Effect Of Annealing Conditions Research Articles

Effects of annealing on microstructure, composition and magnetic properties of rolled Fe/Ga-Al composite strip

The Ga liquid and Al powder were mechanically mixed and poured into a hollow iron plate, after alloying, the composite plate was rolled at room temperature for preparing an Fe/Ga-Al composite strip. The effect of annealing conditions on the diffusion, microstructures and magnetostrictive properties of the strip were studied. The composite plate had good cold rolling formability. After annealing at 750–850 °C for 5 h of the cold-rolled sample with a reduction of 97%, the diffusion distance of Ga and Al in the Fe matrix increased with an increase of the annealing temperature. However, some holes appeared in the center of the sample annealed at a temperature of more than 830 °C, which was detrimental to the subsequent rolling. The combination of the secondary cold rolling and annealing was beneficial to improve the composition homogeneity and magnetic properties of the sample. The magnetostriction coefficient (λ//) of the primary rolled sample was low, ∼4 × 10−6. After annealing and secondary cold rolling, the λ// of the sample increased to 9 × 10−6 and the λ// of the sample conducted by further annealing at 820 °C for 20 h reached 27.5 × 10−6.

Effect of annealing conditions on polycrystalline silicon produced by the inverted aluminium-induced crystallization of amorphous silicon films on glass substrates

The effect of various annealing treatments on the structure properties of crystalline silicon (c-Si) produced by the inverted aluminium induced crystallization of amorphous silicon (a-Si) films was studied. The surface morphology and grain size of c-Si films were observed by optical microscope and scanning electron microscope. X-ray diffraction and Raman spectroscopy were used to study quantity of Si crystallization due to thermal annealing. Results showed that the c-Si with an average grain size of 54 nm in a (111) orientation was obtained by the thermal annealing at 350 °C for 1 h. Prolonged heat treatment improved Si crystallite quality and increased the average grain size.

Effect of annealing conditions on the structure, phase and granulometry composition, and reflectance spectra and their changes on irradiation for calcium silicate powders

High-temperature annealing of hydrated forms of calcium silicate produced in the multicomponent system CaCl2Na2SiO3H2O yields the formation of a heterophase structure containing high-temperature phases of pseudo-wollastonite and silica. Under these conditions, it is observed that there is an increase in the calcium silicate crystal lattice energy, particle size, reflection coefficient in the visible and near-IR spectral ranges, and radiation stability of the synthesized powders. The improved characters make the work useful, interesting and important.

Effect of ART-Annealing Conditions on Microstructural Regulation and Deformation Behavior of 0.17C-9Mn-3.5Al TRIP-Aided Steel

The effects of annealing conditions on the microstructure and deformation mechanism of 0.17C–9Mn–3.5Al steel have been investigated. Through austenite reverted transformation (ART) annealing, a multiphase microstructure composed of δ-ferrite, α-intercritical ferrite, γ-austenite, and α'-martensite is obtained in as-forged specimens. For the specimen annealed at 750 °C for 60 min, a high volume fraction (42.19%) of retained austenite is attained, yielding a large total elongation (TE) of ≈38% and tensile strength (Rm) of ≈810 MPa and a two-stages work hardening behavior. The work hardening behavior analysis using the differential C–J model clarifies that the multistage can be mainly attributed to the discontinuous transformation induced plasticity (TRIP) effect, which is related to the volume fraction of retained austenite and its different stability levels as well as cooperative deformation of the multiphase microstructure. Thus, the active TRIP effect predominately affects the high strain stage, resulting in a higher work hardening ability and a increased plasticity.

