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We review topological approaches to the analysis of crystal structures of intermetallic compounds and to searching for structural relations between them as the relations between their underlying atomic nets. We introduce the concept of skeletal net to find the simplest system of interatomic contacts in intermetallic compounds, which supports the three-periodic crystal architecture. Using the observed approaches, we have revealed topological relations between crystal structures of binary MeX compounds (Me = Re, Ti or Rh; X = B, C, N, or Si) and found a key role of the body-centered cubic net in their topological hierarchy. We have explored the configuration space of the corresponding crystalline systems by generating all possible 'subnet-supernet' topological transformations, optimized the resulting topological motifs with DFT methods and found a new phase of RhB to be stable above 22 GPa. We discuss the role of topological representations in the prediction of new crystalline chemical substances. [ABSTRACT FROM AUTHOR]

The CeCr2Al20-type aluminides RETi2Al20 (RE = Eu, Gd, Tb, Dy and Yb), space group F d 3 ‾ m $Fd\overline{3}m$ , show the formation of solid solutions RETi2Al20−xGa x with gallium in the ranges 0 ≤ x ≤ 10. Polycrystalline samples were prepared from the elements in alumina crucibles or directly via arc-melting followed by annealing in order to increase crystallinity. The structures of six single crystals were refined from single crystal X-ray diffractometer data for determining the precise occupancy parameters of the aluminum and gallium atoms. The solubility limit of gallium was found at around x ≈ 10. The RETi2Al20−xGa x structures show a MgCu2-related substructure of the rare earth and titanium atoms. The Al/Ga atoms then form Frank-Kasper type polyhedra around the RE and Ti atoms, i. e., RE@(Al/Ga)16 and Ti@(Al/Ga12). These are the basic building units of the RETi2Al20−xGa x structures. Temperature-dependent magnetic susceptibility studies show Pauli paramagnetic behavior for the YbTi2Al10Ga10 sample, i. e., a stable divalent ytterbium ground state. [ABSTRACT FROM AUTHOR]

The intermetallic compounds Eu4PdMg and Ca4PdMg form a complete solid solution Eu4–xCa x PdMg. Further phase analytical studies showed that Eu4PdMg does not allow substitution with strontium. The polycrystalline Eu4–xCa x PdMg samples were characterized by powder X-ray diffraction. The structure of Eu2.233(6)Ca1.767PdMg was refined from single crystal X-ray diffractometer data: Gd4RhIn type, F 4 ‾ 3m, a = 1,475.42(10) pm, wR2 = 0.0476, 674 F2 values, 23 variables. Temperature dependent magnetic susceptibility measurements show a drastic decrease of the Curie temperature with increasing calcium substitution. 151Eu Mössbauer spectra of Eu4PdMg and Eu2Ca2PdMg confirm the divalent ground state of europium. [ABSTRACT FROM AUTHOR]

The stannides SrPdSn (TiNiSi type, orthorhombic space group Pnma) and m-BaPtSn (EuNiGe type, monoclinic space group P21/c) were synthesized from the elements in sealed tantalum ampoules in a high-frequency furnace. Their structures were refined from single-crystal X-ray diffraction data. SrPdSn crystallizes directly from the melt and is stable upon annealing at T = 1073 K. A BaPtSn sample quenched from the melt adopts the cubic LaIrSi-type structure, cubic space group P213 (c-BaPtSn) and shows a temperature induced (annealing at 1070 K) structural phase transition leading to a EuNiGe-type low-temperature modification m-BaPtSn. The phase transition leads to a reconstruction within the polyanionic [PtSn] δ− network. The latter is three-dimensional and composed of ten-membered Pt5Sn5 rings in c-BaPtSn, while the polyanion is two-dimensional in m-BaPtSn and is composed of condensed Pt4Sn4 and Pt2Sn2 rings. The two-dimensional substructure leads to a strong moisture sensitivity for m-BaPtSn. The Pt–Sn distances in both modifications range from 257 to 267 pm, indicating substantial covalent bonding. [ABSTRACT FROM AUTHOR]

