Annealing Heating Rate Research Articles

Reducing the annealing heating rate sensitivity of Fe83.5Si3B10P2Cu1.5 soft magnetic nanocrystalline alloy by adjusting the melt spinning cooling rate

Reducing the annealing heating rate sensitivity of Fe83.5Si3B10P2Cu1.5 soft magnetic nanocrystalline alloy by adjusting the melt spinning cooling rate

Microstructure evolution and mechanical properties of bimodal grain sized 301 stainless steel strip induced by reverse phase transformation

The sub-micron bimodal grain structure of 301 austenitic stainless steel stripe obtained by phase reversion process, and the relationship between grain size distribution and mechanical properties was described in this study. With the change of annealing heating rate under the industrial condition 10 °C/min, the bimodal grain size of submicron scale was obtained at 750 °C. By analyzing the micrograph of bimodal structure, it was found that the deformed martensite transformed to austenite through diffusion transformation, and the recovery austenite grain had obvious size distribution. It was found that the bimodal structure was easier to form under the condition of slow heating rate, and the ultra-fine grain materials with high performance were obtained by controlling the annealing parameter. The high-density grain boundary of ultrafine grain presents microvoid in the tensile fracture, and the streaks formed by the aggregation of holes can be observed, which is considered to be caused by deformation twinning. The large dimples in the coarse grain are observed, as the strain-induced martensite was formed in the large grain of the bimodal structure.

Influence of Cold Rolled Deformation Degree and Heating Rates on Crystallite Dimension and Recrystallization Fraction of Aluminum Plates

In order to study the microstructure evolution rule of pure aluminum plates during different cold-rolled (CR) deformation degrees and annealing processes, samples with aCR deformation of 50~85%, heating rates of 60~100 °C/min and annealing at the target temperature of 350~500 °C were investigated. The microstructure, crystallite dimension and grain boundary characteristics were characterized by the methods of polarizing microscope (PM) and electron backscattered diffraction (EBSD). The results showed that the crystallite dimension of the initial state was 102 μm and ends up completely broken with an increase in the CR deformation degree. When the CR deformation increases to 85%, the deformed micro-bands were very small, with a band spacing of 5~10 μm. At this time, the grain distortion is more serious, there are more high-density grain defects, such as dislocations, and there is a high deformation of the storage energy, which is the energy preparation for the subsequent finished products to withstand the annealing process. The recrystallization fraction was higher with an increase in annealing temperature. After completed recrystallization, the grains showed an equiaxed shape. Orientation imaging and misorientation angle analysis showed that the red-oriented grains of the (001) plane, which had preferred nucleation, recrystallization and rapid grain growth. Final grains of the completed recrystallization are relatively coarse. Under the same deformation, the average crystallite dimension of the recrystallized grains decreases with an increase in annealing heating rate.

Effects of annealing processes on the crystallization and magnetic properties of nickel ferrite thin films

Magnetic nickel ferrite (NFO), NiFe2O4, thin films were fabricated using the chemical solution deposition method on (100)-oriented silicon substrates. The effects of an annealing process on the crystallization and magnetic properties of NFO thin films were investigated. Two annealing methods were used, namely layer-by-layer multiple rapid-annealing process and single slow-annealing process. The results showed that the appropriate pyrolysis temperatures range from 400 to 500°C. NFO thin films crystallized well when they were annealed at 750°C or above. The NFO thin films fabricated using the single slow-annealing process (NFO-S) show better crystallinity compared to the films fabricated using the layer-by-layer multiple rapid-annealing process (NFO-R) when the annealing temperatures were low. NFO-R thin films show preferred (400) orientation growth and the relative intensity of the (400) peak raises with the annealing heating rate. Fine magnetic hysteresis loops and good magnetic properties were observed in both NFO-S and NFO-R thin films. A saturation magnetization of 277 emu cm−3 was derived for the NFO-S thin films, compared to a 230 emu cm−3 for the NFO-R thin films, which is a very high value compared with former reported values for NFO thin films.

Annealing heating rate dependence of microstructure and multiferroic properties in Bi4Ti2.9Fe0.1O12/CoFe2O4 layered magnetoelectric composite films prepared by chemical solution deposition method

Lead-free magnetoelectric composite films of CoFe2O4 (CFO) and Bi4Ti2.9Fe0.1O12 (BTF) were prepared on the LaNiO3-coated Si substrate by chemical solution deposition. Though the CFO layer randomly grows on the LaNiO3 layer, the oriented growth of the BTF layer can be regulated by rapid annealing treatment. The results indicated that the annealing heating rate significantly affects the c-axis orientation of the BTF layer, thereby resulting in obvious changes in microstructure, leakage behavior, dielectricity and ferroelectricity of the BTF/CFO films. The BTF/CFO film prepared at the heating rate of 40 °C/s presents the most compact structure, minimum leakage current, maximum dielectric constant and the highest residual polarization of 28.8 μC/cm2. Moreover, the excellent magnetoelectric coupling performance along with the highest magnetoelectric coupling voltage coefficient αE of 20.1 V/cm∙Oe can be achieved in these conditions.

