Increasing Heat Treatment Temperature Research Articles

Creep deformation behavior and microstructure of α-Mg/long-period stacking ordered (LPSO) duplex Mg-Y-Zn alloy prepared by hot extrusion and heat treatment

There exists a great demand for improving the creep resistance of α-Mg/long-period stacking ordered (LPSO) duplex alloys. In this study, microstructure control through hot extrusion and heat treatment was employed on Mg-Y-Zn duplex alloys with the aim of achieving superior creep resistance. The extruded Mg-Y-Zn alloy exhibited an enhancement in the creep resistance with increasing heat treatment temperature. Furthermore, the heat-treated samples demonstrated outstanding creep resistance even under high stress. Their creep behavior is characterized by a low minimum creep rate and a relatively small stress exponent (n ∼ 5) even at high stress. Microstructural observations revealed that heat treatment induces grain coarsening and an increase in solute concentration within the recrystallized grains. Additionally, during creep deformation, a plate-like LPSO phase and kink bands formed within the recrystallized grains. Therefore, it is affirmed that the exceptional creep resistance observed in the Mg-Y-Zn alloys in this study can be attributed to the microstructure evolution induced by heat treatment and creep deformation.

Warm Air Bending of AZ31B Sheets Based on an Online Local Contact Heating Method

Abstract Warm forming holds significant potential in shaping challenging materials due to its comprehensive advantages compared to cold and hot forming. Effective heating is crucial for precise warm forming processes. This study explored an innovative warm air bending technique employing an online local contact heating method. Heat transfer during the preheating stage and the air bending of AZ31B sheets were investigated through experiments and finite element analysis at temperatures ranging from room temperature (24 °C) to 250 °C, considering the thermomechanical coupling effect. The results indicate a significant increase in the bending center angle, advancing from 69.8 deg to more than 119 deg as the heating temperature rises from room temperature to 250 °C. Fractures were effectively eliminated when the sheet heating temperatures exceeded 150 °C. Simultaneously, as the localized heating temperature increases, a corresponding decrease in the rebound angle is observed, reducing from 10.6 deg to 2.3 deg. The findings validate the feasibility of warm air bending using online local contact heating in industrial applications, with regard to forming quality and production efficiency.

Effect of heat treatment on the radial structure of coaxial polyacrylonitrile/mesophase pitch composite fiber

AbstractCoaxial composite fibers with a cortex of polyacrylonitrile (PAN) and a core layer of mesophase pitch (MP) and PAN were prepared by wet spinning, then heat‐treated in air. The effects of heat treatment on the thermal reaction characteristics, pre‐oxidation degree, radial structure, and thermal stability of coaxial composite fibers were studied by differential scanning calorometry, Raman, and thermogravimetric analysis. As the heat treatment temperature increases, the coaxial composite fibers only undergo cyclization without oxidation, the peak temperature of the thermal reaction increases from 258 to 270°C, and the enthalpy increases from 19.66 to 237.82 J g−1, the heat mainly arises from the PAN component. The Dr value of the coaxial fiber skin layer increases from 0.193 to 0.255 (330°C) and then decreases to 0.236; the core layer Dr value increases from 0.353 to 0.392 (310°C) and then decreases to 0.368. The pre‐oxidation reaction leads to an increase in sp2‐hybridized carbons and an increase in pre‐oxidation degree. When the heat treatment temperature <310°C, the pre‐oxidation degree of the composite fibers increases, leading to formation of a more stable structure compared with that at lower temperatures and an increase in the carbon residue rate.

Simulation and Experimental Study of Circulatory Flash Evaporation System for High-Salt Wastewater Treatment

