To improve the yield strength of metastable β-Ti alloys with transformation-induced plasticity (TRIP) and twinning-induced plasticity effects, a novel strategy combining heterostructure strengthening with the TRIP effect was developed. A metastable β-Ti alloy with a nominal composition of Ti–4Mo–3Cr–1Fe–1Al was used as the base alloy. By adjusting the annealing temperature after cold rolling, heterostructured samples comprising soft recrystallized β-grains and hard un-recrystallized β-grains and α-phase were prepared. Compared with the homogeneous coarse-grained sample, the yield strength of the heterostructured sample significantly increased from 610 to 905 MPa, while maintaining excellent plasticity (32.7
Thermal management is critical for the durability of smart electronic devices, as high current densities generate excessive heat that fully dense heat sinks cannot effectively dissipate. Conductive and convective heat transfer methods, such as combining thermally conductive metals with cooling fans, are challenging due to compact device designs. In this study, we investigate the thermal properties of noble metal-decorated graphene nanoplatelet-reinforced Cu composites (Au-GNP/Cu, Ag-GNP/Cu, and Ag-N-GNP/Cu) with optimized porosity (i. e., lowest and highest), building on our previous work on their physical and mechanical properties. The thermal performance of these composites as heat sinks for LED lights was compared to undecorated GNP/Cu, sintered Cu, and commercial Cu. Decorated GNP/Cu composites exhibited enhanced thermal conductivity over undecorated GNP/Cu and sintered Cu, though values remained below commercial Cu due to porosity. High-porosity samples demonstrated superior cooling, with 0.1-Ag-GNP/Cu (22.94 % porosity) reducing LED operating temperatures by 15.83 % compared to sintered Cu. Sintered Cu (18.64 % porosity) also outperformed commercial Cu (0.11 % porosity), lowering LED temperatures by 8.57 %, highlighting the role of porosity in convective heat transfer. LED Luminous efficiency remained above 90 % for all composites, peaking at 97.21 % for 0.1-Ag-GNP/Cu. The study concludes that Ag-GNP/Cu composites effectively enhance thermal management through combined conductive and convective mechanisms, offering a promising solution for compact electronic devices.
Ti-6Al-4 V is an (α + β) titanium alloy that has been most widely used in automotive, aerospace, and biomedical applications due to the extensive material properties of high strength, toughness, high strength-to-weight ratio, and biocompatibility. Machine learning (ML) algorithms of data-driven methods provide a better understanding of the correlation between material properties and tribological properties. Correlations of tribological test variables (sliding speed, sliding distance, and normal load) with the tribological properties (coefficient of friction and wear rate) were studied using machine learning algorithms. A total of 41 data points based on the Ti-6Al-4 V alloy coating were divided into training and testing sets in the ratio of 80:20. The ML-based algorithms, which include Decision Tree (DT) and Random Forest (RF) algorithms, have been studied to predict the wear rates and coefficient of friction. The evaluation metrics like MAE, MSE, and RMSE are used to find the best suitable algorithm for the predictions. Using the data analysis, the coefficient of friction and wear rates have been satisfactorily predicted from the considered data sets.
Knowledge about the thermodynamic equilibria of the Al2O3–TiO2–CaO system is important for the design of refractory and ceramic materials. The Al2O3–TiO2, Al2O3–CaO and CaO–TiO2 binary systems were reoptimized and the Al2O3–TiO2–CaO ternary system was assessed by CALPHAD (CAlculation of PHAse Diagram) approach due to the reliability of phase diagram and thermodynamic property data. The liquid phase was described by the ionic two-sublattice model with the formula (Al+3,Ti+2,Ti+3,Ca+2)P(O−2,AlO1.5,Va,O,TiO2)Q. A set of self-consistent thermodynamic parameters for the Al2O3–TiO2–CaO ternary system was finally obtained, reproducing well the phase diagram and thermodynamic properties, predicting the Ca4Ti3O10 primary crystallization field. The present thermodynamic description is of interest for the design of refractory and ceramic materials as well as the development of thermodynamic databases for multicomponent aluminosilicate system.