Enhanced Electrochromic Performance by Uniform Surface Morphology of Tungsten Oxide Films

Tungsten oxide(WO3) films with uniform surface morphology are fabricated using a spin-coating method for applications of electrochromic(EC) devices. To improve the EC performances of the WO3 films, we control the heating rate of the annealing process to 10, 5, and 1 oC/min. Compared to the other samples, the WO3 films fabricated at a heating rate of 5 oC/min shows superior EC performances for transmittance modulation(49.5 %), response speeds(8.3 s in a colored state and 11.2 s in a bleached state), and coloration efficiency(37.3 cm2/C). This performance improvement is mainly related to formation of a uniform surface morphology with increased particle size without any cracks by an optimized annealing heating rate, which improves the electrical conductivity and electrochemical activity of the WO3 films. Thus, the WO3 films with a uniform surface morphology prepared by the optimized annealing heating rate can be used as a potential candidate for performance improvement of the EC devices.

Strategic improvement of Cu2SnS3 thin film by different heating rates and photoluminescence investigation

Cu2SnS3 (CTS) thin films have been synthesized on molybdenum-coated soda lime glass substrates by sulfurization the Cu-Sn alloy precursors grown by radio-frequency magnetron sputtering technique. Strategic improvement has been carried out on the composition, structural, morphological and optical properties of CTS thin films sulfurized by rapid heating rate and slow heating rate. The annealing heating rate can adjust the ratio of Cu/Sn, improve the crystallinity and surface morphology. The ratio of Cu/Sn is close to the stoichiometric composition of CTS under slow heating rate with more loss of Sn. Structural characterization exhibits the CTS thin film sulfurized by slow heating rate has a better crystallinity without secondary phase. The CTS thin film obtained at slow heating rate presents a larger average grain size and smooth surface. The optical band gap of CTS thin films is at the vicinity of 0.87 eV. Photoluminescence (PL) spectroscopy has been used to study the carrier recombination mechanism and the electronic structure of CTS thin film by excitation power and temperature dependent measurements. The peak observed from PL spectra of CTS thin film conforms to the donor-acceptor pair recombination luminescence.

Growth of highly c-axis oriented LaNiO3 films with improved surface morphology on Si substrate using chemical solution deposition and rapid heat treatment process

LNO (LaNiO3) thin films were directly deposited onto Si substrates with a thin layer of amorphous natural oxide (SiO2) using three different precursor solutions. Effects of the constitution of precursor solution and the annealing heating rate on the surface morphology and the orientation were investigated. The LNO film derived from the mixture of a methanol solvent and an acetylacetone chelating agent had the flat surface with no cracks and pinholes. The heating rate of rapid annealing process had a critical effect on the oriented growth of the LNO film, and its c-axis orientation degree increased with the annealing heating rate. The LNO film with the heating rate of 40℃/s exhibited the highest degree of c-axis orientation (99.57%) and the lowest resistivity (9.35 × 10−4Ωcm). It would be a potential bottom electrode and/or seed layer to integrate perovskite-type films on it for functional devices.

Effects of the annealing heating rate on sputtered aluminum oxide films

Al x O y films by DC reactive magnetron sputtering were annealed in air ambient at 500 °C for 1 h with different heating rates of 5, 15, and 25 °C/min.Then heat treatments at 900 °Cwere carried out on these 500 °C-annealed films to simulate the high-temperature application environment. Effects of the annealing heating rate on structure and properties of both 500 °C-annealed and 900 °C-heated films were investigated systematically.It was found that distinct γ-Al2O3 crystallization was observed in the 900 °C-heated films only when the annealing heating rates are 15 and 25 °C/min. The 500 °C-annealed film possessed the most compact surface morphology in the case of 25 °C/min. The highest microhardness of both 500 °C-annealed and 900 °C-heated films were obtained when the annealing heating rate was 15 °C/min.

The Effect of Final Annealing Heating Rate on Abnormal Grain Growth in a Fe-3.5%Si Steel

In this study the effects of heating rate on the sharpness and size of Goss oriented ({110}<001>) grains during secondary recrystallization annealing at 900 °C was observed. The results show that, at the same annealing temperature, rapid heating of the samples to this temperature generates a higher drag force compared to a slower heating rate (5°C/min). The two groups of samples show different growth kinetics for Goss grains, in which at the longest annealing time, the rapid heating sample exhibits larger maximum Goss grain size compared to the slower heated samples.

