Transformation Temperature Research Articles

Microstructure Evolution of Cold-Rolled Carbide-Free Bainite Steel Sheets During Continuous Annealing Process

A modified carbide-free bainite (CFB) steel has been developed, building on existing alloys for compatibility with commercial continuous annealing lines (CALs), featuring a low austenitization temperature and short overaging time. The microstructural features of such candidate CFB sheets are compared with those of conventional CFB steel sheets that require higher reheating temperatures and longer overaging times. The effects of annealing parameters such as reheating temperatures and overaging temperatures on phase transformation kinetics and microstructure evolution are presented. The annealing process was simulated in a Gleeble thermomechanical processing simulator, and the microstructural characterization was carried out using XRD, SEM, and EBSD. Reconstruction of parent austenite grains from EBSD data did not reveal any variant selection, regardless of changes in the austenitization temperature, overaging temperature, or carbon content. It was observed that the V1–V2 variant pairing is the most common at the lower overaging temperature for reheating at 950 °C; however, this pairing decreases as the isothermal overaging temperature increases, with variant pairings involving low misorientation boundaries—such as V1–V4 and V1–V8—becoming more frequent. Steels with higher carbon content exhibit no significant changes in their variant pairing, regardless of variations in the austenitizing or isothermal temperatures. The XRD results show that the retained austenite fraction is reduced by increasing the isothermal transformation temperature.

Research on Transformer Temperature Early Warning Method Based on Adaptive Sliding Window and Stacking

Research on Transformer Temperature Early Warning Method Based on Adaptive Sliding Window and Stacking

Role of local structural distortions in the variation of martensitic transformation temperature with e/a ratio in Ni2Mn1+xZ1-x (Z = In, Sn or Sb) alloys.

Ni2Mn1+xZ1-x (Z = In, Sn or Sb) undergo martensitic transformation with transformation temperature (TM) scaling with the average valence electron per atom (e/a) ratio. However, the rate of increase of TM depends on the type of Z atom, with the slope of TMvs. e/a curve increasing from Z = In to Z = Sb. Local structural distortions are believed to be the leading cause of martensitic transformation in these alloys. A careful study of the Ni and Mn local structures in several Ni2Mn1+xZ1-x alloys with varying e/a ratio and the same Z atom, with the same e/a ratio but different Z atoms and with the same TM but with different Z atoms and different e/a ratio, revealed that the difference between Ni-Mn and Ni-Z nearest neighbor distances decreases as the Z atom changes from In to Sb. This decrease in the local structural distortion accommodates a higher content of Mn until the L21 structure becomes unstable and the alloy undergoes a martensitic transformation.

Laser induced oxidation Raman spectroscopy as an analysis tool for iridium-based oxygen evolution catalysts.

The study of degradation behavior of electrocatalysts in an industrial context calls for rapid and efficient analysis methods. Optical methods like Raman spectroscopy fulfil these requirements and are thus predestined for this purpose. However, the iridium utilized in proton exchange membrane electrolysis (PEMEL) is Raman inactive in its metallic state. This work demonstrates the high oxidation sensitivity of iridium and its utilization in analysis of catalyst materials. Laser induced oxidation Raman spectroscopy (LIORS) is established as a novel method for qualitative, chemical and structural analysis of iridium catalysts. Differences in particle sizes of iridium powders drastically change oxidation sensitivity. Oxidation of the iridium powders to IrO2 occurred at a laser power density of 0.47 ± 0.06 mW μm-2 for the 850 μm powder and at 0.12 ± 0.06 mW μm-2 and 0.019 ± 0.015 mW μm-2 for the 50 μm and 0.7-0.9 μm powders respectively. LIORS was utilized to assess possible deterioration of an iridium electrocatalyst due to operation under electrolysis. The operating electrocatalyst exhibited higher oxidation sensitivity, suggesting smaller iridium particle size due to catalyst dissolution. Peak shifts of the IrO2 signal were utilized to assess differences in transformation temperatures. The operated electrocatalyst transformed to IrO2 at lower temperature (8 cm-1 redshift) relative to the pristine catalyst (10 cm-1 redshift), demonstrating that pre-oxidation of the iridium to amorphous IrOx during electrolysis diminishes the energy barrier needed for IrO2 formation. Thus, LIORS can be utilized as a straightforward screening method for the analysis of iridium electrocatalysts in the industrial application of PEMEL.