Treatment methods for high-salt wastewater mainly consist of physical methods, chemical methods and biological methods. However, there are some problems, such as slow treatment speed, high investment costs and low treatment efficiency. To address NaCl solutions, in this study, a circulatory flash system was designed based on gas–liquid equilibrium, mass conservation equation and energy conservation equation. A circulatory flash evaporation simulation and a static flash evaporation experiment were conducted on NaCl solutions under various operating conditions to investigate the effects of heating temperature, flash pressure and initial NaCl concentration on the circulatory flash evaporation system. The significance of each factor’s influence on the evaporation fraction and energy consumption was examined through static flash experiments. The simulation results demonstrated that increasing the heating temperature, decreasing the flash pressure and having a higher initial NaCl concentration could enhance the treatment capacity of high-salt wastewater. The flow rate of vapor outlets increased with higher heating temperature but decreased as the flash pressure rose. The experimental results demonstrated that flash evaporation pressure was the primary factor influencing both the evaporation fraction and the energy consumption per unit mass of vapor produced. It was observed that with an increase in heating temperature, the flash pressure decreased and there was a corresponding decrease in energy consumption per unit mass of vapor produced. The optimal experimental conditions were achieved at a heating temperature of 99 °C, a flash pressure of 15 kPa, and an initial NaCl concentration of 20%.

Effect of heat treatment on interface failure behavior in SiCf/PyC/SiC composites reinforced with Cansas-3 fibers

The influence of heat treatment on the correlation between interfacial mechanical properties and microstructure in CVI-SiCf/PyC/SiC composites was systematically investigated. The results reveal a progressive reduction in the average interfacial bond strength, interfacial shear stress, and interfacial debonding energy within the composites as the heat treatment temperature increases, especially beyond 1350 °C. This decline can be attributed to the attenuation of the SiCf/PyC interfacial bond strength arising from the contraction in fiber volume induced by the precipitation of Cansas-3 fibers. After push-in testing, SiCf/PyC/SiC composites heat-treated at or below 1350 °C displayed fibers in a compressed state. Conversely, composites exposed to extended heat treatment at 1400 °C or higher maintained fibers in an ejected state after push-in testing. Moreover, the composites heat-treated at 1450 °C and 1500 °C demonstrated fibers that were spontaneously ejected subsequent to cross-section polishing.

Uniaxial compressive stress-strain model of Molybdenum tailings concrete after high-temperature exposure

To investigate the effect of high-temperature exposure on the mechanical properties of molybdenum tailings concrete, 75 cubes and 150 prisms of molybdenum tailings concrete were tested, by considering five heating temperatures (20, 200, 400, 600, and 800 ℃) and five replacement ratios (0, 25, 50, 75, 100%). The failure modes, mass loss rate, and mechanical properties of the specimens were analyzed in detail. The experimental results indicate that with an increasing heating temperature, the color of the blocks became lighter, accompanied by gradually intensifying phenomena such as skin peeling and crack propagation. At 800 ℃, many small cracks at the fracture site of the blocks after splitting failure, and obvious fracture zones in the block under axial compression failure were observed. With an increasing temperature, the mass loss rate and peak strain of the molybdenum tailings concrete show a linear growth trend, reaching the maximum amplitude at 800 ℃ (7.85% and 192.5%), whilst the molybdenum tailings concrete splitting tensile strength, peak stress, and elastic modulus showed a decreasing trend, reaching the maximum amplitude (404%, 61.7%, and 84.9%). By increasing replacement ratios, the mass loss rate of the molybdenum tailings concrete shows a linear growth trend, with a maximum increase of 1.07%. The mechanical properties of the concrete at all temperatures show a trend of first increasing and then decreasing. A 25% replacement ratio can improve the deterioration of the molybdenum tailings concrete after high-temperature exposure, with the maximum amplitude increase of the peak stress, peak strain, and elastic modulus being 24.3%, 12.4%, and 21%, respectively. Based on the test data, the prediction formulas of the mechanical properties of molybdenum tailings under different high-temperature and molybdenum tailings replacement ratios are fitted. The existing constitutive equations are modified to establish the stress-strain constitutive model of molybdenum tailings concrete after high-temperature exposure, of which results are in good agreement with the test data.