Achieving Isolated Fe100−x Pt x Nanoparticles with High Magnetic Coercivity

Monodisperse Fe100−xPtx (x = 37, 41, 47, 54, 61, 66, 74) nanoparticles with an average size of 4.5 nm were successfully synthesized using the chemical polyol process. As-synthesized Fe100−xPtx nanoparticles have the chemi- cally disordered face-centered cubic (fcc) structure with A1 phase. To achieve an ordered structure L10 phase for FePt and L12 phase for FePt3 particles, high-temperature anneal- ing is required. In this work, with optimizing effective pa- rameters of annealing and also by changing the stoichiomet- ric of Fe100−xPtx nanoparticles, we were able to achieve co- ercivity of 16,500 Oe for Fe53Pt47, which is heat treated at 650 ◦ C for 60 min with 20 ◦ C/min (annealing heating rate). It is obvious that the annealing procedure in this tempera- ture leads to destruction of surfactant and sintering. In this work, chemically synthesized Fe53Pt47 nanoparticles were coated by a nonmagnetic CoO oxide shell to prevent them from sintering. Results show that the size of the core/shell (Fe53Pt47/CoO) nanoparticles after the annealing at a tem- perature of 650 ◦ C has not changed compared to the size of the as-synthesized state. Meanwhile, the coercivity of about 5580 Oe is obtained for this nanocomposite.

Influence of Annealing Heating Rate on Nb Ferritic Stainless Steel Microstructure and Texture

The cold rolled band of the niobium stabilized type ASTM 430 ferritic stainless steel with 85 % thickness reduction was annealed with heating rates of 0.10, 6.8, 23.5 and 41.5 °C/s and a soaking time of 24 s. The changes in microstructure and texture were followed by interruptions in the annealing cycle at temperatures of 780, 830 and 880 °C. Annealing at the lower heating rate was more effective for the development of γ-fiber than the annealing performed with high heating rate. The increased rate of heating provided an increase in the onset recrystallization temperature, a reduction in average grain diameter and a more homogeneous distribution throughout the thickness. The specimens with higher volume fraction of the γ-fiber annealed with low heating rate showed a high average coefficient of anisotropy R =1.99.

Texture generation and implications in TWIP steels

Recrystallization of an Fe–22Mn–0.6C TWIP steel occurs by site-saturated nucleation and causes a retained rolling texture, as opposed to some literature data, in which texture randomization is reported. The present results indicate that the annealing heating rate did not significantly influence the results. Randomization might be induced by a large hot-rolled grain size and annealing twins. TWIP steels appear to have higher r-values than typical Cube-dominated face-centred cubic metals, confirming their higher deep drawing potential.

Temperature dependence of oriented growth of Pb[Yb 1/2Nb 1/2]O 3–PbTiO 3 thin films deposited on LNO/Si substrates

(1 − x)Pb[Yb 1/2Nb 1/2]O 3– xPbTiO 3 (PYbN–PT, x = 0.5) (001) oriented thin films were deposited onto LaNiO3 (LNO)/Si (001) substrates by sol–gel processing. The crystallographic texture of the films was controlled by the annealing temperature and heating rate. Highly (001) oriented LNO thin films were prepared by a simple metal organic decomposition technique, and the samples were annealed at 700 °C and 750 °C using a rapid thermal annealing process and furnace, respectively. X-ray diffraction analysis revealed that the films of PYbN-PT were highly (001) oriented along LNO/Si substrates. The degree of PYbN-PT orientation is dependent on the heating rate and annealing temperature. Annealing heating rate of 10 °C/s and high annealing temperature near 750 °C produce the greatest degree of (001) orientation, which gives rise to improved dielectric properties.

Effect of Heating Rate on Recrystallization of Twin Roll Cast Aluminum

The effect of heating rate on precipitation and recrystallization behavior in twin roll cast (TRC) AA3105 has been investigated by three different means: conventional air furnace, controlled infrared, and lead bath heating. Experimental results showed that as-recrystallized grain size decreased and became more equiaxed as the annealing heating rate increased. These results were explained via time-temperature-transformation (TTT) curves for both dispersoid precipitation and recrystallization. With the faster heating rate, recrystallization could occur before precipitation of Mn present in the unhomogenized TRC samples. At a heating rate of 50 °C/s, the material underwent grain growth after recrystallization at 500 °C. No sign of grain growth was observed in materials annealed with lower heating rates, 3 °C/s, 0.5 °C/s, and 0.01 °C/s, due to greater dispersoid precipitation.

On the Influence of the Annealing Heating Rate on the Recrystallization Texture of a Deformed Single Crystal (110)[001] of 3% Silicon Iron

The reasons for changes in the type of the recrystallizatioin texture depending on particular annealing conditions of a deformed single crystal (110)[001] are discussed. It is shown that recrystallization centers (210)-(310)[001] can be formed at structural inhomogeneities of different type, such as transition bands, kink bands, and twin boundaries. The development of the texture component (210)-(310)[001] in deformed single crystals subject to slow heating is due mainly to the orientation dependence of the critical dimension of nuclei.