Effect of annealing conditions on the molecular properties and wetting of viscoelastic bitumen substrates by liquids

Typically, in the production of asphalt concrete, bitumen and mineral aggregates are heated and mixed at temperatures above 100°C. After the mixing process bitumen ideally coats the mineral aggregates and remains in the form of thin films. Because bitumen is highly temperature sensitive, the study of its properties in terms of chemistry, microstructure and rheology as a function of different annealing conditions is very relevant. The resultant molecular properties have a direct correlation to bitumen macroscopic response to liquids such as water, which is of extreme relevance to the understanding of the detrimental effect of water on asphalt pavements. The wetting characteristics play a crucial role on the extension of detachment of bitumen from the mineral aggregates when asphalt is exposed to wet conditions. Therefore, in this work, the effect of the annealing temperature and cooling history on the chemistry, microstructure and wetting of bitumen films was studied. Crystalline microstructures were identified in bulk and on the surface of the bitumen films. Larger crystals presenting higher crystallinity degree were identified when the annealed bitumen films were cooled slowly. Moreover, higher annealing temperatures increased the oxidation level. The change of the rheological properties due to the alterations of the annealing conditions produced changes in the wetting characteristics. For instance, the advancing motion of a liquid drop on the viscoelastic bitumen substrate presented an intermittent behaviour due to the deformation of bitumen at the liquid-bitumen-air contact line. Consequently, changes in the contact angles were also observed.

Tailoring of Magnetic Properties and Magnetoimpedance Effect in Thin Amorphous Wires

We have studied the effect of annealing conditions on magnetic properties of amorphous CoFeNi-based glasscoated microwires. We show that annealing can be very effective for manipulation the magnetic properties of amorphous ferromagnetic glass-coated microwires. Low coercivity and high giant magnetoimpedance (GMI) effect have been observed in as-prepared Co-rich microwires. After annealing of Co-rich microwires we can observe transformation of inclined hysteresis loops into rectangular and coexistence of fast magnetization switching and GMI effect in the same sample. We demonstrate that the switching field value of microwires can be tailored by annealing in the range from 4 to 200 A/m.

Effects of annealing conditions on resistive switching characteristics of SnOx thin films

A resistive random-access memory based on an Al/SnOx/Pt structure is demonstrated. The SnOx thin films were prepared by DC sputtering at room temperature and different post-deposition thermal treatments carried out. We observe a significant improvement of bipolar resistive switching characteristics after annealing at 300 °C in nitrogen. The obtained memory devices show good stability with a relatively long retention time, exceeding 105 s. The resistance ratio remains above 55 within the duration of 100 endurance cycles. An interface modified space-charge-limited-current model is proposed as a possible switching mechanism. The achieved characteristics of the resistive switching in SnOx films seem to be a promising candidate for nonvolatile memory applications.

Effect of annealing conditions on the structural, electrical and optical properties of Li-doped NiO thin films

Transparent conductive oxide (TCO) p-type Li-doped NiO thin films were deposited on the (0001) sapphire substrates by magnetron sputtering technique with a high purity NiO:Li2O ceramic target. We systematically investigated the structural, electrical and optical properties of NiO:Li thin films annealed in different conditions. We found that annealing in different conditions greatly affects the physical properties of NiO:Li thin films. Compared with the NiO:Li thin film annealed in oxygen, the hole concentration of NiO:Li thin film annealed in nitrogen at the same processing temperature is obviously lower. Annealed in oxygen at 500 °C, NiO:Li films show excellent crystal quality with single (111) orientation, high hole concentrations. When the annealing temperature increased, the transmittance of NiO:Li thin films become better for wavelength range from ultraviolet (UV) to visible with a significant absorption edge near 350 nm.

Correlation between wheat starch annealing conditions and retrogradation during storage

Yu K., Wang Y., Xu Y., Guo L., Du X. (2016): Correlation between wheat starch annealing conditions and retrogradation during storage. Czech J. Food Sci., 34: 79-86. The effects of annealing conditions on the degree of retrogradation (DR) in wheat starch were analysed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Three annealing parameters were varied, namely moisture (50-90%), time (0.5-48 h), and temperature (35-50°C). These factors had different impacts on the DR. The results suggest that 25% (w/v) annealed wheat starch samples stored at 4°C for 7 days had smaller DR values than native wheat starch under the same storage conditions. XRD indicated that annealed wheat starches stored at 4°C for 7 days had fewer recrystallisations than native wheat starch. Optimised annealing conditions can be used to control the structural and mechanical properties of certain starch-based products, such as in the production of bread, since retrogradation results in staling and reduced digestibility.