Effect of load ratio (R) on the interface microstructure and phase stability was investigated in mild steel/Grade-2 Ti explosive clads using experimental and JMatPro® computations. At low-impact-energy conditions (i.e., R = 1.07), the interface exhibited a symmetrical wavy morphology with molten metal entrapped in isolated regions within the vortices of the waves, while at high-impact loading conditions (R = 3) the interface had complex weld solidification structure consisting of planar interface, columnar and equiaxed dendrites. Based on the study, it was concluded that under high-impact loading conditions, the interface microstructure of the explosive clads will resemble fusion welded joints, but with relatively lower thickness of the interaction zones. [ABSTRACT FROM AUTHOR]

The challenges in the fuel cell industry lie in the cost, performance, and durability of the electrode components, especially the platinum‐based catalysts. Alloying has been identified as an effective strategy to reduce the cost of the catalyst and increase its efficiency and durability. So far, most studies focused on the design of PtM bimetallic nanocatalyst, where M is a transition metal. The resulting PtM materials show higher catalytic activity, but their stability remained challenging. In addition, most of the transition metals M are expensive or low abundant. Tin (Sn) has gained attention as alloying element due to its versatility in manufacturing both anode and cathode electrodes. If used as anode catalyst, it is able to overcome poisoning from CO and related intermediates. As cathode catalyst, it improves the kinetics of the oxygen reduction reaction (ORR). Additionally, Sn is an abundant and cheap element. The current contribution outlines the state of the art on the alloy and shape effect on PtSn activity and stability, demonstrating its high potential to develop cheaper, more efficient and durable catalysts for fuel‐cell electrodes. Additionally, in situ analytical and spectroscopic studies can shed light on the elementary steps involved in the use of PtSn catalytic systems. Finally, this intriguing material can be used as a parent system for the synthesis of high‐entropy‐alloys and intermetallics materials. [ABSTRACT FROM AUTHOR]

Pt‐based intermetallics are regarded as highly efficient electrocatalysts for oxygen reduction reaction (ORR). However, Pt‐based intermetallics with different Pt: M atomic ratios have different atomic arrangements and crystal structures, which will change the electronic structure and coordination environment of Pt, thus affecting the electrocatalytic activity. In this work, we prepared L12‐Pt3Co and L10‐PtCo intermetallic catalysts by modulating the molar ratio of Pt and Co precursors using a thermal annealing method. The mass activity (MA) of L10‐PtCo is 0.52 A mg−1Pt at 0.9 V, which is 1.44 times larger than that of L12‐Pt3Co (0.36 A mg−1Pt). In addition, the MA of L10‐PtCo decreases by 17.31 % after 10,000 CV cycles, which is smaller than that of L12‐Pt3Co (25.00 % loss in MA), showing excellent structural stability. Theoretical calculations reveal that compared to L12‐Pt3Co, L10‐PtCo has more electrons transferred to the Pt sites, which further optimizes the electronic structure of Pt and reduces the d‐band center, leading to the increase of the electrocatalytic performance. This work provides new insights into the study of Pt‐based intermetallics with different Pt: M ratios, which is helpful for the screening and preparation of high‐performance Pt‐based intermetallics. [ABSTRACT FROM AUTHOR]

The stannides Sr3Rh4Sn4 and Sr2.43Eu0.57Ir4Sn4 (Na3Pt4Ge4-type, space group I 4 ‾ 3m) were synthesized by induction-melting of the elements in sealed tantalum tubes followed by an annealing sequence to increase the crystallinity. Their polycrystalline samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data. The basic building units are [Rh4Sn4] respectively [Ir4Sn4] stellae quadrangulae which condense to rigid three-dimensional networks. A striking crystal chemical feature of the Na3Pt4Ge4-type phases are pronounced anisotropic displacements of the divalent cations. Additional structure refinements of Sr3Rh4Sn4 and Sr2.43Eu0.57Ir4Sn4 and the previously reported stannide Sr3Ir4Sn4 at 90 K reveal less anisotropic behavior in going to lower temperatures. [ABSTRACT FROM AUTHOR]

