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In either case, the scale of the structure is determined in the first instance by the number density of effective nucleation sites.
In the case of grain structure, grain growth must subsequently be controlled to sustain refinement and ensure thermal stability.
Control and Stability of Grain Structure Cast Alloys.
Effective grain refinement is considered to correspond to an average grain diameter of <200µm and normal cast grain sizes are typically not less than 150-200µm [7].
Refinement of grain size and stabilisation of refined grain structure remain key research targets in wrought Al alloys [9].

Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman.
A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain.
The characteristic length is inversely proportional to a so called brittleness number B [3]: . (5) In Eq. 5 L is a significant specimen dimension.
Fig. 1: Schematic drawing of wedge splitting test according to Tschegg [4,5]; numbers and symbols are explained in text.
The Matrix contains the majority of the porosity, strength of the matrix and especially the grain/matrix interface is expected to be considerably lower than that of the grain.

At the same time the electrolysis parameters are introduced into the dynamic number of effective grits with analysis its electrochemical action.
However the study of the relationship between electrical parameters and the number of effective grits is rare.
（3） Where the meaning of is same as Eq. (1). 2.2 All the active grain’s number and the total value of all simultaneous chip cross-sections for unit grinding width .
Furthermore contains the coefficient of grain’s density , so the omitted can be reflected by .
Through analysis the impact of ELID grinding on the number of the active grains, the ELID electrolysis parameters are introduced into the active grain’s number.

Introduction Grinding is a special machining process with large numbers of parameters influencing each other, which can be considered as a process where thousands of irregular cutting edges interact simultaneously with the workpiece at high speed.
From this point of view, a number of single grit micro-cutting tests were conducted [1, 2].
The abrasive grain is a conically shaped diamond grain with apex angle of 140◦ and nose radius of 0.06mm.
Grain/Work Interface 2.
The values of the critical depth of cut are, therefore, effective for separating the cutting grains and plowing grains when the grain-workpiece engagement condition is determined from grinding kinematics simulation. ����������������_��������������_���������� = ��������������_����������/�� (3) where, Ac is the cross-section area of the grain, as shown in Fig. 2(a).

Wear characteristic of SFAT presented mostly blockage and little grain-off occurred in dry status; mostly grain-off and little blockage presented in wet status.
It conceived that a tool as general grinding wheel composed of abrasive grains, pore and bond material, but the bonding strength is weak enough that, when a large grain enters the machining area (the gap of workpiece and working area of the tool), the abrasive grains near to the large grain will move to form accommodating space for the large grain and trap it in.
The load is not carried by a small number of large grains, but by a large number grains including the large one.
Material removal rate was gradually decreased in the fore 30 minutes, from 40 to 60 Porosity Bond Grain Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Porosity Grain Bond Debris Truer Grain Non-work area SFAT work area water minutes; material removal rate had little changed.
While SFAT in wet status lapping wafer, debris number that embedded into the work area were not as much as that in dry status, a large number of grains would be carried off SFAT surface by water, material removal and surface roughness remained little change.

Microscopic residual stresses within a grain were investigated in order to clarify the constraint of deformation by grain boundary.
The grain boundary exists at the central portion of two crystals.
We observed that the line width is large at the grain boundary and decreases in the region apart from the grain boundary.
In spite of a small number of data points, it can be seen that residual stresses in three crystals are clearly different from each other and a tri-axial state was observed.
Acknowledgement This work was supported by JSPS KAKENHI Grant Number 210095.

It is recognized that main reasons for grain growth in UFG materials are the enhanced grain boundary energy and high grain boundary mobility [6].
The average grain size D was calculated by the results of diameter measurements of over 100 grains.
According to observations in optical microscope the average grain size in the initial coarse-grained samples after solid solution treatment and water quenching was about of 40 mm.
The stress amplitude as a function of the number of cycles for the АK4-1 processed by combined HPT.
Valiev // In: Ultrafine Grained Materials IV.

On the criterion of precession of the location result, there are fine-grained locating and coarse-grained locating.
The cost of coarse-grained locating is much lower.
Take the number 0 grid shown in Fig. 3 for example, its level 1 adjacent neighbor grids are the grids that immediately adjacent to it, namely, grids number 1~6.
And its level 2 adjacent neighbor grids are grids number 1~18.
Number 7~18 grids are immediately adjacent to number 1~6, and their neighbor interval to grid 0 is 1.

In this study, attempts have been made to suppress the IGF of both types by (a) controlling precipitate microstructure on grain boundaries by quench control and (b) controlling grain boundary morphology by strain induced boundary migration.
Considering that the precipitation at GBs are always preferred to the precipitation inside the grain, the two C-curves for GB and grain interior precipitations are located as illustrated in Figs. 1 (a) and (b).
Fig. 4 Number of GBs with SIBM, NSIBM, and grain sizes in L and ST directions, dL, dST, respectively, as a function of true strain (cold reduction) prior to solution treatment in 7CN.
To evaluate the degree of SIBM, number of GBs with SIBM per unit area, NSIBM, was measured, and plotted together with grain size in Fig. 4 as a function of true strain.
Comparing this graph with Fig. 4, specimens cold-rolled 11% has almost the same grain size as 0% rolled specimen, but has NSIBM (number of grains with SIBM) of about 10 mm-2, which is naturally zero in 0% specimen.

ORIENTATION GRADIENTS IN a-FIBRE GRAINS OF COLD ROLLED IF STEELS P.
The plastic response of the rotated cube grains under cross-rolling (total reduction 60%) revealed the occurrence of a certain crystal fragmentation process located at the grain boundaries of rotated cube grains.
In the present investigation in-grain strain heterogeneities are observed in rotated cube grains (cf.
For the present calculation the number of grain boundary planes is limited to those being representative of the lamellar microstructure resulting from a plain strain compression deformation (i.e. rolling deformation).
Acknowledgements This research was carried out under the project number MC5.07294 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl).