high-temperature isothermal annealing

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Effect of heterogeneously distributed pre-existing dispersoids on the recrystallization behavior of a cold-rolled Al–Mn–Fe–Si alloy

Effect of heterogeneously distributed pre-existing dispersoids on the recrystallization behavior of a cold-rolled Al–Mn–Fe–Si alloy

preferentially at high-angle grain boundaries and subsequently also on low-angle grain boundaries, before the onset of recrystallization and during recrystallization [8]. Both types of boundaries are aligned with the RD direction, as can be seen in Fig. 2. Nucleation at grain boundaries is thus largely suppressed, and only a few orientations (P-, M-oriented grains) can grow out of the deformation zone near the constituent par- ticles, which fi nally leads to strong M or P texture components. The rea- son is their special boundary characteristics/orientation relationships with respect to the surrounding deformed matrix (with a typical rolling texture) making them less affected by concurrent precipitation [7,8], and moreover that they have an advantageous orientation relationship for growth [13]. The strength of the M texture component is stronger than that of the P texture component when recrystallization occurs at 350 °C, see Fig. 6a and b. This is in agreement with earlier work by Liu and Morris [12] in which the evolution of recrystallization texture in a supersaturated Al – Mn alloy was investigated at different temperatures. At the very high annealing temperature of 500 °C, recrystallization com- pletes quite fast before signi fi cant concurrent precipitation occurs, and none of these three texture components (M, P and ND-rotated cube) are strong (see Fig. 4a). Interestingly, even though a large amount of dis- persoids was present along the grain/sub-grain boundaries (see Fig. 2b) before the onset of recrystallization, a very weak texture was still ob- tained, as illustrated in Fig. 4b. The reason could be that all nucleation mechanisms are mainly still active at high temperatures (controlled by thermally activated processes), and although a certain effect in Fig. 4. ODF maps showing the recrystallization textures after annealing of the deformed samples. a) Isothermal annealing at 500 °C for 5 s; b) Step annealing at 300 °C for 10 4
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A New Approach on the Modelling of Isothermal Recrystallisation in Cold Rolled Ferritic Steels: An Application to Back Annealing of Low Carbon Sheet Steels

A New Approach on the Modelling of Isothermal Recrystallisation in Cold Rolled Ferritic Steels: An Application to Back Annealing of Low Carbon Sheet Steels

demanded it is achieved by either alloying the steel or by special heat treatments at higher temperatures. The above procedure entails wastage of energy and increased costs. On the other hand, by controlled low temperature annealing, it is possible to retain as much of the strength from cold rolling as possible while at the same time restoring adequate ductility. This allows to yield a material with properties that are a compromise between the high strength–low ductility of fully cold rolled sheet and the low strength–high ductility of fully recrystallised sheet. This process is variously termed as ‘back annealing’, ‘partial annealing’, ‘recovery annealing’, ‘stress relief annealing’, ‘temper annealing’ or ‘controlled incomplete annealing’. Basically, the process consists of two stages, deformation and annealing. It is in this context where the proposed model presented in this paper could be very useful to determine the annealing conditions required to reach a certain recrystallised volume fraction.
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STUDY ON THE PRECIPITATION KINETICS OF ORDERED PHASE IN Ni-10 at% Cr ALLOY

STUDY ON THE PRECIPITATION KINETICS OF ORDERED PHASE IN Ni-10 at% Cr ALLOY

Significant progress in the study of homogeneous second phase precipitation in alloys has been achieved in the last decade because of the applications of modern serious microscopic techniques to explore the early stages of phase precipitation. It has been established [1-3] that the later stages of precipitation in binary alloys can be described in terms of a simple picture as microstructural evolution. The real materials may not be always homogenous because various types of lattice defects like vacancies, dislocations and domain boundaries might be involved. The precipitation of second phase in alloys was found to be enhanced with the existence of these lattice defects in alloy matrix [3]. The precipitation of second phase in a matrix produces structural changes and the new phase introduces elastic strain, which changes the kinetics of precipitation [4]. The grain boundary precipitation was accelerated by increasing temperature above 800 ºC. It was developed very fast and can be formed at very short time [4]. Grain boundary precipitation also causes embrittlement of the alloy. The rate controlling processes for this phenomenon are the volume and the grain boundary diffusion of chromium in the alloy matrix [5]. Accordingly, controversial results on the behavior of the kinetics of precipitation were reported [6]. It is established that the electrical and magnetic properties are very sensitive to structural changes due to the grain- boundary precipitation [7-9]. The precipitation phenomena of chromium in nickel is caused by isothermal annealing at high temperature [10].
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Al) as an Alternative Automotive Body Material