The stannides Sr3Rh4Sn4 and Sr2.43Eu0.57Ir4Sn4 (Na3Pt4Ge4-type, space group I 4 ‾ 3m) were synthesized by induction-melting of the elements in sealed tantalum tubes followed by an annealing sequence to increase the crystallinity. Their polycrystalline samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data. The basic building units are [Rh4Sn4] respectively [Ir4Sn4] stellae quadrangulae which condense to rigid three-dimensional networks. A striking crystal chemical feature of the Na3Pt4Ge4-type phases are pronounced anisotropic displacements of the divalent cations. Additional structure refinements of Sr3Rh4Sn4 and Sr2.43Eu0.57Ir4Sn4 and the previously reported stannide Sr3Ir4Sn4 at 90 K reveal less anisotropic behavior in going to lower temperatures. [ABSTRACT FROM AUTHOR]

In this work, AZ31 and AZ31-1 wt.% RE (RE = Nd, Dy, Nd+Dy) alloys were prepared by conventional casting. The effect of single and co-addition of rare earth (RE) on the microstructure, mechanical properties and corrosion behavior of as-cast AZ31 magnesium alloys were investigated at ambient temperature, and after heat treatment at 400 °C for 1 h. The addition of 1 wt.% RE (RE = Nd, Dy, Nd+Dy) preferentially formed the Al2RE phase and completely suppressed the formation of the intermetallic β-Mg17Al12 phase. An excellent ultimate tensile strength (UTS)/ductility combination of 209 MPa/21% and 192 MPa/17% with an adequate yield strength (YS) of 90 MPa was observed for AZ31+Nd sample in as-cast and annealed states, respectively. The work-hardening rate of the AZ31 alloy containing Nd and Dy increased significantly after annealing compared to those of the as-cast state. Fracture analysis indicated that the additive RE did not obviously change the fracture mechanism of the Mg alloy. All specimens exhibit a hybrid fracture with cleavages and dimples. The weight loss test showed that the corrosion resistance of the AZ31 Mg alloy was improved with added RE as it interacts with Al to form Al-RE phase, which upgraded the corrosion resistance of the alloys. The co-addition of RE (RE = Nd+Dy) was proven to enhance corrosion resistance, and also stabilized the corrosion rate. In brief, the co-addition of Nd and Dy significantly improved the corrosion resistance of the AZ31 magnesium alloys than the counterpart of the mechanical properties. [ABSTRACT FROM AUTHOR]

The eutectoid Ti–Cu alloy has the advantages of high strength and hardness. However, the pearlite eutectoid structures with coupled α + Ti2Cu lamellae result in low plasticity. In this study, a Zr alloying method is proposed to suppress the formation of lamellar pearlite and promote a bainite-like morphology. Increasing the Zr content can transform the α lamellae into rod-like laths and the Ti2Cu lamellae into dispersed particles, thereby reducing their embrittlement effect. The α laths are further refined to about 0.27 and 0.37 μm with 30% and 50% Zr addition, resulting in strong grain boundary strengthening effects. As a result, the mechanical properties are enhanced after Zr alloying. The best combination of compressive yield strength, maximum strength, and plasticity is achieved with 30% Zr addition, which is about 1040 MPa, 2505 MPa, and 33%, respectively. The results in this study can offer valuable insights into microstructure optimization and performance enhancement in active eutectoid Ti–Cu systems.

In this work, anisotropic fatigue crack growth rate (FCGR) behaviour in a hot-rolled Mg-3wt%Al-0.5wt%Ce alloy was investigated using compact tension (CT) specimens with notch (an) parallel to the rolling direction (RD) and transverse direction (TD). The FCGR tests were conducted at a constant load ratio (R = 0.1) and maximum stress intensity factor (KMax = 15.6 MPa√m) to investigate the crack closure effect. For both constant R and KMax conditions: (i) the load-displacement curves for every loading cycle were linear for an ∥ to RD and TD, indicating no crack closure; (ii) the FCGR was found to be lower for an ∥ RD than an ∥ TD over the entire stress intensity factor range (ΔK). The hot-rolled sample contained long-aligned Al11Ce3 intermetallic phase within grain boundaries that are elongated along RD. During the FCGR test, {101¯2}〈101¯1〉 extension twins (ET) with lamellae ∼⊥ and c-axis ∼∥ to these elongated intermetallics along RD developed irrespective of the notch orientation. During the loading cycle, these intermetallics along RD generate back-stresses, reducing the in-plane tensile stress ∼∥ and ∼⊥ to crack-tip to ∼0 for an ∥ to RD and TD, respectively. Hence, lenticular ET ∼⊥ and ∼∥, with c-axis ∼∥ and ∼⊥ to crack path activates, leading to trans and inter lamellar crack for an ∥ to RD and TD, respectively, and anisotropic FCGR. Translamellar crack in an ∥ RD reduces the FCGR due to plastic energy dissipation as perceived by comparatively more geometrically necessary boundaries (GNBs). On the other hand, faster FCGR was obtained for an ∥ TD due to interlamellar cracking. Thus, the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility. The Fractography for an ∥ RD shows smaller elongated grooves along crack propagation, which indicates crack arrest. However, larger elongated grooves for an ∥ TD indicated easy crack propagation due to favourable interlamellar crack.