EFFECT OF ORIGINAL STRUCTURE ON AGING-INDUCED MICROSTRUCTURE AND TRANSFORMATION BEHAVIOR OF Ni-RICH NITI ALLOY USING VARIOUS AGING MODEs

In the present study we discuss the evolution of aging-induced microstructure, critical temperatures of martensitic transformations (MTs) and their specific temperature ranges, latent heat and thermal hysteresis in Ni50.8Ti alloy with various original structures (OS) obtained using three different processing (including cold rolling/drawing, hot shear rolling and subsequent various solution treatment): fine-grained recrystallized structure (OS_1); hot deformation-induced structure (OS_2); coarse-grained recrystallized structure (OS_3). Subsequent aging was performed in a temperature range of 300−500 °C for 1−20h. After aging, OS_1 ensures two-stage MTs A→R and R→M upon cooling regardless of aging mode; OS_2 provides evolution from one-stage MT A→R to triple-stage MT at latest stage of aging; the quadruple-stage MT is revealed in OS_3 after aging at 430°C. Low-temperature aging at 300 °C ensures the most effective stabilization of R-martensite regardless of an original structure; high-temperature aging at 500 °C provides the least effective stabilization of R-martensite. Specific features of evolution of the latent heat and the width of hysteresis vs aging modes was explained by microstructural evolution. The correlation between values in the latent heats upon cooling/heating and hysteresis vs the aging duration were revealed. Hysteresis of an original structure is inherited after subsequent aging. The combined effect of an original structure and aging mode on the above characteristics is very complex and depends on a lot of competing factors; they are analyzed in detail. The revealed regularities permit precise tuning of the studied characteristics in a wide range to ensure the most favorable their combination for practical use.

Tuning structural transformations in MnCoGe System: The role of Vanadium-induced d-d hybridization

The impact of introducing the 3d transition metal vanadium (V) into the Ge site of the MnCoGe system has been investigated both theoretically and experimentally. Calculations reveal that V alters local bonding characteristics and reduces the structural transformation temperature when its concentration on the Ge site is below 25%. However, higher V content induces phase instability, making it challenging to form a single-phase MnCo(Ge, V) alloy. To address this, a combination of melt spinning and post-annealing was employed, successfully extending the V content to 10% on the Ge site. This process resulted in a complete Curie temperature window with a width of approximately 100K, and the annealed ribbons exhibited a relative cooling capacity 46% higher than that of the ingot samples. This study demonstrates a strategy for stabilizing structure and achieving magnetostructural coupling by introducing d-d hybridization to partially replace p-d hybridization, offering a pathway for developing new MM’X-based materials.

The effect of air-cooling heat treatment on the microstructure and phase transformations of structural steels

The aim of this study was to investigate the microstructure, phase transformations, and hardness changes of S235JR, S275JR, and S355JR structural steels after air-cooled heat treatment. The steel samples were austenitized at 1000°C and then cooled in air, and the sample temperatures were recorded with a thermocouple during cooling. The microstructure and phase transformations of the samples were analyzed both experimentally and with the Computerized Combining Phase Diagrams and Thermochemistry (CALPHAD) material property software. It was observed that higher carbon and manganese levels in structural steels lower the phase transformation temperatures, promote bainite formation, reduce the average ferrite grain size, and consequently lead to an increase in hardness. The phase ratios and hardness values were determined by the predicted experimental results with a deviation of less than 3%. These results show that a balanced ferrite and bainite phase distribution is achieved air cooling and the software effectively models these transformations.