Encapsulation of roast beef flavor by soy protein isolate/chitosan complex Pickering emulsions to improve its releasing properties during the processing of plant-based meat analogues

During the production of plant-based meat analogues (PBMA), a significant loss of flavor characteristic compounds in meat-flavor essences could be observed. Pickering emulsion-based encapsulation is an effective method to improve their stability. Therefore, a soy protein isolate (SPI)/chitosan (CS) complex Pickering emulsion was fabricated to encapsulate roast beef flavor (RBF) and further applied in the processing of PBMA. Our results indicated that the network structure of emulsions was dominated by elasticity, while hydrogen and covalent bonding interactions played important roles in the encapsulation process. The release rate of flavor compounds gradually increased with the increase of pH value, glutamine transaminase, NaCl content, heating temperature or heating time, while encapsulation significantly reduced the loss of characteristic aroma compounds. In addition, the releasing characteristics of aroma compounds and textural properties of PBMA were greatly improved by treating with RBF-loaded emulsions. Consequently, the emulsions were promising to improve the flavor quality of PBMA.

Phase transformation sequence of amorphous nickel-molybdenum electrodeposit

In this paper, the amorphous Ni-Mo alloy with cauliflower-like morphology is successfully prepared by electrodeposition, and the effects of heat treatment on its morphology, element content and structure are studied. The results of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) show that, when the temperature is higher than 600 ℃, the fine grains gradually appear and then cover the entire surface of Ni-Mo alloy. The Ni-Mo alloy occurs simultaneously the segregation phenomenon and the Mo content increases on the surface. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis illustrate that the Ni-Mo alloy gradually transfers from amorphous into crystalline structure, and the first phase MoNi4 and the second phase MoNi precipitate near 633℃ and 707℃ respectively. The apparent activation energy is 234.1 kJ/mol (ΔEa1) for the first phase crystallization and 819.9 kJ/mol (ΔEa2) for the second phase crystallization. The HER catalytic activity of Ni-Mo alloy increases first and then decreases with the increase of heat treatment temperature.

Non-stoichiometric silicon nitride for future gravitational wave detectors

Silicon nitride thin films were deposited at room temperature employing a custom ion beam deposition (IBD) system. The stoichiometry of these films was tuned by controlling the nitrogen gas flow through the ion source and a process gas ring. A correlation is established between the process parameters, such as ion beam voltage and ion current, and the optical and mechanical properties of the films based on post-deposition heat treatment. The results show that with increasing heat treatment temperature, the mechanical loss of these materials as well as their optical absorption decreases producing films with an extinction coefficient as low as k=6.2(±0.5)×10−7 at 1064 nm for samples annealed at 900 ∘C. This presents the lowest value for IBD SiN x within the context of gravitational wave detector applications. The mechanical loss of the films was measured to be ϕ=2.1(±0.6)×10−4 once annealed post deposition to 900 ∘C.

Effects of shell mold heating temperature on microstructures and freckle formation of single crystal superalloys

To study the effects of shell mold heating temperature on the microstructure and freckle formation of single crystal superalloys, the directional solidification experiment and simulation were conducted with designed stepwise specimens. The temperature field and morphology of mushy zone were analyzed. The results show that the primary and secondary dendrite arm spacings both decrease with the rise of shell mold heating temperature. This reduces the permeability of the liquid in the mushy zone and the width of the thermal-solutal convection channel, which reduces the formation tendency of freckles, the width of freckles and the number of dendritic fragments in freckled areas. In addition, with the increase of shell mold heating temperature, the cooling rate of liquid in the mushy zone increases, which reduces the cooling time of the melt in the mushy zone, weakens the breaking capability of liquid flow to the dendrite, and further reduces the tendency of freckle formation in single crystal superalloy castings.

The effect of time and heat exposure on the wettability and glossiness of CAA and FPL coatings for aluminum substrates

The use of anodized coatings as a substrate for adhesive bonding of aluminum is widespread and generally accepted. However, with time and exposure to heat, the coating’s behavior changes and its wettability decrease. We examine the coating’s wettability by measuring the contact angle. Aluminum sheets are coated with two types of anodizing and FPL coatings for this study. The results indicate that the wettability of all coatings remains stable for 16 h post application. However, there is a significant decrease in wettability over extended time periods, with the anodized coating exhibiting more pronounced changes after 30 days compared to the FPL coating. Also, in both types of coatings, as the heating temperature increases, the wettability decreases and the contact angle increases. The changes in the anodized coatings are more pronounced than in FPL coatings. Measuring the glossiness of the coating before and after heating shows that the gloss and the surface roughness of the coating remain unchanged.

