Intermetallic Materials Research Articles

Strengthening of additively manufactured Me-Si-B (Me = Mo, V) by Y2O3 particles

In the present study a new approach on strengthening of innovative high-temperature Me-Si-B (Me = Mo, V) materials by Y2O3 particles is presented. This approach combines the oxide dispersed strengthening (ODS) mechanism and additive processing of innovative intermetallic materials. To this end, gas atomized powder material, suitable for additive manufacturing, was doped with Y2O3 particles. Bulk materials were manufactured via direct energy deposition (DED), which is an efficient method to generate crack-free Me-Si-B alloys. The DED process further allows the homogeneous distribution of Y2O3 particles in the intermetallic matrix. Hardness measurements as well as uniaxial compression tests depict the potential of novel Y2O3 reinforced Me-Si-B alloys.

Regularities of hydrogen accumulation and distribution in titanium coatings formed on a steel substrate by the cathode-arc method

The main direction in the field of the use of hydrocarbon resources is the creation of a metal hydride hydrogen battery. Hydrides are solid non-volatile substances that are formed when certain metals are combined with hydrogen. The principle of using hydrides as a medium for storing hydrogen is simple: under pressure, the metal captures hydrogen, which dissolves in the metal, forming a new chemical, and when the hydride is heated, the gas is given back. The metal hydride method of hydrogen storage is based on the ability of a number of intermetallic compounds, metals, alloys and composite materials to reversibly and selectively absorb hydrogen. The object of the study is titanium coatings formed on samples of 12X18H10T stainless steel by the cathode-arc method. In the course of the study, ion-plasma deposition of coatings was carried out. Scanning electron microscopy was also performed. The phase composition and structure of the titanium coating in the initial and submerged state were evaluated. Gas-phase hydrogenation was carried out, followed by an assessment of the effect of hydrogen on the alloy structure. Titanium was deposited by the cathode-arc method. Deposition of titanium coatings was carried out on the Raduga-Spektr installation, microstructure analysis was carried out on SEM using a Hitachi TM–2800 gas-phase hydrogen saturation microscope using an automated Gas Reaction Controller complex, a Shimadzu XRD-7000S diffractometer, and an inert gas melting method using a LECO RHEN 602 hydrogen analyzer.

Highly reversible lithiation/delithiation in indium antimonide with hybrid buffering matrix

Sb-based intermetallic materials have been extensively studied as electrodes for lithium-ion batteries (LIBs) owing to the high discharge capacity and acceptable working voltage range. In this study, InSb nanocrystallites were homogeneously distributed and embedded into a combined matrix of amorphous carbon and rutile TiO2 by a facile two-time ball-milling process. The nanostructure of the composite exhibited a favorable synergistic effect of the three components (InSb: high-capacity active material, TiO2: inorganic crystalline robust matrix, and C: carbonaceous amorphous conductive matrix), which not only supplied a buffering network to suppress the volume expansion of InSb during the Li+ ion intercalation/deintercalation process, but also enhanced the ionic/electronic conductivity of the anode material. Consequently, the InSb-TiO2-C anode delivered a long lifespan and remarkable rate performance. In addition, the anode showed a high reversible discharge capacity of 540 mAh g−1 even after 400 cycles at a high current rate of 500 mA g−1. Furthermore, the anode exhibited good capacity retention (87% at 2 A g−1 relative to the capacity at 0.1 A g−1). These results indicate the potential of InSb-TiO2-C nanocomposites for LIBs anode materials.

Effect of Al Additions on the Microstructure and Mechanical Properties of the SHS Product of Ni-Al-TiO<sub>2 </sub>Mixtures

Intermetallics have attracted much interest in the high-temperature application. The Self-propagation High-temperature Synthesis (SHS) process offers an effective route to synthesize the intermetallic materials. However, an excessive composition of the SHS reactant can affect the structure and properties of the synthesized product. In this work, the SHS process was used to synthesize the mixture of Ni, Al, and TiO2 with different Al additions. The structure and properties of the product were characterized by SEM, EDS, and XRD tests. The mechanical properties of the product were evaluated by a Vickers microhardness test. The result shows that several intermetallic phases such as NiAl, TiNi, and TiAl were formed in the synthesized product. The formation of oxide appeared in the product due to the product reaction as well as the air environment. An increased Al addition resulted in decreased pores and increased hardness. The addition of 1.11 wt.% Al achieved the maximum hardness of the product. However, cracks were observed in the sample with the highest hardness. Excessive addition of Al decreased the hardness.