Al) as an Alternative Automotive Body Material

Providing better performance with reasonable cost to the end user has been the main aspiration to most of the car manufacturer in today’s era. The requirement for a better performance to the end user are detailed as follow; tomorrow’s car will handle better, lighter, more fuel efficient and cause less pollution. One of the convenient design strategy used in enhancing the vehicle efficiency is via light weighting. As a known fact that light weighting is not only enhances fuel efficiency, but also reduces the emissions from automobile and improves the performance of driving. The major drawback in implementing light weighting is that the manufacturer has to pay more on the cost for it. It was proves that intermetallic aluminides has appeared to be as one of the material having high potential for a wide range of technological application in some of the essential areas. This enormous potential of intermetallics especially aluminides was contributed from their own mechanical properties such as high resistance to oxidation and corrosion [1]. It also has relatively low density which adds up to the ability to sustain strength and stiffness at elevated temperature [2]. In addition, there were voluminous research on intermetallics has been carried out to investigate the potential properties in aluminides especially the Ni-Al systems [3-6]. Due to the potential of having high resistance towards corrosion and good mechanical properties, enable nickel to be as one of the materials used in structural and
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Shrinking of Solid state Nanopores by Direct Thermal Heating

Shrinking of Solid state Nanopores by Direct Thermal Heating

tive ion etching (RIE) using tetraflouromethane at 100 W and gas flow rate of 15 sccm. The etch rate of the RIE was characterized using a reflectometer (Ocean Optic, Dunedin, FL, USA). All samples were cleaned with piranha solution before FIB (Carl Zeiss, Peabody, MA, USA) drilling. The free-standing oxide membranes were drilled with the FIB to create the initial pores. The FIB process was optimized first in terms of drilling time and milling current while the acceleration voltage of 30 kV was fixed. HRTEM (Hitachi High Technologies America, Inc., Schaumburg, IL, USA) operating at 300 kV was used to image the nanopores and to charac- terize their diameters.
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Controlled electromigration on vicinal surfaces

Controlled electromigration on vicinal surfaces

With the appropriate electric field at high temperature, as the annealing time is extended, the surface morphology steadily progresses through successive stages; from single atomic steps[r]

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Role of microstructure and surface defects on the dissolution kinetics of CeO2, a UO2 fuel analogue.

Role of microstructure and surface defects on the dissolution kinetics of CeO2, a UO2 fuel analogue.

, who showed that the dissolution of grain boundaries was influenced by the crystallographic orientation of the grains and the corresponding mean misorientation angle of the grain boundaries. Boundaries with higher mean misorientation angles were found to dissolve at faster rates than those with low mean misorientation angles; it was hypothesised that higher misorientation angle grain boundaries contained a greater proportion of defects, with a high reactive surface area, which led to the enhanced dissolution rates. This study and others 17,18, have highlighted the important role of grain boundaries, and particularly their association with defect structures (e.g. oxygen vacancies) on dissolution processes in spent fuel analogues. This underlines the requirement for new methodologies capable of linking grain boundary structure with dissolution kinetics, to fully understand their role in the dissolution of spent fuel materials 42 .
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Determination of the Formation of the 1/6[031] Extrinsic Stacking Faults in Deformed YBa2Cu3O7−δ

Determination of the Formation of the 1/6[031] Extrinsic Stacking Faults in Deformed YBa2Cu3O7−δ

processing conditions resulted in the formation of and edge dislocations, both having a (001) slip plane. Subsequent high temperature annealing at 900°C resulted in the formation of extrinsic stacking faults with a large separation of the partial dislocations, up to 0.35 μm, suggesting a very low minimum stacking fault energy of 1.2 × 10 −2 J/m 2 . High resolution transmission electron microscopy (HRTEM) in conjunction with image simulations revealed that the stacking faults were comprised of an extra CuO plane between the Ba layers with an offset of b/2. The stacking fault vector of 1/6[031] requires some separation of the Burgers vectors into the c-axis direction. A model in which [010] separates into 1/6[031] + 1/[031] is consistent with the observed stacking faults.
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Nano mechanical properties of Fe Mn Al C lightweight steels