Through the addition of minor alloying elements, we have designed and prepared a new non-equiatomic sixmembered Fe41Ni20Co20Cr10Al5V4 (at. %) high-entropy alloys (HEAs), with the aim of further improving HEA performance. The effect of annealing temperature on HEA microstructure and mechanical properties was systematically studied by using a variety of characterization methods. The results show that HEA Fe41Ni20Co20Cr10Al5V4 is a single-phase face-centered cubic (FCC) solid solution structure. The yield strength HEA Fe41Ni20Co20Cr10Al5V4 doped with minor element doped is 15% higher than that of the base alloy Fe40Ni20Co20Cr20 with a similar grain size while retaining good plasticity (elongation >50%). This can be attributed to the increased lattice distortion induced by the doping elements (i.e., Al and V). In addition, the strengthening mechanisms of Fe41Ni20Co20Cr10Al5V4 HEAs were analyzed. HEA strengthening mechanisms mainly include solid-solution strengthening, grain-boundary strengthening, and dislocation strengthening. Among them, in partially recrystallized HEA, fine-sized dislocation cells formed by the intertwining of high-density dislocations significantly increase material strength. Due to the excellent plasticity (similar to 61%) inherent in HEA as-homogenized, further research can be carried to improve its strength with minimal compromise to plasticity in order to achieve a better balance between strength and ductility.
A soft i1 (Al2.68Ag0.32Zr) shell and hard i2 (Al1.84Ag0.16Zr) core, were formed in the Al0.46Ag0.32Zr0.22 alloy by annealing. The microstructure, crystal structure, and hardness of the core-shell structure were characterised in detail. Compared with the as-cast sample, the sample annealed at 500 degrees C for 120 days formed i1 at the interface of the i2 phase. The coexistence of some i1 grains and the (Ag) matrix was observed. Additionally, nano-indentation demonstrated that the hardness values of i1 and i2 were 3.82 and 10.20 Gpa, respectively. The formation of a hard-soft core-shell structure may enhance comprehensive performance of the material.
In the downstream of the Oil & Gas industry and decline in oil production, the NiAl-HT derived hydrotalciteis a candidate as catalyst to produce syngas in the methane dry reforming process. Hydrotalcite are lamellar compounds of general formulation[M1-x 2+ Mx 3+ (OH) 2]x+[An-] x/n .m H2Owhere the ionic or cationic character can be tuned by the choice of the metal nature and oxidation degree. NiAl-SPC samples were obtained by coprecipitation at constant alkaline pH, then the product was thermal treated at 450°C for 6h to obtain mixed oxides phases. Samples prior and after calcination were characterized by XRD, ICP, BET, FTIR, SEM, TEM, TPR, TGA/DTA and Raman. Catalysts were examined in CO2 dry reforming of methane to examine the influence and the role of the reducibility ability on the catalytic reactivity and stability of NiAl-SPC hydrotalcite generics. They were reduced at 500°C, 600°C, and 700°Cfor 1h to evaluate the effect of its morphology changes on the carbon dioxide reforming of methane carried out at 700°C versus time on stream. It was shown that the reduction conditions strongly influence the reactivity of Ni metallic active phase catalyst, catalytic selectivity and its resistance to carbone deposit for methane reforming by carbon dioxide.This study proposes a further understanding of the synthesis, effects of additives and treatment of hydrotalcite as a catalyst for the DRM reaction. This knowledge will also be beneficial for the development of catalysts for other high temperature industrial applications (ammonia cracking, alcohol to hydrogen conversion...) and for longer term applications such as drug delivery or energy storage materials.
The phase equilibria of the Al-Ag-Si ternary system at 500 degrees C and 600 degrees C were investigated by X-ray powder diffraction (XRD) and electron probe microanalysis (EPMA). Three two-phase regions ((Al) + (Si), (Si) + Ag2Al, and (Si) + (Ag)) and two three-phase regions ((Si) + (Ag) + Ag2Al and (Si) + (Ag) + Ag2Al) were observed at 500 degrees C. The (Si) + Ag2Al and (Si) + (Ag) two-phase regions and (Si) + Ag2Al + liquid and (Si) + (Ag) + Ag2Al three-phase regions were identified in the isothermal section at 600 degrees C. A vertical section of the Al-Ag-Si system along Al0.6Si0.4-Al0.8Ag0.2 was investigated using differential scanning calorimetry (DSC) from which the tem-peratures of the phase-transition reactions were determined. The isothermal and vertical sections obtained in this study provide fundamental data for the thermodynamics of the Al-Ag-Si system and knowledge of the ther-modynamics associated with aluminium-based alloys.