On Transformation and Stress–Strain–Temperature Behavior of Fine-Grained Ni-Rich NiTi Wire vs. Aging Mode

The present study was carried out using a cold-drawn wire of Ni50.8Ti at.% subjected to post-deformation solution treatment at 700 °C for 1 h to obtain a fine-grained recrystallized structure. Subsequent aging was carried out at a temperature range of 300, 430, and 500 °C for 1, 10, and 20 h. The time–temperature aging mode strongly affects the aging-induced microstructure. Variation of the aging-induced microstructure (using various aging modes) permits precise tuning of the characteristic temperature of the martensitic transformations and their specific temperature ranges upon cooling and heating. The latent heat and hysteresis exhibit different evolution vs. aging durations; this finding remains fair when using different aging temperatures. The aging mode strongly affects the stress–temperature behavior: (i) a dramatical expansion of the temperature range of realization of the transformation yield stress (σtr); and (ii) the magnitude of σtr at a chosen test temperature is generally determined by the position of the Ms temperature. An additional contribution of competing factors is discussed. The efficiency of the aging temperature under isochronous aging is significantly higher than the efficiency of the aging time under isothermal aging. Aging at 430 °C for 10–20 h provides the highest resource for the recovery strain. The strain–temperature behavior strongly depends on the relative position of the Rs and Ms temperatures (onset of B2→R and R→B19′ transformations, respectively). The regularities obtained can be used to predict the set of functional and mechanical properties of titanium nickelide.

Design and Optimization of W-Mo-V High-Speed Steel Roll Material and Its Heat-Treatment-Process Parameters Based on Numerical Simulation

W-Mo-V high-speed steel (HSS) is a high-alloy high-carbon steel with a high content of carbon, tungsten, chromium, molybdenum, and vanadium components. This type of high-speed steel has excellent red hardness, wear resistance, and corrosion resistance. In this study, the alloying element ratios were adjusted based on commercial HSS powders. The resulting chemical composition (wt.%) is C 1.9%, W 5.5%, Mo 5.0%, V 5.5%, Cr 4.5%, Si 0.7%, Mn 0.55%, Nb 0.5%, B 0.2%, N 0.06%, and the rest is Fe. This design is distinguished by the inclusion of a high content of molybdenum, vanadium, and trace boron in high-speed steel. When compared to traditional tungsten-based high-speed steel rolls, the addition of these three types of elements effectively improves the wear resistance and red hardness of high-speed steel, thereby increasing the service life of high-speed steel mill-roll covers. JMatPro (version 7.0) simulation software was used to create the composition of W-Mo-V HSS. The phase composition diagrams at various temperatures were examined, as well as the contents of distinct phases within the organization at various temperatures. The influence of austenite content on the martensitic transformation temperature at different temperatures was estimated. The heat treatment parameters for W-Mo-V HSS were optimized. By studying the phase equilibrium of W-Mo-V high-speed steel at different temperatures and drawing CCT diagrams, the starting temperature for the transformation of pearlite to austenite (Ac1 = 796.91 °C) and the ending temperature for the complete dissolution of secondary carbides into austenite (Accm = 819.49 °C) during heating was determined. The changes in carbide content and grain size of W-Mo-V high-speed steel at different tempering temperatures were calculated using JMatPro software. Combined with analysis of Ac1 and Accm temperature points, it was found that the optimal annealing temperatures were 817–827 °C, quenching temperatures were 1150–1160 °C, and tempering temperatures were 550–610 °C. The scanning electron microscopy (SEM) examination of the samples obtained with the aforementioned heat treatment parameters revealed that the martensitic substrate and vanadium carbide grains were finely and evenly scattered, consistent with the simulation results. This suggests that the simulation is a useful reference for guiding actual production.

X-Ray Diffraction Analysis of Sigma-Phase Evolution in Equimolar AlCoCrFeNi High Entropy Alloy