CALPHAD simulation and experimental study on heat treatment process of Al-Cu-Mn-Mg-Sc cast alloys

Because different heat treatment parameters have different effects on the microstructure and mechanical properties, it is necessary to optimize the heat treatment parameters to obtain alloys with better properties. In this study, the heat treatment parameters of Al-Cu-Mn-Mg-Sc cast alloys were optimized by using thermal simulation and experimental methods. The results show that the phase transformation temperature of the low melting point eutectic phase Al2Cu is 542.9 ℃, and the time for element homogenization distribution of the alloy during solid solution at 525 ℃, 535 ℃ and 550 ℃ is 8 h, 7 h and 4.5 h, respectively. With the rise of solid solution temperature, the microhardness increase at first and then decrease, and the microhardness reaches to 96.4 HV at 535 ℃. When solid solution heat treatment is carried out at 535 ℃ for different times, the microhardness increase at first and then decrease with time, and the microhardness reaches to 118.4 HV at 5 h. It is known that the number of metastable phase decreases gradually with the increase of aging heat treatment temperature by using the calculation of thermodynamic software. The optimal aging heat treatment process parameter for the alloy is 170 ℃ for 10 h, and the microhardness at this time reaches to 142.3 HV.

Enhanced dynamic-mechanical property and microstructural mechanism of a FeCoNiCrMo0.2 high-entropy alloy fabricated using powder bed fusion

Powder bed fusion (PBF), along with subsequent heat treatment, plays a crucial role in enhancing the impact toughness of FeCoNiCrMo0.2 high-entropy alloys (HEAs) and expanding their potential applications in field for high-speed deformation. In this study, the dynamic-mechanical properties and microstructure of the as-built PBF–FeCoNiCrMo0.2 HEAs and quenched PBF–FeCoNiCrMo0.2 HEAs heated at 600–750 °C for 8 h were investigated. As the heating temperature increases, the columnar grains and cellular structures undergo coarsening and the dislocation density gradually decreases. Moreover, higher heating temperatures facilitate the precipitation of Mo-rich second phases. This occurrence can be primarily attributed to the segregation of Mo at the boundaries of the as-built specimens. Consequently, in the quenched specimens, the μ phases are predominantly distributed along the boundaries of the cellular structures. In the quenched Q700 specimen (heated at 700 °C for 8h), the size and volume fraction of the μ phases are measured to be 63.4 nm and 3.59%, respectively. Additionally, under the same condition, the Q700 specimens also exhibited a relatively slight increase in the size of the cellular structures. The impact energy absorption, dynamic yield strength, and dynamic compressive strength of the Q700 quenched specimens were found to be 210.1 MJ/m3, 1066 MPa, and 1649 MPa at a strain rate of 1840 s−1. These values represent a dramatic improvement of 38.1%, 52.7%, and 14.7% higher in comparison to those of the as-built specimens. Under impact deformation, the presence of the μ phases plays a significant role in impeding the movement of dislocations by acting as a pinning agent for the boundaries of the cellular structures, thereby enhancing the strength. Simultaneously, the cellular structures were significantly elongated to form the deformation bands and to coordinate the impact deformation, leading to good impact energy absorption. In combination, the synergistic strengthening and toughening effect of the μ phases and the elongated cellular structures contribute to a remarkable improvement in the impact toughness of the PBF-HEAs.

Preparation and study on combustion performance of AP@ZrH2 core-shell composite energetic materials with high volume energy density

The development of composite energetic material with high volume energy density could increase the range and loading capacity of solid propellants. In this study, a series of core-shell composite energetic materials AP@ZrH2 were fabricated by decorating ZrH2 on the ammonium perchlorate (AP) through a solvent-nonsolvent method. A substantial increase in combustion heat (13373.67 J/g) and maximum burning temperature (1415.33 °C) are detected in composites in contrast to physically mixed sample (10660.46 J/g and 837.22 °C). This is due to the enhancement of the decomposition performance of AP, which provides sufficient oxidation gas atmosphere for combustion of ZrH2. In addition, the delay time (524 ms) and burning time (114 ms) of composites are significantly decreased compared to the physical mixed sample (2145 and 256 ms). The remarkable combustion performance and burning rate could be attributed to reduced mass and heat transfer distances. Finally, the improvement of combustion efficiency in the composites makes the size of the residual particles smaller.