Effects of annealing conditions and film thickness on electrical and optical properties of epitaxial Al-doped ZnO films

Epitaxial films of Al-doped ZnO were grown at 400°C on sapphire-R substrates at atmospheric pressure via the aerosol-assisted MOCVD technique. The film microstructure, surface morphology, and electrical and optical properties were investigated in relation to the annealing temperature (300–600°C), gas atmosphere (argon–hydrogen mixture, argon, nitrogen, vacuum, oxygen, and air) and film thickness (~70–1200nm). The annealing influenced the carrier concentration and mobility in the films, producing an enlarged effect at higher temperatures, whereas the crystalline quality and surface morphology of the films were nearly unaffected by annealing. The electrical properties of the films markedly degraded after annealing in oxygen and air, and improved when annealed in other gas environments. The largest improvement of the electrical properties was obtained by annealing of films in the argon–hydrogen mixture. The rapid evolution of film properties with thickness was observed in the range of small thicknesses (~70–170nm). The film properties were nearly unchanged for further increases in the film thickness up to ~800nm, whereas thicker films exhibited degraded electrical properties due to their partial cracking. The effect of the annealing on film electrical properties increased with the decrease in the film thickness. The gas atmosphere (air or nitrogen) during the films cooling to RT after deposition also influenced the electrical properties of films.

Effect of annealing conditions on structural and luminescencent properties of Eu3+-doped Gd2Ti2O7 thin films

Here we report on preparation of Eu3+-doped Gd2Ti2O7 pyrochlore luminescent thin films by pulsed laser deposition technique and their structural, morphological and optical characterization. The influence of annealing temperature and background gas (air vs. argon) on film photoluminescence is examined for the optimization of post-deposition annealing conditions. As-deposited amorphous films become pure pyrochlore crystalline after calcination at temperatures higher than 1000°C. Atomic force microscopy showed increase in the grain size from ∼20nm in the as-deposited to ∼60nm in the crystalline sample annealed at 1100°C. Scanning electron microscopy showed dense films with the uniform thickness of about 700nm. Luminescence spectra of crystalline films were complex and composed of better resolved emission lines than in the amorphous sample. Emission spectra showed that symmetry of Eu3+ sites become disturbed in annealed films due to the extrinsic thermal stress. Films treated in argon displayed similar emission and excitation spectral features like air-treated ones, but with better resolved emission lines. Calculated quantum efficiency of emission showed that optimization of annealing conditions led to an enhancement of films luminescence. The highest quantum efficiency of emission and the longest lifetime is found for the sample annealed at 1100°C in presence of argon.

Intermetallic Formation at Interface of Al/Cu Clad Fabricated by Hydrostatic Extrusion and Its Properties.

Al/Cu clad composed of Al core and Cu sheath has been produced by hydrostatic extrusion at 523 K, at an extrusion rate of 27. The prepared specimen was post-annealed at temperatures of 673 K and 773 K for various time durations, and the effect of annealing conditions have been analyzed. The hardness at the interface between Al and Cu matrix of the Al/Cu bimetal clad increases because of annealing. Results indicate that the hardness is more sensitive to annealing temperature than the annealing time. Three kinds of intermetallic compounds (IMC), namely, CuAl, Cu3Al2, and CuAl2, are formed at the Al-Cu interface, upon annealing at 673 K. On the other hand, four kinds of IMCs, namely, Cu4Al3, CuAl, Cu3Al2, CuAl2, are formed at the annealing temperature of 773 K. The growth of each IMC follows the parabolic law as a function of annealing times at certain annealing temperature. The growth rate of each IMC is limited to its interdiffusion rate constant. The IMC Cu4Al3 appears upon annealing at 773 K, and not during annealing at 673 K, because of the higher value of activation energy associated with its formation, when compared to other IMCs.

