ is almost equal value, which indicates that the different hardness behaviors exist in different regions.
According to table 1 the average hardness is as follows: fine grained HAZ＜weld metal＜coarse grained HAZ.
It can be seen that the average value of E is 205.8 GPa, 210.3 GPa and 201.2 GPa in the weld metal, coarse grained HAZ and fine grained HAZ respectively.

The simulation of a representative microstructure starts by populating these cells with pre-specified numbers of nuclei.
(a) The structure domain divided into a number of finite elements; one element is shown with its expected array of cells.
At this stage of the 2D model formulation, these are numbers that reduce to angles of 0°, 30°, 45°and 90° with the principal straining direction.
Fig. 10 shows the grain structure in element number 3 located at the bottom-left hand corner of the specimen (third from bottom of element set A (shaded)).
Effect of grain size Fig. 12 displays the stress predictions for a change in the initial grain sizes, one with large grains and the other with small grains.

The final microstructure is then related to the number of nucleation sites available at the onset of solidification and the subsequent solid/liquid conditions that control grain/dendrite coarsening.
These fragmented dendrite arms then act as embryonic grains to promote a grain multiplication effect, resulting in a refined, equiaxed microstructure.
For example, a grain size of a few micrometers can be achieved for a spray formed Al alloy billet as large as 300mm in diameter.
Phase field modeling indicated that the eight seed crystals fully developed into dendrite grains with many secondary arms and tertiary arms as showed in Figure 2 (c) during the initial solidification.
After an instant thermal shock of 1330 °C for 0.28 s, the majority of the secondary arms including some tertiary arms were remelted at their roots, and detached from the main trunk (Figure 2(d)), increasing the discrete solid particle number to ~70.

Nonetheless, a number of negative consequences tend to be possible [2].
While flame heating until 3550C, it was observed that the morphology of the grains retained austenite as evident in Figure 2a, and thus, changes not from the initial grain structure.
In the Figure (1a), shows the Micrograph of initial grain structure and average hardness plots (1b) of the same grain structure at room temperature as HRC 29.
(Slightly higher than those obtained on the initial grain structure).
Figure 4 shows average hardness as HRC 24, 29 29.3 as results; on surface grain structure after flame heated to 550⁰C, on surface of initial grain structure before flame heating and on grains beneath the surface of flame heated samples to 550⁰C respectively.

To produce a range of different structural states the initial coarse-grained samples were subjected to HTP with the following number of rotations of the mobile anvil n=0, 0.25, 0.5, 0.75, 1, 1.5, 3, 5, 7, 10.
Dependence of long-range order parameter (a), internal strains (b), size of the domains of coherent scattering (c) and microhardness (d) of Ni3Al on the number of mobile anvil rotations n.
As strain increases, three systems of shear bands form, their number increases but the width decreases.
Deformation of such materials is realised by a large number of small micro-shears along grain boundaries.
Thus, shear deformation by grain-boundary sliding and micro-shearing along grain boundaries becomes difficult.

The structure of ZnO can be described as a number of alternating planes composed of tetrahedral coordinated O-2 and Zn+2 ions, stacked alternately along the c-axis.
Their sintered disks form grains with narrow size and narrow size distribution, pure grain boundaries and inherent stability against grain growth [16].
The dimension of ZnO grains was (0.5-2.26) µm and (80-119) nm for sample A and sample B respectively.
So upon pressing and sintering the compactness of the grains increases while the number of pores and voids decrease relative to sample A [16].
Since c1 is a measure to the temperature T (K) which the filaments can reach, then it is proportional to the grain dimensions, i.e. large grains with imperfections, defects and voids are heated more.