Nano mechanical properties of Fe Mn Al C lightweight steels

Experimental results. Nano-indentation test results have been observed as function of four annealing temperatures (500 °C, 700 °C, 900 °C and 1050 °C) and two alloys compositions (Fe-15Mn-10Al-0.8C-5Ni and Fe-15Mn-10Al-0.8 C (all in wt.%)). Figure 4 shows the load-depth curves along with corresponding hardness val- ues for the bulk α and γ phases (without precipitates) as well as the composite bulk phases containing differently ordered precipitates. It is important to note that the nanoindentation technique as performed in this study is una- ble to measure the hardness of isolated nano-sized precipitates, but measures instead the hardness of the nano- sized features within a surrounding matrix, and therefore yield a compound hardness value of the matrix with particles. In the present study, we observed two B2 phase with distinct morphology: B2 with flat interfaces and sharp edges with an average size of ≈ 1.4 μ m formed in the γ -phase and disk-like precipitates with a size of a few hundred nanometres formed in α -phase. Additionally, κ -carbide formed in the γ phase had a cuboid shape with sizes of less than 100 nm and those formed in α -phase had a needle-like shape with an average size of ≈ 1.5 μ m.
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Surface Morphology Transformation Under High Temperature Annealing of Ge Layers Deposited on Si(100)

Surface Morphology Transformation Under High Temperature Annealing of Ge Layers Deposited on Si(100)

The Ge and SiGe islands grown on Si(100) undergo a strong strain due to the lattice mismatch between Si and Ge and, therefore, they are thermally unstable. The strain reduction can be achieved by the formation of more homo- geneous distribution of chemical composition by means of Si-Ge intermixing under high-temperature annealing. Annealing can also produce significant changes in the surface morphology [16]. The temperature effects were studied with respect to compositional atomic ordering and surface morphology evolution for the SiGe islands prepared by the deposition of relatively low Ge coverages (up to several nm) [17, 18]. In the first part of this work, we study the surface morphology obtained by the depo- sition of relatively high Ge coverages (30–150 nm) on Si(100) at temperatures of 400–500 °C. The obtained images of surface morphology show that, as the Ge cover- age increases, the islands merge in ridges. The effects of high-temperature annealing were studied then in order to reveal the changes in the surface morphology and in the chemical composition of the grown structures. Annealing at 800–900 °C led to the formation of two different surface areas. One of them is composed of open Si substrate windows and relatively large ridges around them. The formation of such porous SiGe layers looks like the result of strain-facilitated melting with subsequent solidification in the conditions of SiGe dewetting on Si(100). The other surface area is the continuous SiGe layer which is formed by smoothing of the grown islands or ridges with the ma- terial transfer in the areas between them. Such surface morphology transformation is accompanied by the appea- rance of a high threading dislocation concentration. The areas with two essentially different surface morphologies can coexist on the surface. The ratio between sizes of these two areas depends on the temperature and the annealing time, and it is determined by the competition between pro- cesses such as strain-facilitated melting from one side and a gradual mass transport along the surface and Si-Ge inter- mixing with Ge diffusion into the substrate from the other side.
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Comparative Study of Heat Treatment on the Optical Properties of Sb2S3 and CsCl thin Films at different Thicknesses

Comparative Study of Heat Treatment on the Optical Properties of Sb2S3 and CsCl thin Films at different Thicknesses

bandgap (Eg) was of the films 1.60ev, 1.83ev, 1.88ev and 1.33ev. By the comparative study of bandgap before and after annealing, bandgap increases with thickness. Which explain the value of the optical energy gap was affected by annealing which was decreased as the annealing temperature increase the film deposited in this work shows narrow band gap, as such it could serve as good absorber layers for photocells.