Well-shaped single crystals of Ta11Pt4 formed through crucible attack during phase analytical studies in the Ca–Pt–Zn system. Phase-pure Ta11Pt4 was subsequently obtained from the pure elements by arc-melting. The crystal structure of Ta11Pt4 was refined from single crystal X-ray diffractometer data: P42/mnm, a = 992.94(8), c = 516.59(4) pm, wR2 = 0.0672, 576 F2 values and 27 variables. Ta11Pt4 is a new coloring variant in the large family of sigma phase compounds. Of the five crystallographically independent sites, four are occupied by tantalum and the fifth one by platinum in a fully ordered manner. The platinum atoms have distorted icosahedral coordination by 11 tantalum and 1 platinum atom. Two of these Ta@Ta11Pt icosahedra are condensed by interpenetration forming a Pt2 pair with 275 pm Pt–Pt distance. These double-icosahedra are the monomeric building unit of the Ta11Pt4 structure and further condense via common edges to a three-dimensional dense sphere packing. The Ta–Ta distances cover a broader range from 256 to 329 pm, comparable to the structure of bcc tantalum. Temperature dependent magnetic susceptibility studies indicate Pauli paramagnetism. [ABSTRACT FROM AUTHOR]

Single crystals of CaAl2Pt2, Ca2Al3Pt and Ca2AlPt2 were initially observed in an attempt to synthesize Ca3Al4Pt4. Their structures were determined using single‐crystal X‐ray diffraction experiments. While nominal CaAl2Pt2 (CaBe2Ge2 type, P4/nmm, a=426.79(2), c=988.79(6) pm, wR2=0.0679, 246 F2 values and 18 variables) and Ca2Al3Pt (Mg2Cu3Si type, P63/mmc, a=561.46(5), c=876.94(8) pm, wR2=0.0664, 214 F2 values and 13 variables) exhibit Al/Pt mixing, for Ca2AlPt2 (Ca2Ir2Si type, C2/c, a=981.03(2) b=573.74(1), c=772.95(2) pm, β=101.862(1)° wR2=0.0307, 2246 F2 values and 25 variables) no mixing was observed. Subsequently, the nominal compositions were targeted with synthetic attempts from the elements using arc‐melting and annealing techniques. For CaAl2Pt2 and Ca2Al3Pt always multi‐phase mixtures were observed while Ca2AlPt2 could be obtained as almost X‐ray pure material. Quantum‐chemical calculations were used to investigate the charge transfer in these compounds rendering them polar intermetallics with a designated [AlxPty]δ− polyanion and Caδ+ cations in the cavities of the polyanions. [ABSTRACT FROM AUTHOR]