Towards additive manufacturing of magnetocaloric working materials

The feasibility of three-dimensional printing via the Directed Energy Deposition (DED) technique is demonstrated for the ferromagnetic AlFe2B2 (aka 1-2-2) compound, which shows promise as a working material for room-temperature magnetocaloric devices. Like many intermetallic materials, the 1-2-2 compound is brittle at room temperature; not only is it difficult to synthesize from the melt, it is challenging to form it into useful geometries necessary for effective heat transfer in magnetocaloric devices. Using Laser Engineered Net Shaping (LENSTM) synthesis from two powder precursors, AlB2 and Fe, samples of simple (rod) and complex (honeycomb) architectures were successfully synthesized. The phase constitution and distribution, magnetic transition temperature, and saturation magnetization determined for the LENSTM-synthesized rod sample are all similar to those obtained for 1-2-2 materials made by conventional casting. Further, the measured magnetic entropy change, as determined from Maxwell's Relations applied to magnetic data, indicates that the magnetocaloric response of the annealed LENSTM-printed rod samples are comparable to those of the 1-2-2 compounds made by conventional techniques. These results confirm that complex magnetofunctional shapes, which are needed for efficient energy conversion in magnetocaloric devices, can be rapidly fabricated from the AlFe2B2 compound.

Development of TiAl-Si Alloys-A Review.

This paper describes the effect of silicon on the manufacturing process, structure, phase composition, and selected properties of titanium aluminide alloys. The experimental generation of TiAl–Si alloys is composed of titanium aluminide (TiAl, Ti3Al or TiAl3) matrix reinforced by hard and heat-resistant titanium silicides (especially Ti5Si3). The alloys are characterized by wear resistance comparable with tool steels, high hardness, and very good resistance to oxidation at high temperatures (up to 1000 °C), but also low room-temperature ductility, as is typical also for other intermetallic materials. These alloys had been successfully prepared by the means of powder metallurgical routes and melting metallurgy methods.

First Mo–Bi intermetallic material

Materials Discovery Despite ordered structure and well-defined stoichiometry, stable intermetallic compounds are challenging to predict even in binary systems because of the numbers of structures that depend on chemical composition and need to be considered. Incorporation of Bi is of particular interest because of the potentially distinctive properties that it could introduce into intermetallic materials. Using a density functional theory–based random structure searching approach, Altman et al. explored the high-pressure phase space of the Mo–Bi system and predicted stability of the stoichiometric compound MoBi2 of the CuAl2 structure type, the first group 6-Bi binary intermetallic structure confirmed experimentally. Additional electronic structure calculations revealed important correlations that could be useful in directing the synthesis of analogous intermetallic compounds of transition metals with Bi. J. Am. Chem. Soc. 143 , 214 (2021).

Crystallographic, magnetic and magnetocaloric properties in novel intermetallic materials R3CoNi (R = Tb, Dy, Ho, Er, Tm, Lu)

A family of novel intermetallic R3CoNi with heavy rare earth ions has been synthesized (R = Tb, Dy, Ho, Er, Tm, Lu) and a study of the crystal structure of these phases performed. All the compounds adopt the rhombohedral Er3Ni2-type structure [Pearson’s symbol hR45; space group R-3h (N. 148)]. A thorough investigation of their magnetic and magnetocaloric properties has been undertaken. Magnetization and ac-susceptibility measurements as a function of temperature show that the samples with Tb, Dy, Ho, Er, and Tm present a paramagnetic to ferromagnetic (PM-FM) transition at temperatures in the range 96–6 K; different reorientation transitions take place below the respective TC, in most cases with thermomagnetic irreversibility. Thermal and magnetic measurements have been used to retrieve the set of critical exponents (α, β, γ, δ) for the PM-FM transition to assign a universality class to Tb3CoNi, Dy3CoNi, and Ho3CoNi, with the result that, in the first case, it is close to the Mean Field model, in the second one it is between the Chiral Heisenberg and the XY-Chiral, and in the third one it is close to the XY-Chiral model. Therefore, in Tb3CoNi the transition is governed by long-range order interactions, whereas in Dy3CoNi and Ho3CoNi there must be some kind of frustrated non-collinear ferromagnetism. The magnetocaloric measurements in five members of the family indicate that all of them present highly competitive magnetocaloric properties in their respective temperature ranges, with high magnetic entropy changes (from 12.8 to 18.5 J/Kg.K at μ0ΔH = 5 T) and refrigerant capacities (from 412 to 699 J/Kg at μ0ΔH = 5 T). These results assess and highlight the applicative interest of these compounds, besides suggesting the possibility of tuning the range of the operating temperature by modifying the rare earth ion. Finally, universal curves for the magnetocaloric properties have been found for Tb3CoNi, Dy3CoNi, and Ho3CoNi; the scaling of the magnetocaloric variables confirms the validity of the assigned universality classes.