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Dependence of Atomic Scale Si(110) Surface Roughness on Hydrogen Introduction Temperature after High Temperature Ar Annealing

Dependence of Atomic Scale Si(110) Surface Roughness on Hydrogen Introduction Temperature after High Temperature Ar Annealing

Semiconductor integrated circuits are the most important hardware technology in today’s technologically ad- vanced society. Improvements in the performance of semiconductor integrated circuits have been driven primar- ily by Si field-effect transistors (a type of metal-oxide-semiconductor field-effect transistor, MOSFET), which are the smallest constituent units of high-performance circuits. To improve the performance of semiconductor integrated circuits, it is essential to enhance the current-driving ability and reduce the power consumption of a transistor. Until now, these requirements have been met mainly by scaling the transistor structure. However, scaling will face limitations in near future [1] [2], and so it is very important to establish a performance im- provement method other than scaling.
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Geometriztion of heat flow on volumetrically isothermal manifolds via Ricci flow

Geometriztion of heat flow on volumetrically isothermal manifolds via Ricci flow

During some previous years, Hamilton prepared the elementary an- notations on RF and shown that RF is an outstanding device for sim- plifying the geometric as well as topological structures of the manifold under consideration and generally speaking, RF is able to compress all the positive curvature parts (most often including Gaussian and Ricci curvatures) of the underlying manifold into emptiness until they become quite homogeneous i.e., by implementing RF on the manifold, it begins to look much the same, it doesn’t matter which one vantage point in the manifold one selects. Of course, the flow seems to isolate manifold into tremendously symmetric components. Here is an example of two dimensional manifold in which the RF always ends up intimating the manifold with a metric of constant curvature, which would be positive (as in the ellipse or sphere etc.), and the same becomes zero as in case of cylinder, or negative as in case of hyperbolic manifolds. Thus the fact that such a constant curvature with RF induced metric can always found is called the ”Uniformisation Theorem” and has a vital signifi- cance in the theory of manifolds. It is also of great interest that in case of higher dimensional manifolds, the RF can most probably build up singularities before attaining perfect symmetry, but it is also possible to remove singularities by performing surgeries on the singularities so that the manifold could again turned into smooth form and one could again restart the RF process. It is also noteworthy that surgeries can however deform the topology of the underlying manifold, for instance they might convert an arbitrary connected manifold into two disconnected varieties. 2.2. Volumetric Isothermal Manifolds. In order to target our aim of pursuing Geometrization of heat flow on volumetrically isothermal manifold via RF, let us first concisely introduce some major concepts of differential geometry and their impacts over isothermal volumetrically manifold.
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Ordered GeSi nanorings grown on patterned Si (001) substrates

Ordered GeSi nanorings grown on patterned Si (001) substrates

Ordered silicon-based nanostructures have attracted considerable attentions due to their potential applica- tions in various novel devices including field-emission displays [1], nanoelectronic and nanophotonic devices [2-4]. Nanorings are artificial ring-structure in nanoscale that confine carriers in three dimensions. Particularly, they have shown attractive properties due to their spe- cial topological configuration, e.g., large and negative excitonic permanent dipole moment [5], memory prop- erties [6] and high oscillator strength for the ground- state band-to-band transition [7]. Self-assembled nanorings [8-11] have been fabricated with a thin cap- ping layer deposited on self-assembled quantum dots (QDs) that were grown by so-called Stranski-Krastanow (SK) growth mode. However, the size uniformity of those nanorings is rather poor and their spatial distribu- tion is random as reported in literatures so far. Nanor- ings with controllable size and sites have not been reported yet.
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Effects of Spin Speed on the Photoelectrochemical Properties of Fe2O3 Thin Films

Effects of Spin Speed on the Photoelectrochemical Properties of Fe2O3 Thin Films

Figure 3 shows transmittance spectra measured by ultraviolet-visible spectrometer for samples with different annealing atmosphere. These films are highly transparent in the range from 580 nm to 700 nm. Similar result was also observed by Ismail et al [22]. The transmittance increases with increasing spin speed due to decreasing thickness (Fig. 4). The (αhν) 1/2 vs. hν plot is presented in Fig.

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Effect of Heat Treatment on the Optical Properties of CuInSe2 Thin Films

Effect of Heat Treatment on the Optical Properties of CuInSe2 Thin Films

The CIS films were deposited by thermal vacuum evaporation technique. The optical properties of the CIS films were influenced by the heat treatment (annealing) process. It was observed that the absorbance in the visible region is high. Absorption coefficient had been calculated from transmission spectra taken within the wavelength of the range (350 to 1090) nm. The absorption coefficient obtained of the order of 10 4 cm -1 in the energy region value and the rate of

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Studies on Activation of High-Mobility III-V Group Semiconductor Materials by Using Microwave Annealing