NiAl intermetallic-based hardfacing coatings were processed by in situ synthesis from elemental Ni and Al powders mixtures, by Directed Energy Deposition - Plasma Transferred Arc (DED-PTA). The exothermic nature of NiAl synthesis promotes the formation of columnar grains, which do not contribute to mitigate the low toughness of the material at room temperature, limiting its use. Refining the microstructure is a path to overcome this limitation and the approach used took advantage of tungsten carbide nanoparticles (WC-NPs) to limit grain growth during solidification. During preparation of powder mixtures, the adhesion of 1 wt.%WC-NPs to the surface of Ni particles (which act as carriers) helps to reduce the tendency to agglomeration. However, this approach proved to be ineffective for the in situ synthesis of NiAl, since the NPs form a film of molten material on the Ni particle surface as they cross the plasma arc, limiting the interdiffusion of Ni and Al, compromising the synthesis of the aluminide alloy. The present study assessed this challenge by investigating the amount of NP carriers, i.e, the proportion of Ni particles that carry the NPs, that allows both for the synthesis of NiAl, and grain refining due to the WC-NPs. Results show that β-NiAl phase was successfully formed in multi-layer coatings, processed in situ by DED-PTA. Powder mixtures containing 50% and 70% NP carriers promoted a progressive reduction in grain size by the addition of 1 wt.% WC-NPs in the Ni+Al powder mixture, followed by an increase in hardness. [ABSTRACT FROM AUTHOR]

Single crystals of Ca2Co5.66Zn11.34, Ca2Co4.62Zn12.38 and Ca2Co2.36Zn14.64 were obtained from reactions of the elements in sealed tantalum ampoules. The crystal structures were refined from single-crystal X-ray diffractometer data: Th2Zn17 type, R 3 ‾ m, a = 879.93(7), c = 1282.81(11) pm, wR = 0.0394, 432 F2 values, 25 variables for Ca2Co5.66Zn11.34, a = 886.0(4), c = 1293.1(6) pm, wR = 492 F2 values, 25 variables for Ca2Co4.62Zn12.38 and a = 894.62(16), c = 1307.2(3) pm, wR = 0.0463, 460 F2 values, 24 variables for Ca2Co2.36Zn14.64. The crystal chemistry of these phases is driven by different Co/Zn mixed occupied sites. The structures are explained as a rod packing of infinite strands that are built up from pairs of interpenetrating Ca@(Co/Zn)19 and Zn1@(Co/Zn)13Ca polyhedra. [ABSTRACT FROM AUTHOR]

Within the series of the equiatomic REAlRh compounds, the representatives with RE = Y, La–Nd, Gd, Ho, Tm and Yb have been synthesized. The members with RE = Sm, Tb, Dy, Er and Lu, however, had not yet been reported. They have now been synthesized and structurally as well as magnetically and NMR-spectroscopically characterized. All members crystallize isostructurally in the orthorhombic TiNiSi type, similar to most of the known analogues. The evolution of their unit cell volumes exhibits the expected decrease due to the lanthanide contraction. While LuAlRh shows Pauli-paramagnetic behavior, SmAlRh, TbAlRh, DyAlRh, ErAlRh, and TmAlRh exhibit antiferromagnetic ground states with Néel temperatures between TN = 45 and 4 K. 27Al MAS-NMR investigations have been conducted on YAlRh and LuAlRh. The results of quantum-chemical calculations support the conclusions drawn from the NMR-spectroscopic study and give information on the charge distribution in these intermetallic aluminum metallides. [ABSTRACT FROM AUTHOR]

The main motivation for this study was to improve implant materials. The influence of silver and gold on the structure and mechanical properties of Mg–Nd–Zr alloy was studied. In the work, quantitative and qualitative evaluation of the structural components of magnesium alloy with noble metal additives was performed. The research methods used were investigation of the mechanical properties and observation of micro– and macrostructures. The results showed that modification of magnesium alloy with Ag and Au contributes to the formation of spherical intermetallics of smaller size groups, which become additional centers of crystallization and grind the cast structure. The best composition from additional alloying with silver and gold was determined. Their positive effect on the strength and ductility properties of the metal was established. Preclinical and clinical testing was performed and the prospects for noble metal modification of bioabsorbable magnesium alloy for implant production usage were shown. [ABSTRACT FROM AUTHOR]