Novel equimolar AlCoCrFeNi high entropy alloy (HEA), as a promising candidate for demanding engineering applications has recently received considerable attention due to its random solid solution structure. It confers its synergy of high strength, ductility, high-temperature structure stability and corrosion resistance. Thermally assisted spinodal dissolution from BCC random solid solution (B1) to ordered BCC (B2) and precipitation of brittle σ-phase renders its ability to undergo as an alloy for thermomechanical processing. Therefore, it was necessary to manifest σ-phase nucleation and growth from homogenization temperature (1250oC) at different cooling rates, i.e., furnace cooled and water quenched along with variation in σ-phase crystallite size at transformation temperature (800oC) in Fibonacci time frame (1h, 2h, 4h, 8h, and 16h) to know hot working temperature range and post treatment. An equimolar AlCoCrFeNi high-entropy alloy fabricated via vacuum induction melting was subjected to ICP-MS and XRD analysis to confirm its chemical composition and crystal structure distribution. The XRD results were further analyzed by using Scherrer’s equation and Williamsons-Hall plot to calculate the crystallite size of σ-phase and its associated microstrain. The work aimed to determine the σ-phase reversibility from homogenization temperature 1250oC and crystallite size growth at transformation temperature (800oC) to reveal the importance of thermomechanical processing parameters of equimolar AlCoCrFeNi HEA. In the present study, remarkable retention of the FCC phase was witnessed during furnace cooling and its traces appeared during rapid cooling. The vital phenomenon of FCC-phase nucleation signifies the key importance of the transformation zone, revealing its effect on the post-treatment cooling rate. However, its coupled phenomenon of the tetragonal σ-phase formation remained suppressed during cooling from homogenization temperature (1250οC). It determined the wide hot workability range of equimolar AlCoCrFeNi HEA to make it a suitable candidate for bulk engineering applications.

Powder Metallurgy Processing to Enhance Superelasticity and Shape Memory in Polycrystalline Cu-Al-Ni Alloys: Reference Material for Additive Manufacturing.

Shape memory alloys (SMAs) are functional materials with a wide range of applications, from the aerospace sector to the biomedical field. Nowadays, there is a worldwide interest in developing SMAs through powder metallurgy like additive manufacturing (AM), which allows innovative building processes. However, producing SMAs using AM techniques is particularly challenging because of the microstructure required to obtain optimal functional properties. This aspect is critical in the case of Cu-Al-based SMAs, due to their high elastic anisotropy, making them brittle in polycrystalline form. In this work, we approached the processing of a Cu-Al-Ni SMA following a specific powder metallurgy route: gas atomization of a pre-alloyed melt; compaction of the atomized powders through hot isostatic pressing; and a final hot rolling plus thermal treatments. Then, the microstructure of the material was characterized by electron microscopy showing a specific [001] texture in the rolling direction that improved the functional behavior. The successive processing steps produce an increase of about 40 °C in the martensitic transformation temperatures, which can be well controlled and reproduced through the developed methodology. The thermomechanical functional properties of superelasticity and shape memory were evaluated on the final SMA. Outstanding, fully recoverable superelastic behavior of 4.5% in tension, as well as a ±5% full shape memory recovery in bending, were reported for many cycles. These experiments demonstrate the enhanced mechanical and functional properties obtained in polycrystalline Cu-Al-Ni SMAs by powder metallurgy. The present results pave the road for producing this kind of SMA with the new AM technologies, which always produce polycrystalline components and can improve their processes taking the powder metallurgy SMA, here produced, as reference material.

Exploring the Solidification Sequence and Solid-State Transformations in High-Boron Multi-Component Cast Alloys by Differential Scanning Calorimetry

AbstractThe newly designed multi-component (Fe–5 wt.% W–5 wt.% Mo–5 wt.% V–10 wt.% Cr–2.5 wt.% Ti) cast alloys, containing 0.7–1.1 wt.% C and 2.7–3.6 wt.% B, are intended for tribological applications. The present work was aimed at studying the solidification sequence and phase transformation temperature intervals of the above-mentioned alloys, in order to elucidate their structural status and further develop an appropriate heat treatment regime. For this purpose, Differential Scanning Calorimetry (DSC), microstructure observation and thermodynamic modeling were applied. Two temperature ranges of exothermic reaction (caused by the release of latent heat during transformation) were revealed at 1200-1091 °C and ≤400 °C. The first range was caused by the primary carboboride (M(C,B), M2(B,C)5) precipitation, followed by sequential eutectic reactions with the formation of carboborides M2(B,C)5, M7(C,B)3, and M3(C,B). The temperature ranges of eutectic transformations decreased with the increase in carbon and boron contents. Low-temperature exothermic reactions (at 399-181 °C) referred to the transformation of austenite into bainite or martensite. The values of the latent heat of the transformations were calculated and discussed. Graphical Abstract