ИССЛЕДОВАНИЕ ВЫСОКОТЕМПЕРАТУРНОЙ ИНТЕРМЕТАЛЛИДНОЙ МАТРИЦЫ СИСТЕМЫ Ni–Al–Co ДЛЯ ПОЛУЧЕНИЯ КОНСТРУКЦИОННЫХ СПЛАВОВ С ПОВЫШЕННОЙ ПЛАСТИЧНОСТЬЮ (обзор)

A generalization of the results of scientific and technical publications is presented, the analysis of which will allow to develop scientific foundations for the creation of a new class of heat-resistant structural materials based on intermetallic matrices with increased plasticity at room temperature and high specific strength at temperatures up to 950 °C in the Ni–Al–Co system. It is shown that alloys of the Ni–Al–Co system can be used in the manufacture of rotary parts in the form of gas turbine engine discs (GTE), working at temperatures up to 950 °C, as well as materials for GTE blades due to heat resistance at temperatures up to 1200 °C.

How the in situ monitoring of bulk crystalline phases during catalyst activation results in a better understanding of heterogeneous catalysis.

The present Highlight article shows the importance of the in situ monitoring of bulk crystalline compounds for a more thorough understanding of heterogeneous catalysts at the intersection of catalysis, materials science, crystallography and inorganic chemistry. Although catalytic action is widely regarded as a purely surface-bound phenomenon, there is increasing evidence that bulk processes can detrimentally or beneficially influence the catalytic properties of various material classes. Such bulk processes include polymorphic transformations, formation of oxygen-deficient structures, transient phases and the formation of a metal–oxide composite. The monitoring of these processes and the subsequent establishment of structure–property relationships are most effective if carried out in situ under real operation conditions. By focusing on synchrotron-based in situ X-ray diffraction as the perfect tool to follow the evolution of crystalline species, we exemplify the strength of the concept with five examples from various areas of catalytic research. As catalyst activation studies are increasingly becoming a hot topic in heterogeneous catalysis, the (self-)activation of oxide- and intermetallic compound-based materials during methanol steam and methane dry reforming is highlighted. The perovskite LaNiO3 is selected as an example to show the complex structural dynamics before and during methane dry reforming, which is only revealed upon monitoring all intermediate crystalline species in the transformation from LaNiO3 into Ni/La2O3/La2O2CO3. ZrO2-based materials form the second group, indicating the in situ decomposition of the intermetallic compound Cu51Zr14 into an epitaxially stabilized Cu/tetragonal ZrO2 composite during methanol steam reforming, the stability of a ZrO0.31C0.69 oxycarbide and the gas-phase dependence of the tetragonal-to-monoclinic ZrO2 polymorphic transformation. The latter is the key parameter to the catalytic understanding of ZrO2 and is only appreciated in full detail once it is possible to follow the individual steps of the transformation between the crystalline polymorphic structures. A selected example is devoted to how the monitoring of crystalline reactive carbon during methane dry reforming operation aids in the mechanistic understanding of a Ni/MnO catalyst. The most important aspect is the strict use of in situ monitoring of the structural changes occurring during (self-)activation to establish meaningful structure–property relationships allowing conclusions beyond isolated surface chemical aspects.

Microstructural characteristics and mechanical behaviour of aluminium matrix composites reinforced with Si-based refractory compounds derived from rice husk

The microstructural characteristics and mechanical behaviour of aluminium matrix composites reinforced with Si-based refractory compounds (SRC) derived from rice husk were investigated. The reinforcement materials (SRC) were synthesized using a carbothermal processing technique. The reinforcement was used to prepare a 10 wt.% Al-Mg-Si alloy-based composite using a double stir casting process. The composites produced were characterized using microhardness, tensile properties, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). From the results, A1650, C1650, and A1600 grades of the samples show more resistance to indentation due to the high proportion of hard SRC in the reinforced materials. Superior elongation values were observed for these composites A1650, C1650 and A1600 grades, respectively. The grades A1250, B1250, and C1250 series had the least toughness values within the range of 20–37% as compared to the control sample. For all composites under examination, the percent porosity was noted to be less than 4% and the strain to fracture was within 24–38%. Higher intensity of SiC was observed from the XRD spectrum and the formation of intermetallic materials. The tensile fracture surface morphologies of the composites produced were similar, showing a ductile dimple-like structure. The formation of a micro-crack and micro-void was also observed along the interphase.

