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Nb-Si based alloys are considered as a potential candidates to substitute for Ni-based super alloys. However, its poor mechanical properties and high temperature oxidation resistance greatly limit its development and application. Alloying can effectively improve the mechanical properties and oxidation resistance of Nb-Si based alloy. In this work, the effects of Al, Cr, B elements addition on the mechanical properties and oxidation resistance of niobium-silicon ternary alloys are summarized. The microstructure, oxidation behavior and mechanical properties of various alloys were analyzed and compared. Moreover, the fracture and oxidation failure mechanism of the alloys are also summarized. Finally, the development trend of ternary Nb-Si based oxidation-resistant alloys in the future has been prospected.

In this work, we have performed a comprehensive investigation of the structural, electronic magnetic, mechanical and thermal properties of the compounds SrFeO 3 and SrMnO 3 under pressure using density functional theory. In structural and mechanical properties, we have found that compounds are stable in the cubic phase by performing stability tests of tolerance factor and mechanical stability criteria, respectively. The bulk modulus, shear modulus and young modulus are observed to increase with pressure, and this illustrates that compounds become more stiff and rigid. The internal strain factor is also observed to decrease with an increase in pressure which is the key parameter in explaining bond bending or bond stretching ability in the material. In electronic properties, we have investigated the electronic band gap and density of states of the compounds in detail. While in magnetic properties, ferromagnetic nature of the compounds is observed throughout the pressure range. The majority of bonds in the studied compounds are ionic according to Cauchy criteria. The superplastic deformation is also calculated using elastic constants which illustrates materials resistance to occur plastic deformation at high pressure in the cubic phase. Our calculated results at 50 GPa are not discussed previously in theoretical or experimental findings. All calculated results at ambient conditions have matched well with available theoretical and experimental results. Our results have indicated all studied compounds as half-metallic in nature which increases the chances of materials to be used in spintronic devices.

Ab initio study of high-pressure phase transition and electronic structure of Fe-doped CeO 2 with Fe concentrations of 3.125, 6.25, and 12.5 at% has been reported. At a constant-pressure consideration, the lattice constants and the volume of the supercell were decreased with an increasing concentration of Fe. The average bond length of Fe–O is lower than that of Ce–O. As a result, Fe doping induces the reduced volume of the cell, which is in good agreement with previous experiments. At high pressure (~ 30 GPa), it was found that the transition pressure from the fluorite to the cotunnite orthorhombic phase decreases at a higher concentration of Fe, indicating that the formation energy of the compound is induced by Fe-doping. Furthermore, compression leads to interesting electronic properties too. Under higher pressures, the bandgap increases in the cubic structure under compression and then suddenly plummets after the transition to the orthorhombic phase. The 3d states of Fe mainly induced the impurity states in the bandgap. In both the undoped and Fe-doped systems, the bandgap increased in the cubic phase at high pressure, while the gap and p-d hybridization decrease in the orthorhombic phase.

We have investigated the high-pressure structural and vibrational behavior of the disordered kesterite-type Cu 2 ZnSnS 4 compound at ambient temperature. Our experimental and theoretical investigations have revealed a clear structural transition to a GeSb-type phase close to 15 GPa, a tetragonally distorted variant of the NaCl-type phase. The latter transformation is accompanied by a cationic coordination increase from fourfold to sixfold with respect to the sulfur anions. In addition, a change in the compressibility rate was detected at about 8 GPa within the pressure stability range of the disordered kesterite-type phase. Upon decompression, a disordered zinc blende/sphalerite structure is recovered. We discuss our findings in close conjunction with our recent high-pressure work on the ordered Cu 2 ZnSnS 4 modification.

A new class of hard materials, Pm-3 m- Os 3 X (X = V, Nb and Ta), is predicted by first-principles calculations based on DFT-GGA. For Pm-3 m- Os 3 X, the mechanical, electronic and thermodynamic properties are studied under high pressure. Their elastic constants and phonon spectra calculated by using GGA indicate that they are mechanically stable and dynamically stable structures at high pressure. The values of Pugh ratio K show that the three compounds are ductility and the ductility increases as the pressure increases. The anisotropies of the Young’s and Bulk moduli are discussed. The results show that their Young's moduli have strong anisotropy, and the bulk moduli are almost isotropic. The band structures calculated by using GGA show that they have metallic properties. The DOS is derived mainly from the contributions of the Os \"d\" and X \"d\" state. The calculated enthalpies of formation prove their thermodynamic stability. Based on the phonon spectrum method, the thermodynamic properties from 0 to 1000 K are predicted at high pressure. The thermodynamic properties of Pm-3 m- Os 3 X are basically similar.