Design and Prototype Testing of a Smart SMA Actuator for UAV Foldable Tail Wings

The foldable tail wing system of UAVs offers advantages such as reducing the envelope size and improving storage space utilization. However, due to the compact tail wing space, achieving multi-modal locking and unlocking functionality presents significant challenges. This paper designs a new smart SMA actuator for the use of UAV foldable tail wings. The prototype testing demonstrated the advantages and engineering practicality of the actuator. The core content includes three main parts: thermomechanical testing of the SMA actuation performance, structural design of the actuator, and the fabrication and actuation testing of the prototype. The key parameters related to actuation performance, such as phase transformation temperature and actuation force, were determined through DSC and tensile testing. The geometric parameters of the tail wing were determined through kinetics and kinematic analyses. Through the linkage design of two kinematic pairs, the SMA actuator enables both the deployment and locking of the tail wing. The prototype testing results of the folding tail wing show that, after vibration and temperature variation tests, the SMA actuator is still able to output an actuation stroke of 2.15 mm within 20 ms. The SMA actuator integrates locking for both modes of the tail wing and unlocking during mode transitions, offering advantages such as fast response and minimal space requirements. It provides an effective solution tailored to the needs of the foldable tail wing system.

Machine learning aided prediction of martensite transformation temperature of NiTi-based shape memory alloy

The martensitic transformation temperature (Ms) of shape memory alloys plays a crucial role in their performance. To achieve rapid prediction of Ms in shape memory alloys, this study employs machine learning techniques, using NiTi-based SMAs, the most widely used type, as an example. The results show that the gradient boosting machine algorithm provides the best prediction accuracy, with an R² of 0.92 and a mean absolute error (MAE) of 23.42 °C on the test set. Through correlation analysis, recursive feature elimination, and exhaustive search methods, six key features were identified. Subsequently, SHapley Additive exPlanations (SHAP) values were introduced to analyze the model interpretability, revealing the feature importance ranking and the dependence relationship between features and SHAP values. To address the issue of low Ms in NiTi-based shape memory alloys, the concept of high-entropy alloys was introduced. The study designed a TiZrHfNiCu high-entropy shape memory alloy and efficiently screened alloy compositions using the predictive model. This approach successfully increased the Ms, with the Ti19Zr19Hf19Ni37Cu6 alloy exhibiting an Ms exceeding 400 °C, significantly enhancing high-temperature application performance.

An efficient low-grade thermal energy dual-driven elastocaloric cooling system: Thermodynamic cycle analysis, economic and sustainability assessment

Elastocaloric cooling is regarded as the most promising emerging refrigeration technology, with heat driven elastocaloric cycles at the forefront of research. However, existing systems often have actuators with a mass of 4–20 times that of the refrigerant, resulting in bulky structures and low thermodynamic efficiency. Enhancing system compactness and efficiency has thus become a critical research challenge. This study proposes an innovative low-grade thermal energy dual-driven elastocaloric cooling system, achieving a 1:1 mass ratio (mActuator/mRefrigerant) between the actuator and refrigerant, significantly improving system compactness and coefficient of performance while effectively reducing costs. A three-dimensional numerical and geometric model was developed to analyze the thermodynamic cycle, examining the effects of material, operational, and geometric parameters on cooling performance, and a “category-wise optimization” strategy was employed to determine optimal parameter combinations. The cost and environmental impacts of the new system were evaluated and compared with vapor-compression air conditioning. Results show that the difference in transformation temperatures between austenite and martensite phases significantly impacts cooling performance. Optimal flow rates and cycling frequencies are essential to avoid performance loss. Considering the coefficient of performance and heat transfer, a 1:1 mass ratio is optimal for geometric parameters. The system achieves a maximum coefficient of performance of 0.158, exceeding the existing two schemes by more than 2 times and 7 times, with a maximum temperature rise of 13.1 K. The proposed system is economically feasible and environmentally friendly, providing valuable theoretical foundations and technical solutions for developing sustainable alternative refrigeration technologies.