In situ investigation of the effect of stretching speed and annealing conditions on the crazing of as-spun IPP fibres using Pluta polarizing interference microscope

The effect of annealing conditions and stretching speed on the crazing and fracture behaviour of thermally treated as-spun IPP fibres during stretching with constant strain rate was investigated. The study includes observations and quantifying the crazing that occurs on stretched fibres via the estimation of the areal craze density as a function of annealing duration and stretching speed. An automated two-beam polarizing light interference Pluta microscope with the aid of modified mechanical stretching device are used for this investigation. Increasing the strain rate for thermally treated samples tends to delay the craze initiation and lowers the amount of areal craze density. A technique based on microscopic image analysis system(MIAS) with suitable designed software were used to observe the general feature of a single craze and calculate its wide and length. The value of strain rate is more effective than thermal history (annealing temperature and duration) on the crazing process of IPP fibres.

Effect of annealing and surfactant on photoluminescence of ZnS:O2− nanoparticles

Abstract ZnS:O2− (ZSO) nanoparticles were synthesized using a low temperature solid-state reaction method. The effects of annealing conditions and the content of the surfactant polyethylene glycol (PEG) on photoluminescence (PL) properties of the ZSO nanoparticles were studied. It was found that annealing and adding PEG during the synthesis did not change the crystal structure of ZSO nanoparticles, and their average crystallite size increased with increasing annealing time and temperature, but decreased with increasing PEG content. The emission intensity of ZSO nanoparticles was found to be enhanced after annealing or using PEG during the synthesis. Optimal annealing conditions both in air and vacuum and the optimal content of PEG were obtained for achieving maximum emission intensity from the ZSO nanoparticles.

Fabrication of microporous membranes from melt extruded polypropylene precursor films via stretching: Effect of annealing

In this work, the effects of annealing conditions on the microstructure of polypropylene (PP) precursor films and further on the porous structure and permeability of stretched membranes were investigated. Combinations of WAXD, FTIR, DSC and DMA results clearly showed the crystalline orientation and crystallinity of the precursor film increased with annealing temperature, while the molecular chain entanglements in the amorphous phase decreased. Changes in the deformation behavior suggested more lamellar separation occurred for the films annealed at higher temperatures. Surface morphologies of the membranes examined by SEM revealed more pore number and uniform porous structure as the annealing temperature increased. In accordance with the SEM results, the permeability of the membranes increased with annealing temperature. On the other hand, it was found that 10 min was almost enough for the annealing process to obtain the microporous membranes with an optimal permeability.

Effects of annealing conditions on crystallization of the CZTS absorber and photovoltaic properties of Cu(Zn,Sn)(S,Se)2 solar cells

Cu(Zn,Sn)S2 (CZTS) nanoparticles were synthesized by hot-injection method. Cu(Zn,Sn)(S,Se)2 (CZTSSe) solar cells were fabricated by printing method using CZTS nanocrystallites on molybdenum/glass substrate. The effects of annealing conditions such as temperature and ambient gas on microstructure and photovoltaic properties were investigated. CZTS films annealed in H2S ambient shows low crystallinity, being peeled off easily, and poor photovoltaic characteristics, namely, the parameters of the best cell are short-circuit current density (JSC) of 4.8mA/cm2, open-circuit voltage (VOC) of 0.59V, fill factor (FF) of 0.39, and conversion efficiency (η) of 1.12%. Meanwhile, CZTS films annealed under Se vapor shows high crystallinity and high cell performance: the parameters of the best cell are JSC=26.2mA/cm2, VOC=0.39, FF=0.48, and η=4.94%.

