Search results

There are some recrystallized grains mixed in coarse deformed grains.
At 400°C, a large number of small recrystal grains generate in deformation structure, most of them are round and of uniform distribution.
The average grain size increases as strain rate bigger than 1s-1, at higher strain rate, the number of recrystallization grains is smaller for some deformed grains have not triggered recrystallization.
Thus increasing the number of dislocation sources per unit volume in a grain, aggravating the trend of dislocation tangle simultaneously.
The growth of recrystallization grains is finished by combining the grains.

The initial microstructure of the sample B is shown in Fig.1b, in which a large number of fine precipitated particles are smaller than 1mm.
In Fig.2a, a larger number of uniform distribution second-phase particles can be observed.
In addition, some of original grain boundaries become bent or waved, which suggests that sub-grains may be formed along grain boundaries.
It can be seen that original grains elongated and a few recrystallized grains can be observed along grain boundaries when the height reduction is 60%(Fig.4a).
From Fig.5c, it can be seen that a large number of sub-grains retained in the elongated grains.

This work is funded by the National Science Foundation under Grant Number DMR-0517351.
Titanium alloys have a number of properties that make them desirable for many applications.
Large-grained alloys (>200 µm) show extensive slip and twinning, while small-grained alloys (<100 µm) deform solely by slip.
%V alloy at 95% YS as a function of grain size.
It has been found that a number of factors affect twinning during low temperature creep.

The presence of defects in the form of cavities and porosities were also observed at the grain boundaries.
In between, columnar grains are present with different sizes and orientations.
Fig. 3 presents the SEM micrograph of a cracked zone where four cracks, numbered C1, C2, C3 and C4, can be distinguished.
On the other hand, the number of P2 pores is higher than that of P3 pores.
Based on their morphology, they could be considered as grain boundaries and/or secondary microcracks.

The change of the damping properties of graphitic steel caused by thermomagnetic treatment is relatively small, due to a large number of diamagnetic inclusions of graphite and quite fine-grained ferrite matrix.
This is explained by high density of diamagnetic graphite inclusions in a relatively fine-grained ferrite matrix (the average grain diameter equals to about 20 μm).
The sources of enrichment can be, firstly, segregation of Cr atoms at the grain boundaries, which are diffused throughout the grain body under thermomagnetic treatment, which is most likely in the fine-grained alloys; and, secondly, inclusions dissolve under thermomagnetic treatment.
The numbers on the distribution function of ultra-fine magnetic fields (Fig. 3) in the order 1–9 correspond to atomic interactions: Fe-Fe, Fe-Cr2, Fe-Cr1, Fe-(Cr1,Cr2), Fe-(Cr1,2Cr2), Fe-(2Cr1,Cr2), Fe-(2Cr1,2Cr2), Fe-(2Cr1,3Cr2), Fe-(3Cr1,2Cr2), where the index 1 or 2 is the number of the coordination sphere in which Cr atom is located, and the numerical coefficients are the quantity of Cr atoms in these coordination spheres.
In graphitized high carbon steels with ferrite-graphite structure, the change in damping properties as a result of thermomagnetic treatment is quite insignificant, which is explained by a large number of diamagnetic graphite inclusions in a relatively fine-grained ferrite matrix. 3.

Fig. 2 is the relationship of elongation versus the number of ECAP pass.
The curve of elongation versus the numbers of ECAP passes.
It can be seen that after conventional extrusion the alloy has coarse grains and there are a lot of precipitates on grain boundaries and only a few in grains.
It can be seen that the ZK40 processed by 1 pass has the largest number of precipitates, and the number of precipitates of ZK40 processed by 4 passes is smallest.
Because the precipitates in the microstructure hinder grain boundary sliding, the ZK40 processed by 1 pass with the largest number of precipitates shows greatest flow stress in the three conditions.

Thus, the number of nuclei in unit time is increased.
Therefore, the number of crystal nucleus is also increased per unit volume.
Because there are more nucleated grains at 900℃, the austenite grain mainly grows in cooling process.
The nucleus density after finishing rolling at 950℃ is higher than that at 900℃, and the nuclei number increases with increasing cooling rate.
With increasing cooling rate, the undercooling is increased and the nucleation energy is decreased, which accelerates the formation of austenite nucleus, thus the number of recrystallization grain increases and grain size decreases.

The {001}<110> textures transform to the {001} texture after cold rolling, in this process the grains divisional are analyzed by the HEXD result.
On the other hand, investigations associating with the deformed microstructure in IF steel sheet were focused on the substructure, e.g. subgrain size, orientation and configuration of the grains etc.
Fig. 2 the metallographic photos of different cold rolling reduction (a) 0%, (b) 20%, (c) 40%, (d) 60%, (e) 80% As shown in Fig. 2, it is can be found that the grains shape change form equal axis to elongate, when the reduction up to 80%, a large number of dislocations and sub-grains appear in some elongate grains, which demonstration the deformation in the grains is heterogeneous.
Fig. 3 the texture development of cold rolling Iron sample (a) 0%, (b) 20%, (c) 40%, (d) 60%, (e) 80% During cold rolling, three characters of the grains are distinct, grain shape, orientation and subgrain form.
The HEXD can provide the evidence of the grains break in the cold deformation process.

Fig.1 Original grain for hot rolling sheet Fig.2 Grain in air cooling after heated to 900˚C Fig.3 Grain after imposed pulsating in austenite region Fig.4 Grain after imposed pulsating in ferrite region Seen from Fig.1, the initial fine grain size of hot rolled coil is about 12μm (10 grades).
The grain grow bigger after being heated.
Its growth of grain strip is more obviously compared to Fig.2.
The austenitic grain tends to uniform and large-angle grain boundaries after being imposed pulsating micro-magnetic radiation (100mT). 2.
In the tensile test, the mechanical property is in accordance with the grain size, it decreased obviously when the grain become larger.

Commercial varistors are generally made of sintered ZnO powder mixed with a number of other oxides such as Bi2O3, Sb2O3, V2O5, Pr6O11 etc.
The breakdown voltage of a varistor is inversely proportional to the grain size [2] which means that a higher breakdown voltage can be achieved simply by reducing the grain size [3].
Considering at least ten digitally acquired SEM images, the average grain size (d) of ZnO has been determined by linear intercept method using the formula [7]: d = 1.56 L / M x N (1) where, L is the random line length on the micrograph, M is the magnification of the micrograph, and N is the number of the grain boundaries intercepted by a line.
Secondary phases appear primarily at the grain boundaries and nodal points; however, occasional presence within the grains has been observed for 2 mol.% Er2O3 added specimen (Fig. 1(c)).
The microstructure of sintered pellet consists of ZnO grain and intergranular (V, Mn and Er-rich) secondary phases that exist primarily along the grain boundaries and triple points.