Analysis of the ceramic coatings' recrystallization produced on the surface of the Zr-25Ta-25Ti alloy

The objective of this study is to analyze the influence of the heat treatment temperature carried out at ultra-high vacuum on surfaces formed in the Zr-25Ta-25Ti alloy by the micro-arc oxidation (MAO) technique to produce a ceramic layer with high hardness and high wear resistance. The results of structural (XRD) and microstructural characterization (SEM, optical and confocal microscopy technique) show that the surfaces are mainly composed of zirconium dioxide (ZrO2), Ti2ZrO, and calcium oxide (CaO). The heat treatments at high temperatures (500–800 °C) altered the phases of the MAO coating, forming ZrC. Confocal images showed that increasing temperature increased the roughness of the coatings (0.65 → 1.06 μm). Consequently, the topography of the coatings, wettability, microhardness (Vickers), and wear resistance (obtained by the ball cratering technique) of the materials are also modified. The wear results show that the MAO coating has a low wear rate value due to the MAO surfaces’ high hardness, efficiently protecting the substrates of the Zr-25Ta-25Ti alloy against tribological phenomena. Finally, the increase in heat treatment temperature promoted the formation of cracks in the coatings due to the difference in thermal expansion of the MAO ceramic with the Zr-25Ta-25Ti alloy substrate, causing a decrease in the hardness value and reducing wear resistance.

Effect of heat treatments on mechanical properties and wear resistance of laser-powder bed-fused Ti6Al4V alloy

The effects of heat treatment on the microstructure, mechanical properties and wear resistance of Selective Laser Melting Ti6Al4V alloy were systematically studied. The results show that the as-built part has an acicular [Formula: see text] martensite structure. The increase in heat treatment temperature causes the decomposition of acicular [Formula: see text] martensite, which leads to the decrease of the hardness of Ti6Al4V alloy. When the heat treatment temperature is 800∘C, the alloy forms an [Formula: see text]/[Formula: see text] structure, which increases the tensile strength and elongation of the alloy by 12% and 23%, respectively. When the heat treatment reaches above 900∘C, the mechanical properties of the alloy decrease sharply due to the disappearance of the [Formula: see text]/[Formula: see text] structure, the coarse grains of the [Formula: see text] phase, and the increase of the content of the [Formula: see text] phase. The tensile strength decreased from 935[Formula: see text]MPa to 815[Formula: see text]MPa, and the elongation decreased from 8.7% to 3.1%. With the increase of heat treatment temperature, the friction coefficient and wear rate increase linearly, which is opposite to the changing trend of hardness, and the wear mechanism is changed from single abrasive wear to abrasive wear and oxidative wear. This is attributed to the increase in the grain size of the alloy and the increase in the content of the [Formula: see text] phase, resulting in a decrease in the overall hardness of the alloy.

Fracture behavior and fracture surface roughness of high-temperature granite subjected to liquid nitrogen and water cooling

The thermal damage mechanism of water and liquid nitrogen on granite is a key scientific concern in reservoir fracturing. This study conducted fracture tests on high-temperature granite specimens subjected to water and liquid nitrogen cooling. The fracturing process was monitored and the fracture surface roughness was evaluated. The results indicated that the P-wave velocity, peak load, and fracture toughness exhibited a decreasing trend with increasing heating temperature. Specifically, at 150 °C, liquid nitrogen cooling samples exhibited higher fracture toughness than untreated ones. Acoustic emission events at peak load were more prominent in liquid nitrogen cooling samples, indicating higher brittleness and concentrated energy release. Conversely, water cooling samples displayed prolonged post-peak stages, suggesting greater ductility. The size of fracture process zones (FPZ) generally increased with temperature, with water cooling samples consistently exhibiting larger FPZ dimensions compared to liquid nitrogen cooling samples. Despite this, liquid nitrogen cooling resulted in significantly rougher fracture surfaces and numerous small cracks, while water cooling formed more extended through-going fractures. This suggests that high-temperature granite reservoirs by liquid nitrogen fracturing can enhance heat exchange areas more effectively. Additionally, different types of granite exhibit varying responses to temperature changes and cooling treatments, contingent on their unique mineral composition and structure.