Effect of selenization conditions on the growth and properties of Cu2ZnSn(S,Se)4 thin films

The opto-electronic properties of copper zinc tin sulfide can be tuned to achieve better cell efficiencies by controlled incorporation of selenium. In this paper we report the growth of Cu2ZnSn(S,Se)4 (CZTSSe) using a hybrid process involving the sequential evaporation of Zn and sputtering of the sulfide precursors of Cu and Sn, followed by a selenization step. Two approaches for selenization were followed, one using a tubular furnace and the other using a rapid thermal processor. The effects of annealing conditions on the morphological and structural properties of the films were investigated. Scanning electron microscopy and energy dispersive spectroscopy were employed to investigate the morphology and composition of the films. Structural analyses were done using X-ray diffraction (XRD) and Raman spectroscopy. Structural analyses revealed the formation of CZTSSe. This study shows that regardless of the selenization method a temperature above 450 °C is required for conversion of precursors to a compact CZTSSe layer. XRD and Raman analysis suggests that the films selenized in the tubular furnace are selenium rich whereas the samples selenized in the rapid thermal processor have higher sulfur content.

Effect of Annealing Conditions on Microstructure of High Silicon Steel Prepared by Electrodeposition

The effect of annealing temperature and time on the microstructure, distribution of silicon,texture and magnetism of the high silicon steel prepared by electrodeposition was investigated. The results showed that after annealing at 1000℃ for 210 min, the mean grain size of steel was about 190 μm with a uniform grain size distribution, and the silicon is also uniformly distributed on the entire cross section with an average Si concentration 6.3715%(close to 6.5%); With the increasing annealing time at high temperature, the texture with double crystal planes {100} and {110} preferential oriented microstructure was enhanced, and the iron loss was lowered, implying a relatively good magnetism for the high silicon steel prepared by the proposed process.

Influence of Ge content and annealing conditions on the PL properties of nc-Si1−xGex embedded in SiO2 matrix in weak quantum confined regime

Fabrication of Si (nc-Si), Ge (nc-Ge), and Si1−xGex (nc-Si1−xGex) nanocrystals embedded in SiO2 matrix is achieved by thermal annealing of magnetron-sputtered thin films. Effects of annealing conditions, namely duration and temperature, as well as Ge content on the photoluminescence properties are investigated. Origin and evolution of the photoluminescence signal in the weak quantum confinement regime are discussed. It is found that photoluminescence signals can be decomposed into four Gaussian peaks originating from Ge-related radiative defects located at the sub-oxide (GeOx), either inside the matrix or at the interface region (peak M), nc-Si1−xGex/SiO2 interface-related localized states (peak I), localized states in the amorphous Si1−xGex bandgap (peak A) and quantum confinement of excitons in small nanocrystals (peak Q). The role of small and large nanocrystals in the photoluminescence mechanism is investigated by varying the mean nanocrystal size from 3nm to 23nm (from strong to weak quantum confined regime). Our results demonstrate that the quantum confinement effect in Ge nanocrystals manifests though spectral blueshift due to increase in Ge content. We also propose that the decreasing photoluminescence signal intensity with an increase in Ge content may originate from Ge-related nonradiative Pb centers.

Recrystallization behavior of a co-cast AA3xxx–AA6xxx aluminum alloy laminate — Effect of annealing conditions and cold reduction levels

The annealing behavior of a laminated AA3xxx–AA6xxx alloy system is investigated at temperatures and conditions which represent fine particle presence or dissolution in the AA6xxx (i.e. core) layer, as well as 60 or 80% cold reduction levels. The through-thickness microstructural characteristics of the cold rolled and annealed laminates are analyzed using various methods. It is found that the average grain size of the AA3xxx (i.e. clad) layer is generally finer than that of the core layer and the grains are more equiaxed in that layer for all conditions studied. The annealed microstructure of the core layer is also more strongly affected by the change in the annealing conditions. The dependencies of the average grain size and grain size aspect ratio on the annealing conditions are dictated by the presence, size, distribution and thermal stability of particles. A higher level of cold reduction results in reversing the trend of change in the grain size aspect ratios of both layers with annealing temperature in the range of 380 to 420°C (1h), while it yields characteristics similar to that obtained by 60% reduction when annealing is conducted for 30s at 540°C. These results are explained through the microstructural evolution parameters that are affected by cold rolling and annealing conditions.