Microstructure and Correlated Mechanical Properties Study of Ni-(Fe, Co)-Mn-(Al, In) as-Spun Ribbons

The Ni-Mn-based shape memory alloys as a promising candidate of elastocaloric material has been reported in many literatures, especially on bulk samples. The as-spun ribbon, which has a larger surface area and is more efficient for heat transfer, is rarely studied and hence of importance. In the present work, we succeeded in producing very long as-spun Ni-Fe-Mn-(Al, In) ribbons, with around 300 mm in length. The microstructure and mechanical properties of these as-spun ribbons were thoroughly investigated by scanning electron microscopy / electron backscattered diffraction (SEM/EBSD), nanoindentation and 3-points bending experiments. Through SEM/EBSD analyses, the microstructure and texture of the as-spun ribbons were studied. A gradient in microstructure exists along the thickness direction (TD) of the ribbon, which is induced by the temperature gradient during fast rate solidification, resulting in fine equiaxed grains along the surface contacted with the rotating wheel in melt spinning process and elongated grains, respectively. Both equiaxed and elongated grains possess a strong {001} fiber texture (<001>//TD). Nanoindentation analyses show little variation of hardness between the two different microstructures. The ductility index of both Ni-Fe-Mn-Al and Ni-Fe-Mn-In ribbons are within the range of intermetallic materials. The substitution of In by Al allows to increase very slightly the ductility index, which can reach 0.75. The fine equiaxed grains show better tensile resistance than the elongated grains in 3-points bending test. The substitution of In by Al improves the maximum bending strain by a factor of 3. The maximum strain for Ni-Fe-Mn-Al as-spun ribbons can reach 3 % before fracture. Fractography shows that the intergranular fracture is the main damage mechanism in these as-spun ribbons.

A New Method for Determining the Brittle-to-Ductile Transition Temperature of a TiAl Intermetallic

Intermetallic materials typically change their deformation behavior from brittle to ductile at a certain temperature called the Brittle-to-Ductile Transition Temperature (BDTT). This specific temperature can be determined by the Charpy impact, tensile or bending tests conducted at different temperatures and strain rates, which usually requires a large number of specimens. In order to reduce the number of necessary specimens for finding the BDTT, a new methodology comprising cyclic loadings as the crucial step was studied on a fully lamellar TiAl alloy with composition Ti-48Al-2Nb-0.7Cr-0.3Si. The loading blocks are applied isothermally under strain control and repeated on the same specimen at different temperatures. The development of plastic strain amplitude with increasing temperature is analyzed to determine the BDTT of the specimen. The BDTTs found with the described method agree well with literature data derived with conventional methods. With the loading strategy presented in this study, the BDTT and additionally the effect of strain rate on it can be found by using a single specimen.

TiAl-Based Materials by In Situ Selective Laser Melting of Ti/Al Reactive Composites

Additive manufacturing (AM) of refractory materials requires either a high laser power or the use of various easily melting binders. In this work, we propose an alternative—the use of spherical reactive Ti/Al composite particles, obtained by preliminary high-energy ball milling. These powders were used to produce high-temperature TiAl-based materials during the selective laser melting (SLM) process. When laser heating is applied, mechanically activated composite particles readily react with the release of a considerable amount of heat and transform into corresponding intermetallic compounds. The combustion can be initiated at relatively low temperatures, and the exothermic effect prevents the sharp cooling of as-sintered tracks. This approach allows one to produce dense intermetallic materials with a homogeneous structure in one step via SLM and eliminates the need for powerful lasers, binders, or additional post-processing and heat treatments.