Direct artificial aging of the PBF-LB AlSi10Mg alloy designed to enhance the trade-off between strength and residual stress relief

The AlSi10Mg alloy is one of the most studied alloys processed by the Powder Bed Fusion-Laser Beam (PBF-LB). Many already published works focus on post-process heat treatments to reduce residual stress or improve mechanical strength. Instead, the present study aims to identify direct artificial aging (AA) heat treatment able to optimize both aspects, thus enhancing the trade-off between strengthening and residual stress relief for the PBF-LB AlSi10Mg alloy produced using a no-heated platform. Higher temperatures (190–240 °C) than those typically used in AA heat treatment were selected based on thermal analysis to benefit both residual stress relief and precipitation of reinforcing phases from the supersaturated solid solution of the metastable as-built alloy. The effects of AA heat treatment on mechanical properties (i.e. hardness) and residual stress were evaluated by plotting aging curves and by XRD and Raman analyses and demonstrated that different trade-offs between strengthening and stress relief can be achieved by tuning heat treatment parameters (temperature and time). In particular, the exposure at the lowest temperature (190 °C) induced a partial decrease in residual stress and a slight increase in hardness. By increasing heat treatment temperature and soaking time, the relief was more significant, whilst the decrease in hardness was rather limited. The results are supported by the microstructural changes observed on the samples due to the different heat treatment conditions applied and show the feasibility of designing an AA heat treatment for the PBF-LB AlSi10Mg alloy capable of satisfying the mechanical response required by the final application.

Preparation and characterization of novel lightweight Y2Si2O7 fibrous porous ceramics for high temperature thermal insulation

Fibrous porous ceramics play a vital role in the field of thermal protection systems. In this work, novel lightweight Y2Si2O7 fibrous porous ceramics were successfully prepared based on Y2Si2O7 fibrous membranes by molding method. The effects of mechanical dispersion speed and heat treatment temperature on the properties of Y2Si2O7 fibrous porous ceramics were characterized. The results revealed that benefiting from the appropriate fiber length, the ceramics had a better performance at a mechanical dispersion speed of 4000 revolutions per minute. The density, shrinkage, and compressive strength of the ceramics increased, but the porosity decreased slightly with the increasing heat treatment temperature. The prepared Y2Si2O7 fibrous porous ceramics exhibited favorable properties like low density (0.37 g/cm3), high porosity (90.56%), good high-temperature resistance (∼1350 °C), and low thermal conductivity (∼0.12 W m−1 K−1 at 27 °C, ∼0.566 W m−1 K−1 at 1000 °C). These properties indicate that Y2Si2O7 fibrous porous ceramics could be a promising candidate as thermal insulation materials in high-temperature environments.

Effects of the combination of phenolic-resin impregnation and heat treatment on physical, mechanical and decay resistance of Taxodium hybrid “Zhongshanshan” wood

ABSTRACT This study aimed to evaluate the influence of cooperative modification treatments and treatment sequencing on the properties of treated fast-growing wood. Two integrated treatment methods including, impregnation with Phenol-Formaldehyde resin followed by heat treatment (PF-HT), and heat treatment antecedent to impregnation with Phenol-Formaldehyde resin (HT-PF) were applied on Taxodium hybrid “Zhongshanshan” wood. Comprehensive characterization was undertaken, investigating micro-morphology, chemical structure, mechanical properties, shrinkage and expansion properties, and decay resistance before and after treatment. Results indicated that the weight percentage gain (WPG) of the HT-PF wood exceeded that of the PF-HT wood, and the WPG of the former displayed an ascending tendency with increasing heating temperature, reaching a final difference of 10%. For instance, the modulus of elasticity of the HT-PF wood was 18% higher than that of the PF-HT wood in the bending test at a temperature of 215°C. Throughout the dynamic water adsorption test, both the hydrated water percentage and the dissolved water percentage of PF-HT wood were lower than those of PF-HT wood. After 3 months of exposure to brown-rot fungi, both HT-PF wood and PF-HT wood achieved a high level of decay resistance.