The investigation of the Al–Ag–Zr system is crucial for the development of heat-resistant Al alloys, which are essential for applications in high-temperature environments. In this work, we first determined the isothermal sections of the Al–Ag–Zr system at 500 and 600 °C using equilibrium alloys. Simultaneously, the τ 3 (Al 6 AgZr 6 ) phase was identified by transmission electron microscopy (TEM). In addition, the three-phase equilibrium of τ 3 + AgZr + (Ag) instead of Al 3 Zr 4 + AgZr + (Ag) was confirmed at 500 and 600 °C. The formation enthalpies of the end-members and ternary compounds in the Al–Ag–Zr system were calculated via first-principles calculations. Based on the experimental and computational results, a thermodynamic database of the Al–Ag–Zr system was established using the CALPHAD (calculation of phase diagrams) method. The hardness of τ 1 (Al 2.68 Ag 0.32 Zr) and τ 2 (Al 1.84 Ag 0.16 Zr) were determined to be 3.82 and 10.20 GPa, respectively, using nanoindentation. The introduction of the τ 2 phase in the design of Al alloys can considerably increase the mechanical properties of the alloys.
Intumescent fire-retardant coating is a passive type of protection against fire, design to reduce the heat transfer from the source of fire to the steel substrate in a duration of time. This research investigates the effect of Magnesium Oxide as a filler in expandable graphite-based intumescent fire-retardant coatings. The coating was developed by varying weight percentage (0.5–2.5wt%) of magnesium oxide towards binder in the coating in addition to ammonium polyphosphate, melamine, boric acid, zinc borate, and expandable graphite. The samples were subjected to fire tests to investigate their performance. The heat shielding fire test shows a decrease of back substrate temperature when increasing the amount of magnesium oxide in the formulation up to 242 ℃ for 1 h. The samples were subjected to a fire control test to investigate the intumescent factor (IF) at 600 ℃ for 1 h in a carbolite furnace. MG1.5 shown the highest with the expansion of 8.33 Intumescent factor. Thermal gravimetric analysis, water immersion, and adhesion tests were also performed to study the sample's thermal stability and adhesion strength towards the substrate. The result showed that adding magnesium oxide in the formulation of intumescent coating improved the coating's thermal performance, thus increasing the protection time of steel substrate.
In recent decades, considerable attention has been paid to the catalytic dry reforming of methane to obtain syngas. This reaction has very important environmental implications due to the utilization of CH 4 and CO 2 , gases that contribute to the greenhouse effect. The dry reforming of methane is normally carried out over strong basic catalysts with noble metals. Nickel has emerged as an interesting alternative, although it tends to deactivate and form carbon whiskers, which could block the reactor. It is therefore necessary to improve their catalytic performance (conversion, selectivity and stability). In this work, Ni 0.69 La 0.31 and Ni 0.14 Mg 0.55 La 0.31 were studied in the dry methane reforming reaction. The precursors were prepared by co-precipitation and the oxide phases were obtained by calcining these precursors at 450°C/6 h. The XRD diagrams of the calcined samples show the formation of mixed oxide phases with a periclase-like structure. Analysis of the temperature-programmed reduction shows that the presence of Mg shifts the reduction to higher temperatures. The catalysts, reduced at 650°C, were tested in this reaction as a function of operating time at 650°C. No deactivation occurred after 20 h of operation. Furthermore, the combination of Mg and La drastically improves the conversion and selectivity of the catalyst (> 95%).
Phase equilibria of the Al-Ni-Sc system were investigated by combination of key experiments and thermodynamic modeling. The isothermal sections of the Al-Ni-Sc ternary system in the (Al, Ni)-rich region at 873K and 673K were investigated using the electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The solubilities of the binary phases in the ternary system were measured. According to the experimental results in this work and related literature, the Al-Ni-Sc ternary system has been optimized by means of the CALPHAD (CALculation of PHAse Diagrams) method. Isothermal sections at 1273, 1173, 873 and 673 K were reproduced. The calculated thermodynamic and phase equilibria data for the ternary system agree well with the experimental data. This work can be used as a basis for the multi-component thermodynamic database of Al-based alloys.