Development and characterization of PLA food packaging composite

AbstractThis study focuses on the development of bioactive packaging materials by incorporating grape pomace and copper particles into polylactic acid (PLA) composites. The goal is to increase the shelf life of packaged foods while benefiting the health of consumers through the use of these active materials. 6 recipes of composite materials based on polylactic acid and Proviplast 2624 plasticizer were obtained. The additives added were: grape pomace, added at 0.5%, 1% and 1.5%, and copper particles, formed using PEG 600 + CuSO₄, added at 2%, 5% and 8%. Material characterization techniques: FTIR Spectroscopy, used to study the chemical structure. Differential scanning calorimetry (DSC): examined thermal transitions such as glass transition and melting temperatures. Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG): evaluated thermal stability and degradation temperatures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM): analyzed the surface morphology and structure. Mechanical tests: evaluated tensile strength, elongation at break and flexibility.Thermal property analyzes revealed that the additives acted as plasticizers, reducing the intermolecular forces between PLA chains, which decreased the glass transition temperature (Tg), cold crystallization temperature (Tcc) and melting temperature (Tm). The addition of grape pomace and copper particles decreased the degradation temperature of PLA composites, indicating a slight reduction in thermal stability. The transformation temperatures changed and the nature of the thermal transitions (exothermic or endothermic) varied with additive concentrations. Mechanical properties indicated a reduction in tensile strength with increasing additive concentration. Elongation at break and longitudinal modulus of elasticity increased significantly, especially with grape pomace, improving the flexibility of PLA. These changes indicate that the material can absorb more energy before breaking, making it more ductile and more suitable for flexible packaging applications. Increased flexibility and improved thermal resistance ensure that these materials can withstand the demands of packaging, handling and shipping. The combination of improved flexibility, thermal resistance and moderate tensile strength makes these PLA-based composites incorporated with grape pomace or copper particles, enhance the aspect of sustainability by recycling agricultural waste, making the material both ecological and functional, making it a viable option for active food packaging.

Influence of the grain size on the martensitic transformation and strain nanodomains in the Ti-Hf-Ni-Cu shape memory alloy

The martensitic transformation and strain nanodomain were studied in the Ti40.7Hf9.5Ni44.8Cu5 shape memory alloy, whose grain size varied from 130 μm to 160 nm. The largest average grain size (600 μm in length and 130 μm in diameter) was found in the CAST sample. The grains with the smallest size (160 nm) formed during the crystallisation of thin ribbons obtained by the melt spinning technique from the Ti40.7Hf9.5Ni44.8Cu5 ingot (labelled as RIBBON). The average grain size (16 μm) was observed in the sample subjected to high-pressure torsion and post-deformation annealing (labelled as HPT). It was found that the CAST and HPT samples included the NiTi-based matrix and the Ti2Ni-type precipitates, whereas the RIBBON sample contained the NiTi-based matrix only. Regardless of the grain size, all samples underwent the B2 ↔ B19’ transformation on cooling and heating. A decrease in grain diameter from 130 μm to 160 nm decreased the transformation temperatures by more than 100 °C but did not affect the sequence of the transformation. The strain nanodomains formed in all samples on cooling prior to the forward martensitic transformation. The smaller the grain size, the larger the temperature range of the strain nanodomain existence. On heating of HPT and RIBBON samples, the B19 phase transformed to the B2 phase with strain nanodomains, which disappeared only on heating over 120 °C. The influence of grain size on the martensitic transformation and strain nanodomains was analysed from the thermodynamics approach.

Metallic Glass Nanoparticles Synthesized via Flash Joule Heating for High Performance Catalysis

