Search results

This is due to the reduction ratio is too small will increase the recrystallization temperature of the finished composite foil, high temperature brazing leather material before melting recrystallization process has not been completely, the skin material in Si along the unfinished recrystallization region a large number of grain boundaries in diffusion to the core, the tensile strength of the composite foil as well as anti-sag performance, drastically reduced.
If the reduction ratio is too high will result in the fine grain size, grain boundary increased.
Composite foil brazing, high temperature state a large number of grain boundary creep, so that the anti-sag performance of composite foil rapidly deteriorating. 10 15 20 25 30 35 40 45 50 55 60 0 1 2 3 4 5 6 7 8 9 10 11 12 /mm Finishing pressure rate /% Drooping value Figure 3.
Effect of annealing temperature on sagging resistance of composite foil During annealing, recrystallization, grain growth and diffusion behaviors occur simultaneously.
As the annealing temperature, the recrystallization grains gradually grow up, and the leather material A4045 Si diffusion core material A3003.

The sample number and the position intercepted were shown in the figure 1, No 1 located in the area of C, No 2 and No 3 located in the area of B, No 4 and No 5 located in the area of A.
In the microstructure, the original austenite grain had great difference in size.
And the result of grain size was 3.5 degrees according to the ASTM E112, while the actual austenite grain was coarse.
It can be inferred that forging or quenching high temperature was close to the austenite grain coarsening temperature.
Forging heating temperature is too high, leading to larger grain structure, which is the main reason for axial cracks

Because of a large number of PCM tests regulated by standards, the tasks of reduction of the time and labor intensity of specimen testing and manufacturing are relevant [8, 9].
Diagram for determination of shearing strength Experimental data show that PCM shearing strength along the grain t0,90 exceeds the strength across the grain t90,0 [25, 26] several times.
For the structure of 0°, 90°, +45° and -45°, decrease in the number of stoppers will be observed exactly in these directions.
Table 1 includes the values of fiber areas in the directions, related to the total number of fibers in the main directions of PCM layers.
Properties of unidirectional package based on ELUR-008 P and binder 5-211-BN Parameter Value Parameter Value Monolayer thickness, mm 0.087 Ultimate tensile strength across the grain, [MPa] 21 Ultimate tensile strength along the grain, [MPa] 677 Ultimate compressive strength across the grain, [MPa] 210 Ultimate compressive strength along the grain, [MPa] 939 Modulus of elasticity across the grain, [GPa] 7 Modulus of elasticity along the grain, [GPa] 136 Ultimate shear strength in the laying plane, [MPa] 75 Poisson’s ratio 0.32 Shear modulus in the laying plane, [GPa] 5.5 To determine the shearing strength, we used modified specimens, i.e. round disks, similar to those developed in [25].

This is because that Mg alloys have limited ductility and poor formability at room temperature, which is associated with the insufficient number of activated slip systems.
Here, high angle grain boundaries (>15°) are marked black and low angle grain boundaries (5° - 15°) are marked white.
Small recrystallized grains can be seen formed along the shear bands (dash lines).
Low angle grain boundaries are mostly present in the unrecrystallized grains which exhibit higher KAM values.
It can be seen that the texture of the recrystallized grains is weaker than the whole structure and the unrecrystallized grains.

Introduction In recent years, a vast number of microwave devices such as circulator, phase shifter, isolator and miniaturized antenna, which requires an extremely low microwave loss had been contrived extensively due to high demand in microwave and magneto-optical industry [1].
Fig. 1: XRD pattern of single phase 3 hour milled GdIG, sintered at 1200 oC Fig. 2 (a) and 2 (b) show the micrograph of grains and the histogram of grain size distribution respectively.
The average grain size measured is ~0.84 µm.
As a result of sintering process, grain growth will eventually improve the size of grains, reduced the grain boundary and increase the crystallinity of the sample.
However, grain boundaries and pores alongside the grains would act as impediment which hinder the movement of domain wall.

Introduction The development of the industry and the increased number of cars on the roads leads to a significant deterioration of the surrounding atmosphere.
Specific doping can also provide improvement in the stability of the grain size during exploitation and annealing [32].
As a result, the grain size does not change strongly during thermal treatments and long term operation.
Consequences of the metal oxide doping are unpredictable, and therefore a choice of optimal additives is being realized just by overhaul of the large number of elements.
The large number of elements in these metal oxides makes it hard to deposit thin films with good and repeatable stoichiometric ratios.

Besides the excellent properties of matrix, fine particles play a role of dispersion and fine grain reinforcement.
China Vol.20 (2010),p. 577 ], enhancing the formation rate, refining grains, influencing phase change process and so on[[] G.
J.Alloys Comp Vol.554 (2013),p. 156 ] and refine the grains [[] Y.J.
The main parameters were B as 2T, 3T and 4T, pulses number N was fixed as 30.
Especially the influence of number of impurity atoms is of utmost importance.

An advantage of this process is that it leads to exceptional grain refinement so that the grain sizes produced by HPT are usually in the submicrometer or even the nanometer ranges.
This grain refinement provides the possibility of attaining high strength and, if the ultrafine grains are reasonably stable at elevated temperatures, it is possible to achieve a superplastic forming capability.
It is apparent that the double-swirl configurations tend to decrease in size with increasing numbers of turns.
The distances between the two centres of the double-swirls decrease from ~2.9 to ~1.5 mm when the number of turns is increased from 1 to 5.
Furthermore, if the straining is continued to a sufficiently large number of turns, as with 16 turns for an anvil misalignment of 100 mm, the double-swirl pattern disappears.

Formation of an ultrafine-grained (UFG) microstructure with the grain size less than 1 mm in metallic materials, including titanium alloys, can be attained by large straining at low temperatures (e.g. [3]).
The intensity of twinning in HCP metals is controlled by a number of factors [8].
a b Fig. 2 – Effect of temperature and chemical composition on the fraction of twinned grains in CP titanium as a function of strain (a) and the influence of the initial grain size on the fraction of twinned grains in 10% cold rolled CP titanium (b).
Another important factor intensifying twinning is initial grain size.
CP titanium rolled at room temperature to e=10% have shown a pronounced increase of the twinning activity with increase in grain size; maximum fraction of twinned grains was reached at grain size of 15¸30mm.

In this work, the effect of increasing the maximum number of texture coefficients used in the series expansion (represented by Lmax) on the prediction of texture and its accuracy is fully studied.
The present work is focused on the linkage between processing and microstructure (specifically texture) such that there is a direct analytical form linking the final microstructure to the initial with a limited number of process parameters.
Many efforts were invested to arrive at a mathematical representation of microstructure including chemical components, phases, grain shape, grain boundary orientation, crystal orientation distribution (texture) and so on.
Some properties such as embrittlement and fracture are more related to the grain boundary distribution and character than texture.
Bunge [3] pointed that when the crystal system is cubic and the sample system is orthortropic, a limited number of texture coefficients are needed to relate the texture coefficients and elastic properties, as shown in Eq. (4).