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Ultra-Fine Grained Al-SiC Metal Matrix Composite by Rotary Swaging Process S.
From Fig. 1(b) and 1(c) one can see that the microstructure is becoming more uniform as the number of passes increases.
These are interpreted as steps created on the grain boundary (surface) by the movement of a number of dislocations in the same slip plane.
In each stress cycle it is very probable that a large number of dislocation move across the grain from boundary on the same slip plane leading to a displacement in multiples of burgers vectors of the dislocation.
The spacing between the dislocations being less than 100nm indicates that it is a high angle twist boundary created as a result of relative rotation between grains which could have been a single grain with a low angle sub-grain boundary created in the initial stages.

Introduction The fine-grained structure (typically ≤ 10µm) is in general known to be an important factor for a number of superplastic alloys.
In the condition of coarse grained material (16.2 µm), a number of dislocations are observed both near the phase/grain boundaries and inside the α grains, which indicates a transition from boundary sliding to matrix deformation and deformation occurs in β phase as well as α phase with the coarsening of grains.
Many researchers [5-9] have studied the grain growth in fine grained materials (≤10 µm) during SPD.
And the grain growth model during superplastic deformation has been utilized to analyze the grain growth.
(2) For coarse grained material (16.2 µm), dislocations are not only observed in the vicinity of the phase boundaries but also inside α grains and near the α/α grain boundaries, and subgrain boundaries are observed in α grains.

Simulation of Grain Growth Under the Effect of Stress F.
Through grain boundary engineering [1], certain populations of grain boundaries are enhanced thus a grain boundary character distribution is favored [2].
Recent three dimensional grain growth simulation with anisotropic grain boundary energy was successful in replicating the experimental observations of grain boundary character distribution [6].
It is clear that stress changes the evolution of the grain boundary network during grain growth.
Use of facilities provided by the MRSEC at CMU under NSF grant number is DMR0520425 is also gratefully acknowledged.

Mechanical Properties of Ultra-Fine Grained Al-Li Alloys B.
During 8 passes of ECAE process, coarse grain microstructure in the initial state transforms into ultrafine grained.
In these pictures, deformed and highly elongated grains are visible.
As the number of passes increases from 4 to 8, a development of grain-like structure (Fig. 3b) and a slight refinement of the grain size are observed.
In this term, the grain elongation factor α, defined as a ratio of the maximum diameter of the grain to its equivalent diameter was analyzed.

It is important to state that the aim is not to completely replace experiments but reduce their number and improve their efficiency by predefining which samples are better suited for experimental validation.
Additional features such as number of neighbors, triple junction angles or clustering of some properties might be considered as well, but are ignored for the time being.
If n points are randomly placed in a box of which the size depends on the number of grains n and the average grain size of the target distribution, the resultant distribution is the so-called Poisson-Voronoi which exhibits a lognormal distribution with a variance of 0.424 [2].
(c) 3D section of the resultant grain set.
Once the grain set is defined, the following step is to create the texture by assigning orientations to each grain.

The distribution of crack number per specimen with 4 notches for crack depth is shown in Fig.2.
The GBCD control decreased the maximum crack depth in C-doped steels, while the GBCD control decreased the number of IGSCC in C-free steels.
Therefore, IGSCC propagates along higher energy grain boundaries.
An EPR test revealed that the reactivation ratio of C-doped and C-free steels were 34% and <1%, Grain boundary character; Fig.1 OIM maps of cross section around IGSCC in a GBCD controlled C-doped steel. 200µm (a)SEM image (b)IQ map (ｃ)GBCD map Notch bottom Notch bottom Notch bottom IGSCC Lower IQ-value zone Random Σ1-29 Grain boundary character 0 1 2 3 4 5 0 1 2 3 4 5 Fig.2 Effect of carbon content and GBCD control on distribution of the number of IGSCC (a) C-doped Number of IGSCC per specimen Depth of IGSCC, d/µm 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 (b) C-free GBCD uncontrolled GBCD controlled respectively.
The IGSCC predominantly propagated along random grain boundaries.

There was a coarse-grained ring in the aluminum alloy extruded bar.
Therefore, the surface grains of extruded aluminum alloy bars are more likely to recrystallize, and some of them even swallow up the surrounding grains.
However, it grows rapidly and forms coarse-grained structure, named as coarse-grained ring.
The fracture dimples of the tensile samples are shallow and the number of dimples is small, as shown in Fig. 4 a).
The fracture dimples of the tensile samples are deep and the number of dimples is large, shown in Fig. 4 b).

For instance, the electrodepositing coat of Ni has only mechanical embedment effect on grains and matrix, so it can’t supply enough bonding force for its interface with grains and matrix.
But little effects have been obtained and abnormal breaking off for grains cannot be effectively controlled.
Fig.1 Topography of the brazed diamond grain Fig.2 Different resultant at the brazing interface As can be clearly seen from Fig 1, the topography of single brazed diamond grain, there is a typical appearance of soakaging and climbing of brazed bonds surrounding the grain along the diamond surface.
Fig.3 Monolayer brazed diamond tool samples Journal Title and Volume Number (to be inserted by the publisher) 9 The monolayer brazed diamond tools with optimum grain distribution to have been developed triumphantly in our lab cover with almost all series of tools including milling, shearing and drilling cutting, which settles a foundation for further industrialization exploitation.
The size, number, form and distribution characterization of resultant at the brazing interface under different brazing conditions was discovered and the brazing mechanism for diamond was illuminated. 2.

The microstructure is composed of quasi-polygonal ferrite grains, whose average grain size is about 4μm.
Large number of nanometer TiC particles distribute along dislocations.
Grain size has been measured by image analysis software and the average grain size is about 4.0μm.
Large number of nanometer particles and high density dislocations exist in ulta-high strength steel.
(2) A large number of nanometer particles distribute along dislocations.

In one time step Δt, with decreasing casting temperature, overcooling is increased δT, new nucleating number in unit volume can be calculated: (9) Nucleating ratio is given: (10) Vc is whole simulation volume.
For clearly observing evolution of grain growing, only four grains are limited to survey.
Simulation result of grain growing at solidified time 9.0s is shown in Fig. 2(b), grains begin to grow, although dendrite envelop is limited, the arm of four grains are still continuous grow.
During to short solidified time, arms of dendrite of four grains are small, around four grains, heat transfer condition almost has no difference, so grain appearance is an equiaxed grain.
Simulation result of grain growing at solidified time 15s is shown in Fig. 2(c), four grains is grew up, with increasing solidified time, solidification circumstance for four grains are not identical, therefore grain growing velocity appear deviation, as shown in Fig. 2(c), grain with marking ‘a’ has fast growing velocity, and its dendrite arm size is more big.