Metallic glasses (MGs) are a class of amorphous metal materials with remarkable properties. By leveraging an abundance of uncoordinated active sites that can serve as catalytic regions, MGs can have high catalytic activity and long-term stability as compared to their crystalline counterparts. Conventional synthesis methods cannot produce nanosized MGs with precise control over composition, phase, and morphology. This work presents flash Joule heating (FJH) as a novel one-step approach to synthesize fully amorphous MG nanoparticles while enabling unprecedented control over these critical parameters. The rapid heating (up to 2505 K/s) and ultrafast cooling rates (up to 1485 K/s) in FJH surpass the critical rates required for glass formation in metal-phosphide alloys like Pd-P, Pd-Ni-P, and Pd-Cu-P, preventing crystallization. Characterization techniques such as SAED, XRD, and XPS have confirmed the amorphous nature and metallic states of the nanoparticles.Remarkably, FJH allowed precise tuning of ternary alloy compositions spanning wide ranges from Pd-rich to Ni/Cu-rich regimes, closely matching designed precursor ratios. The technique significantly expanded the glass formation region compared to conventional methods, accessing previously unattainable compositions like binary Pd3P. Moreover, FJH enabled control over particle size from 2.33±0.83 nm to 36.5±10.1 nm with narrow distributions by optimizing precursors, thermal profiles, and alloy chemistries. Incorporation of multiple elements facilitated smaller nanoparticle formation due to enhanced entropy, reduced melting points, and decreased surface tension.The amorphous MG nanoparticles exhibited outstanding electrocatalytic performance and remarkable stability superiorities over their crystalline counterparts. For the oxygen evolution reaction, Pd-Ni-P MGs displayed ultra-low onset potentials ~300 mV below pure Pd and retained stable activity over 60 hours, contrasting rapid deactivation of crystalline samples of the same composition within 1 hour. PdCoP MGs for methanol oxidation showed high reaction rates and resilience against activity decline during accelerated durability testing, unlike rapidly decaying crystalline variants. This FJH synthesis approach unlocks new opportunities to realize the full potential of MGs by expanding the compositional space of alloy systems with precise control over MG properties, unlocking potential future transformative catalysts.Figure 1: Schematics for (a) a traditional heating-cooling process and (b) the FJH process. (c) Illustration of temperature vs. time diagram of supercooled liquid alloys and glass transformation.(d) Ternary phase diagrams of the Pd-Ni-P and Pd-Cu-P systems. Figure 1

Design and Construction of Analog Water Heater Chamber (AWHC) for Sma Rod and Spring Tensile Testing

This study details the design and construction of an Analog Water Heater Chamber (AWHC) specifically tailored for tensile testing of Shape Memory Alloy (SMA) rods and springs. The AWHC is designed to simulate various temperature conditions, enabling precise control over the thermo-mechanical behavior of SMA specimens. Energy conversion from the electrical to heat form is achieved using an electrical heating element of 1000 watts. This heat is transferred to the SMA spring/wire using convection using a water medium, and phase transformation occurs. The chamber's unique design allows for real-time monitoring of deformation and recovery processes under controlled temperature and loading conditions. Different test results for both the SMA rod and SMA spring at various loading rates and constant temperature, and continuous loading rate and different temperatures showed a good thermo-mechanical coupling result The AWHC's performance was validated through tensile testing of SMA rods and springs, demonstrating its efficacy in evaluating the mechanical properties and phase transformation temperatures of these materials. The results show excellent correlation with theoretical predictions, confirming the AWHC's suitability for characterizing SMA behavior under diverse thermal and mechanical conditions. This research contributes to the development of efficient testing protocols for SMA components, paving the way for their enhanced integration into various engineering applications, thus the aim of which AWHC is designed for is achieved.

A new understanding of phase transformation in vacuum electron beam welding of NS163 Co-based superalloy and AISI 410L stainless steel: Based on in situ observation and variant selection

This study establishes a link between crystallographic variants and mechanical properties at both the edge and center regions of NS163 Co-based superalloy wires and AISI 410L stainless steel plates welded joints. The thermal cycle of vacuum electron beam welding was simulated using in situ laser confocal microscopy to clarify the martensitic transformation process. Results indicate that martensite preferentially nucleates at grain boundaries, maintaining the Kurdjumov-Sachs orientation relationship with the parent austenite. Most variant boundaries in these regions correspond to variants within the same crystal packet, with V1/V3&V5 emerging as dominant pairs. At the edge, the increased cooling rate and temperature gradient amplify the driving force for martensitic transformation, fostering the generation of diverse variants. Conversely, lower cooling rate at the center raises the martensitic transformation temperature and expands variant selection. The study notes significant dislocation slip during micropillar compression, with the edge of weld exhibiting finer martensite laths and dense dislocations, which enhances strength (∼1279 MPa) compared to the center (∼1040 MPa), aligning with the results obtained via nanoindentation. The observed "size effect" results in a twice strength as measured by micropillar compression compared to nanoindentation. Additionally, staggered Bain groups at the edge include a greater number of high angle grain boundaries, indirectly improving toughness. This research aligns with recent literature and aids in the development of compositional design and machining techniques for heterogeneous welds.