Search results

Grain size reduction is obvious.
The conclusions based on HRTEM studies of wetted grain boundaries suggest that the growth is limited by the sparse number of surface ledges or grain boundary dislocations that serve as attachment sites.
Such a roughening effect is equivalent to decrease of edge energy, so that the number of grains which can grow increases rapidly.
The numbers in the names of the specimens denote the molar ratio CaO/SiO2 (e.g.
Acknowledgement The support of this work by the Marie Curie Fellowship under contract number HPMF-CT2002-01878, the Slovak National Grant Agency under the contract N o 2/6181/26, and NATO SfP 981770 is gratefully acknowledged.

Finally taken the coarse-grained community as a starting point, we use the strategy of LPA to propagate labels through the network further.
Proposed Algorithm In this paper, for a given network, and represent the node set and edge set respectively, we calculate the similarity between two nodes and as the ratio of the number of their shared neighbors to the total number of both of them, that is: is a set contains all the neighbors of the node .
However, if the number of classified neighbors with the most same label is less than those of unclassified neighbors, that node can be regarded as a kernel, temporarily.
At the end of the Algorithm 1, all the nodes with the same label are grouped as a community implicitly, and all the communities constitute the coarse-grained community structure.
We use both modularity and accuracy as validate metrics; modularity is computed using the method in the literature[6, 7], and accuracy is defined as the ratio of the number of nodes classified correctly to the total number of nodes in the network.

Results In the as-received condition, α-Ti showed equiaxed grains mixed with elongated grains as in Fig. 1(a).
The number density of recrystallized grains, as shown in Fig. 5(b), increased with the temperature of the preceding rolling.
From the comparison of the number density of recrystallized grains in as-recrystallized state, i.e., 1600 min. at 600°C it is surmised that the average size of recrystallized grains decreased with the increase in the rolling temperature.
(a) Recrystallization kinetics at 600°C of CP-Ti rolled 60% at various temperatures between 25°C and 600°C, and (b) variation in the number density of recrystallized grains with annealing time at 600°C.
Beside, the increase in the number density of recrystallized grains in the warm-rolled specimens, Fig 5(b), suggests that the microstructural heterogeneity introduced by diverse slip systems yielded additional nucleation sites.

With increasing number of cycles, deformation increases further, and the stress concentration of the twins cannot be released.
Fig.7 Low cycle fatigue life versus grain size is for IN718 alloy Under low cycle fatigue alternative load conditions, different grains have different slip system orientations, where in slip cannot continuously move from one grain to another grain.
The dislocation slip occurred before restarts, then dislocation moves from the grain and the crack extends from one grain to another grain.
During the crack growth process, the stress state at the crack tip and stress intensity factor are different, leading to a different active slip number and slip band.
Acknowledgments The authors would like to acknowledge the financial support of the National Important Base Research and Development Program of China under Contract Number 2010CB631203.

A novel fault localization technique based on fine grained slicing spectrum is proposed in this paper, which can increase the efficiency of fault localization.
This technique analyzes the reliance information under fine grained level, and selects the check points which are prone to be faulty, and the faulty statements is located according to the suspicious result.
TotalPassed is the number of total passed executions, and TotalFailed is the number of total failed executions.
We select a number of target programs as the experiment target.
The method proposed in the paper will locate the faulty statements according to the order of suspiciousness, thus, the real effect can be valued by the number of statements called by the executions, that is: Scale= s|P| where s is the number of statements called by the real faults according to the suspiciousness, |P| is the number of statements contained in the program P. the smaller the value of Scale is, the less the number of statements that needed to locate the faults, and the higher the efficiency is.

There are a large number of dislocation tangles which distribute near the grain boundaries that form the sub-grain although the cellular substructure is not too clear.
When the extrusion ratio reaches 50, quite a number of dislocation tangles distribute around the second phases.
In this case, the number and the size of recrystallized grains are both increase (Fig.5(c)).
When the deformation is low (λ=12, 25), a large number of intra-crystallinedislocationsform the dislocation wall through the dynamic response at first.
The crystal orientation of sub-grain which are exist in this area do not match each other so that there are a large number of dislocations around the second phase particle which could supply the more driving force to dynamic recrystallization as the proceeding of hot extrusion compared with other place [18, 19].

Applying forced melt flow results in the formation of small grains in the centre part.
Their large spectrum in colors represents very different orientations of the grains.
To classify the flow type for different rotational frequencies the magnetic Taylor number is used.
This number denotes the ratio of Lorenz forces and viscous forces in the melt and can be calculated as 2 42 pt ru © ©©©© ?
If the height of the melt column is larger than its diameter, the critical Taylor number converges to a value of about 3700.

Superplastic Sinter-forging of Fine-grained Si3N4-Si2N2O Composite at Low Temperature J.T.
SEM experiment conforms that the average grain size of sintered body is less than 300nm.
A number of researchers have demonstrated superplasticity in several silicon nitride ceramics by applying the transient liquid phase[3,4], using ultrafine β-phase powders[5,6], or by adding secondary phases into Si3N4 to refine the microstructure[7].
Alternatively, at constant stain-rate, the forming temperature can be decreased with smaller grain size.
Microstructures of as-hot-pressed materials are very fine and uniform, with average grain sizes about 300nm.

Furthermore, studies on the templated growth of elongated grains showed that, the number of initial stable seed crystals is the dominant factor for microstructure control,regardless of shape and size of the crystals [13].
Dimensions of the grains were determined by using UTHSCSA Image Tool measuring over 200 grains in each system.
Although microstructure of unseeded α-SiAlON has also exhibited elongated grains according to the Sm 3+ existance, increase in the number of the elongated grais is obviously observed by microstructural characterisation in both seed and powder nuclei containing samples.
And in the last step according to the grain boundary phase amount, since the grain growth is somewhat diffusion controlled, α-SiAlON grains start to grow.
Indentation fracture toughness values of the samples Conclusions In this study, the substitution of powder nuclei with seeds is investigated and the results were compared: � Addition of both α-SiAlON seed and powdered Y-Sm/α-SiAlON as a nuclei resulted in the increase of the number of elongated grains and the aspect ratio

The material adopted in the present work is the coarse-grained CP iron with a number of micro-voids pre-existing at grain boundaries (GBs).
Tanaka [19] has reported that the fractal dimension of the fracture surface profile was correlated with that of the grain boundary when the grain boundary was fracture path.
The initial microstructure of the CP iron consists of large size grains (~200mm) and a number of micro-voids (in the size of several microns) pre-existing at GBs, as shown in Fig. 1.
Experimental results and discussion The cyclic stress response curves of the coarse-grained CP iron at different Dεt/2 are presented in Fig. 2.
With increasing number of cycles, the specimen undergoes a continuous cyclic hardening and no saturation stage occurs due to a continuous crack propagation as a consequence of strong interactions between dislocations and micro-voids at GBs.