Mn 2 O 3 is a significant candidate for various applications. In the present work, the Mn 2 O 3 nanorods have been successfully prepared through a facile sonochemical method with the aid of a cetyl trimethyl ammonium bromide (CTAB) template. Systematic analyses were done to confirmes the formation and morphological properties of the Mn 2 O 3 materials. It exhibits superior supercapacitor behavior with an electric double layer capacitor-based charge storage mechanism. The freshly prepared Mn 2 O 3 nanorods render the maximum specific capacitance of 647 Fg −1 at a scan rate of 5 mVs −1, whereas the galvanostatic charge/discharge studies offer the specific capacitance of 656 Fg −1 at a current density of 1 Ag −1 . The Mn 2 O 3 nanorods provide the maximum energy and power densities of 91.1 Wh Kg −1 and 1525 Wkg −1, respectively. In addition, the cyclic stability analysis exhibits only 12% initial capacitance degradation over 3000 CV cycles at a scan rate of 100 mVs −1 . The hopeful outcomes demonstrate the significance of the Mn 2 O 3 nanorods as electrode material for supercapacitor devices.

The shape memory performance of the Fe-Mn-Si shape memory alloy is not satisfactory due to irreversible plastic deformation during the martensitic transformation process. In this paper, Fe14Mn6Si9Cr5Ni alloys with different B additions were prepared by arc additive manufacturing using Fe14Mn6Si9Cr5Ni-xB alloys with good overall performance. The memory properties of the prepared alloys were investigated, the microstructure of the alloys was analyzed, and the mechanism of B's influence on the shape memory alloys was discussed. The results showed that adding B improved the alloy's recoverable strain. The recoverable strain of a Fe14Mn6Si9Cr5Ni-xB alloy can reach up to 3.01% when 0.05 wt.% of B is added. The analysis indicated that the addition of B reduced the alloy's stacking fault energy, increased the strength of the parent phase, and increased the number of stress-induced martensite. However, when B is added above 0.1 wt.%, larger-sized borides precipitate in the alloy. These larger-sized borides exhibit a pinning effect, causing cross-growth of martensite and deteriorating the memory performance of the alloy.

The article presents a hybrid method for calculating the chemical composition of steel with the required hardness after cooling from the austenitizing temperature. Artificial neural networks (ANNs) and genetic algorithms (GAs) were used to develop the model. Based on 550 diagrams of continuous cooling transformation (CCT) of structural steels available in the literature, a dataset of experimental data was created. Artificial neural networks were used to develop a hardness model describing the relationship between the chemical composition of the steel, the austenitizing temperature, and the hardness of the steel after cooling. A genetic algorithm was used to identify the chemical composition of the steel with the required hardness. The value of the objective function was calculated using the neural network model. The developed method for identifying the chemical composition was implemented in a computer application. Examples of calculations of mass concentrations of steel elements with the required hardness after cooling from the austenitizing temperature are presented. The model proposed in this study can be a valuable tool to support chemical composition design by reducing the number of experiments and minimizing research costs.

Five algorithms of Gaussian process regression, artificial neural network (ANN), support vector machine, boosted trees, and genetic algorithm artificial neural networks (GAANN) are used to model high manganese steel's processing parameters, chemical composition, and mechanical properties. The results show that the ANN model optimized by applying the GAANN with topology [25, 25] has the highest prediction accuracy. Based on the network calculated using the GAANN, the price optimization of the target performance is achieved by introducing the price factor and the target performance in the fitness function. The NSGA-II algorithm is applied to design ultra-high manganese steel's processes and chemical composition. The predicted performance is much higher than the highest value in the original data, and the calculation results all have an accuracy of about 94%. The developed material design model is applicable to high manganese steel and can be used to design other alloys, which provides a good direction for machine learning to design multi-component alloy materials.

The lack of a mechanistic framework for chemical reactions forming inorganic extended solids presents a challenge to accelerated materials discovery. We demonstrate here a combined computational and experimental methodology to tackle this problem, in which in situ X-ray diffraction measurements monitor solid-state reactions and deduce reaction pathways, while theoretical computations rationalize reaction energetics. The method has been applied to the La₂CuO4–xSₓ (0 ≤ x ≤ 4) quaternary system, following an earlier prediction that enhanced superconductivity could be found in these new lanthanum copper(II) oxysulfide compounds. In situ diffraction measurements show that reactants containing Cu(II) and S(2−) ions undergo redox reactions, leaving their ions in oxidation states that are incompatible with forming the desired new compounds. Computations of the reaction energies confirm that the observed synthetic pathways are indeed favored over those that would hypothetically form the suggested compounds. The consistency between computation and experiment in the La₂CuO4–xSₓ system suggests a role for predictive theory: to identify and to explicate new synthetic routes for forming predicted compounds.