Hydrotalcite catalysts derived from NiAl and NiAlMg mixed oxides were successfully prepared by coprecipitation at a constant pH of 11. Physicochemical methods were investigated to determine their structural and textural properties. Using isopropanol as a probe molecule, the acid–base properties of the catalysts were investigated, and the evaluation of reactivity, selectivity and lifetime was established.
Zirconium phosphate (ZrP) recently introduced in intumescent fire protective coating has shown improvement in developing ceramic layer. The tubular halloysite clay (THC) due to its unique molecular structure can be combined with ZrP to enhance fire resistance by developing a strong silica network on the char surface. This study is aimed to investigate the synergistic effects of tubular halloysite clay and zirconium phosphate fillers to improve the thermal performance of the intumescent coating. The control coating formulation and a range of coating formulations using a combination of weight percentage of THC and ZrP were developed to study the influences of fillers on fire performance. The char expansion and fire resistance tests of the coatings were conducted using furnace fire test and Lab scale fire jet. Thermal stability of the coating was determined by TGA and char was characterized by FESEM, XRD, FTIR and XPS. Water-resistance test of the coating was performed according to ASTM D-870. Results showed that the reinforcement of THC-ZrP showed promising improvement on the performance of IFC and substrate temperature was far below the critical temperature, 550 °C. Sample HZ 5 showed the least backside steel substrate temperature of 219 °C. Expansion rate of char was found reduced with the addition of THC but improved the char compactness. The addition of THC and ZrP in IFC improved 18% fire resistance performance and 5% residual wt. Of char. Char morphology showed silica network, XRD and FTIR confirmed the presence of silicon. Water absorption test showed 95% less water absorption (HZ-5) compared to control coating. Post water immersion, fire test showed 7% increase in substrate temperature which is 18% less than control coating after water immersion fire test.
Co 0.67 Al 0.31 and Co 0.14 Mg 0.54 Al 0.31 hydrotalcite based catalysts were prepared by a co-precipitation method at a fixed pH=11, exhibiting a suitable hydrotalcite structure to be used as a catalyst in the reaction of the dry reforming of methane (DRM). Calcination at 450 °C provides the best conditions to prepare the most adapted structure and morphology to be later used in the DRM reaction. The samples were characterised by XRD, FTIR, SEM and it was shown that they exhibit a specific surface in the 30-70 g/cm 2 and a crystallite size of approximately 20 nm. The results of the TPR analysis showed clearly that CoAl-HT has better catalytic performances than CoMgAl-HT. This result can be explained by the presence of the Co 0 for the catalyst CoAl-HTc-R and the total absence in the sample CoMgAl-HTc-R. The solid CoMgAl-HTc-R requires high reduction temperature compared to CoAl-HTc-R due to the strong CoO-MgO interactions.
The main reason for the high strength in near-β titanium alloys is the ultrafine precipitation of the acicular secondary α phase in the β matrix. The purpose of this study is to use the pseudo-spinodal mechanism to obtain the ultrafine α phase for the design of a new high-strength near-β titanium alloy. Thermodynamic calculations and TC21-(TC21 + 15Mo) diffusion couple composition gradient experiments were used to demonstrate that TC21 + 3Mo alloy can undergo a pseudo-spinodal decomposition to obtain the ultrafine α phase, resulting in a high-strength alloy. By adjusting the heat treatment process to obtain a bimodal microstructure, the alloy exhibits a good balance between ultimate tensile strength (1351 MPa) and plasticity (8.5% strain). Thus, it was demonstrated that the pseudo-spinodal mechanism combined with a high-throughput diffusion couple technique is an effective method for designing high-strength titanium alloys. Pseudo-spinodal mechanism combined with high-throughput diffusion couple technique is an effective method for designing high-strength titanium alloys. TC21 + 3Mo alloy can undergo a pseudo-spinodal decomposition to obtain the ultrafine α phase, resulting in a high-strength alloy. Compared with other alloys, there is considerable potential for application of TC21 + 3Mo alloy.
The polythermal section of Ti-22Al-xNb (30–78 at.% Ti) in the Ti-Al-Nb system was studied using X-ray diffraction analysis (XRD), differential thermal analysis (DSC), and electron probe micro-analysis (EPMA). No new ternary compounds were found in this work. The polythermal section has five three-phase regions, nine two-phase regions, and three single-phase regions. The O phase transition is confirmed to occur below 1000 °C. A four-phase invariant reaction β + σ → O + δ was found at 931 °C.