Interfacial structure and strain accommodation in two-phase NbCo1.2Sn Heusler intermetallics

Multiphasic intermetallic materials are attractive candidates for functional applications where the constituent phases alone do not meet the property targets. The interfaces at the phase boundaries in these materials are central to their macroscopic properties, with the details of the atomic structure underpinning local thermomechanical, electrical, and magnetic behavior. Here, we characterize the interface structure in the biphasic Nb-Co-Sn system consisting of $\mathrm{Nb}{\mathrm{Co}}_{2}\mathrm{Sn}$ full Heusler (FH) precipitates embedded in a NbCoSn half Heusler (HH) matrix, which exhibits semicoherent interfaces with a 3.3% lattice parameter misfit that determines the constitution of the FH/HH interface on the nanometer scale. We use detailed transmission electron microscopy (TEM) and atomistic calculations to precisely determine the dislocation content and structure at the semicoherent interface, which modulates the strain fields in a semiregular pattern. We find that the interface forms regularly spaced paired partial dislocations with a joint Burgers vector of $a/2\ensuremath{\langle}110\ensuremath{\rangle}$, favored by misfit energy relief and chemical ordering. The interface exhibits numerous interface steps (disconnections) which in turn determine the precipitate morphology. Overall, the two phases show full coherency except in the vicinity of the misfit dislocation cores located every 11 nm, leading to a modulated strain field parallel to the interface, and no long-range strain fields as the interfacial dislocations accommodate the misfit strain.

Influence of Titanium-Containing Inoculants on the Structure of Metal in the Welds of High-Strength Low-Alloy Steels

We study the influence of titanium-containing refractory inoculants (nitrides, carbides, and intermetallic materials) on the structure of metal in the welds of high-strength low-alloy steels. The character of structural-and-phase transformations and the specific features of fine structures are determined by the method of transmission electronic microscopy with regard for the dislocation density distribution. The influence of structural components formed as a result of introduction of various types of inoculants on the mechanical properties of welded joints is investigated. The roles played by the structural factors (phase composition, subgrain structure, and the distribution of dislocations) in the behavior of local internal stresses and stress concentrators in the process of crack initiation are analyzed. For the case of welding of high-strength low-alloy steels, we determine the optimal compositions of applied inoculants guaranteeing the possibility of getting of high-quality and reliable welded joints with high mechanical characteristics and crack-growth resistance.

Half-Heusler Structures with Full-Heusler Counterparts: Machine-Learning Predictions and Experimental Validation

Heusler compounds form a diverse group of intermetallic materials encompassing many compositions and structures derived from cubic prototypes, and exhibiting complicated types of disorder phenomena...

Computationally directed discovery of bismuth-based binary intermetallic materials

Computationally directed discovery of bismuth-based binary intermetallic materials

Optimization of machining parameters in wire EDM of OFHC copper using Taguchi analysis

WEDM may endure a one among the non-traditional machining processes used for machining advanced form parts and onerous materials like composites and inter-metallic materials. This paper emphasizes the study of unique variance in optimal solutions likely, metal removal rate and surface roughness based on the process parameters of wire electric arc machining in OFHC copper machining. Mathematical models are progressively developed for metal removal rates and surface roughness mistreatment Taguchi constant styles (L9) and consequently opted for improvement in objective functions. In key addition, the logistic regression equations were developed jointly between the process variables because the constant impact on metal removal rates and surface roughness are merely opposite, potential downside is adequately considered as a multi-objective improvement problem. The solutions obtained therefore may be utilized as machining recommendations to line levels of method parameters to satisfy the set of said method yield criteria. Over here, results indicate precisely that pulse on time is the most vital issue influencing the MRR and Ra followed by pulse off time and wire tension.

Interplay of Magnetism and Topological Superconductivity in Bilayer Kagome Metals.

The binary intermetallic materials, M_{3}Sn_{2} (M=3d transition metal) present a new class of strongly correlated systems that naturally allows for the interplay of magnetism and metallicity. Using first principles calculations we confirm that bulk Fe_{3}Sn_{2} is a ferromagnetic metal, and show that M=Ni and Cu are paramagnetic metals with nontrivial band structures. Focusing on Fe_{3}Sn_{2} to understand the effect of enhanced correlations in an experimentally relevant atomistically thin single kagome bilayer, our abinitio results show that dimensional confinement naturally exposes the flatness of band structure associated with the bilayer kagome geometry in a resultant ferromagnetic Chern metal. We use a multistage minimal modeling of the magnetic bands progressively closer to the Fermi energy. This effectively captures the physics of the Chern metal with a nonzero anomalous Hall response over a material relevant parameter regime along with a possible superconducting instability of the spin-polarized band resulting in a topological superconductor.