Studies on Activation of High-Mobility III-V Group Semiconductor Materials by Using Microwave Annealing

and RTA 550°C. It demonstrates that MWA 2.5P can use lower energy which actual temperature is about 450°C than RTA 550°C to achieve SPER. As the annealing energy increases, the main peaks reduce because it begins to activate the dopant electrically. The Raman spectrum results can correspond the TEM results that the annealing conditions of MWA 2.5P(1.5kW) and RTA 550°C have the highest peaks. High PL signals could correspond the sheet resistance low, and it represents that the activation level. The PL signals of MWA 2.5P and RTA 550°C has the highest peak from small signals, and it corresponds the Raman that they achieve SPER. And the PL spectrum of MWA 3P and RTA 600°C has strong signals that they start to activate dopants electrically. The PL signals of annealed samples at implantation temperature of 150°C are stronger than at implantation temperature of 80°C because the implantation temperature of 150°C can repair the amorphous layer resulting in higher dopant activation after annealing. And the best activation of the highest PL signal is located on the annealing condition of MWA 3.5P of implantation temperature at 150°C. It proves that MWA could use lower energy than RTA to achieve dopant activation effectively. From SIMS profiles of annealed samples by RTA and MWA, higher temperature of RTA 600°C causes silicon distribution deeper slightly while the silicon profiles of MWA are almost the same. It demonstrates that MWA has better ability to control dopant diffusion than RTA.
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X-RAY DIFFRACTION ANALYSIS OF THERMALLY EVAPORATED COPPER TIN SELENIDE THIN FILMS AT DIFFERENT ANNEALING TEMPERATURE

X-RAY DIFFRACTION ANALYSIS OF THERMALLY EVAPORATED COPPER TIN SELENIDE THIN FILMS AT DIFFERENT ANNEALING TEMPERATURE

were structured in mixed phase between cubic space group F-43m (no. 216) and orthorhombic space group P n m a (no. 62). The crystallite size and lattice strain were determined from Scherrer calculation method. The results show that increasing in annealing temperature resulted in direct increase in crystallite size and decrease in lattice strain.

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Enthalpy relaxation behavior of dry wood detected by temperature-modulated differential scanning calorimetry

Enthalpy relaxation behavior of dry wood detected by temperature-modulated differential scanning calorimetry

Furthermore, more enthalpy relaxation was generated in a shorter time than in isolated lignins. Figure 7 shows the effect of the annealing time on the endothermic peak temperature (indicated by white arrows in Fig. 5). The peak temperature decreased with increasing annealing time for annealing temperatures below 20 °C, while it was almost constant for annealing temperatures above 20 °C. The peak temperatures of the cellulose appeared about 20 °C higher than those of wood annealed at 0 °C, indi- cating that the cellulose possesses a somewhat rigid structure involving both crystal and amorphous. The endothermic peak temperature generally increases as enthalpy relaxation proceeds in glassy materials (including lignin and cellulose) [13–15]. The shift in the peak tem- perature in Fig. 7 differs considerably from previous results for other polymers. This difference in the enthalpy relaxation behaviors and peak temperature shifts of dry wood and its isolated components may indicate differences in the fine structure and the molecular mobility. Although wood consists of three main components (cellulose, hemicellulose and lignin), the overall structure of these components with moisture exhibits quite complex physical, mechanical, rheological, and thermodynamic behaviors. In particular, the effects of amorphous components on these behaviors are currently unclear. The compatibility between amorphous and crystalline cellulose will affect these behaviors. Most mechanical studies of moist wood con- clude that the softening behavior derived from the glass transition depend on the properties of lignin. In this study, the enthalpy relaxation behaviors of dry wood were mea- sured by DSC and transitions due to other components besides lignin were detected. Investigation of the difference between wood properties and those of isolated components may provide a new model of wood microstructure that accounts for the time-dependent physical properties on
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Nano-mechanical Behaviour and Microstructural Evolution of Cu/Si Thin Films at Different Annealing Temperatures

Nano-mechanical Behaviour and Microstructural Evolution of Cu/Si Thin Films at Different Annealing Temperatures

Following the nanoindentation tests, the specimens were annealed at a temperature of either 160℃ or 210℃ for 2 min in a rapid thermal annealing (RTA) system. During the annealing process, purified nitrogen gas (99.999%) was passed through the furnace at a flow rate of 3L / min. Thin foil specimens of both the as-deposited samples and the annealed samples were prepared using an FEI Nova 200 focused ion beam (FIB) milling system with a Ga + ion beam and an operating voltage of 30

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