Within this study, the alloy NiAl–2.5Ta–7.5Cr is investigated as a new matrix material for cBN-reinforced abrasive turbine blade tip coatings as currently used NiCoCrAlY matrix alloys suffer from insufficient strength at the high operating temperatures. Laser-based directed energy deposition with blown powder was applied to produce cBN reinforced NiAl-based coatings on monocrystalline CMSX-4 substrates. For this, powdery titanium-coated cBN and NiAl–2.5Ta–7.5Cr material were co-injected into the process zone to achieve an in situ formation of a NiAl–2.5Ta–7.5Cr/cBN composite. In order to overcome challenges such as cracking susceptibility, inductive preheating of the substrate up to 800 °C was used. Optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, as well as electron backscatter diffraction were applied to analyse the fabricated samples' microstructure. Additionally, the mechanical properties were evaluated by means of microhardness mappings. This work demonstrates the feasibility of in situ forming a metal matrix composite with a homogeneous distribution of cBN particles. The results show the beneficial effect of high-temperature preheating on the crack formation. However, the study also reveals challenges such as cracking induced by the injected cBN particles as well as severe intermixing of substrate and coating, which yields spatially resolved deviations in the chemical composition and resulting variations in microstructure and hardness. [ABSTRACT FROM AUTHOR]

Binary alloys of platinum (Pt) are well‐studied to address the poor poisoning resistance of Pt. Among them, the ordered alloys, also known as intermetallics, tend to show exceptional advantages in activity and durability. In contrast, the medium and high‐entropy Pt alloy systems, with three or more elements, have been reported with better performance but not fully understood, due to the complex relationship of elemental miscibility. Herein a unique asymmetric synergistic effect in the ordering process of a series of ternary alloy AuxPt1‐xCu3 (x = 0‐1) is reported. The volcano plot of ordering degree (OD) in AuxPt1‐xCu3 (x = 0‐1) shows its peak in the Au‐rich samples but gradually shifts to Au/Pt equal molar ratio with the increasing temperature. Based on formation energy calculation and molecular dynamics analysis, the unique ordering trend of ternary alloys and the shift of OD peak position are rationalized. Among the studied samples, Au0.4Pt0.6Cu3‐350 sample exhibits the highest mass activity in electrocatalytic ethanol oxidation (3.58 A·mgAu+Pt−1), 4.4 times higher than that of commercial Pt/C. This work not only explores the unique asymmetrical effect in the OD of ternary intermetallics, but also helps to understand the complex inter‐metallic relationship in the medium‐entropy and high‐entropy alloys. [ABSTRACT FROM AUTHOR]

The zinc-rich intermetallic phases CaRu2Zn10, SrRu2Zn10 and EuRu2Zn10 were synthesized by induction-melting of the elements in sealed tantalum ampoules followed by annealing to increase the crystallinity. The samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data: new type, P42/nnm, a = 894.68(14), c = 518.44(9) pm, wR2 = 0.0830, 432 F2 values, 22 variables for CaRu2Zn10, a = 907.01(10), c = 516.35(6), wR2 = 0.0469, 445 F2 values, 22 variables for SrRu2Zn10 and a = 902.84(9), c = 515.91(5) pm, wR2 = 0.0469, 434 F2 values, 22 variables for EuRu2Zn10. The three structures are new ordering variants of the aristotype ThMn12. They are discussed on the basis of a group-subgroup scheme and compared to the known superstructures CaCr2Al10, ErNi10Si2 and ScFe6Ga6. The calcium atoms within the Ca@Ru4Zn16 polyhedra have flattened tetrahedral ruthenium coordination, reducing the calcium site symmetry to 4 ‾ 2m (instead of 4/mmm in the aristotype). Electronic structure calculations show a substantial charge transfer from calcium to ruthenium and an almost neutral zinc substructure. [ABSTRACT FROM AUTHOR]

Liquid metal nanodroplets are an emerging class of underexplored materials with significant potential in many applications, including catalysis, bio‐therapeutics, and phase‐change materials. These nanostructures are generally synthesized by mechanical agitation via ultrasonication of low‐melting metals like Ga. Once these materials are successfully synthesized, they can be suspended in a vast array of different solvents. However, one major issue arises specifically with liquid metal alloys which are found to de‐alloy in the sonication process. Here, it is demonstrated that this challenge can be overcome by undertaking sonication at high temperatures, suspending nanodroplets within molten sodium acetate (NaOAc). After cooling, the nanostructures become planet‐like nanodroplets which are covered by an interfacial oxide crust, feature a liquid metal mantle, and a solid core. The molten salt solvent can effectively be removed rendering this approach to be ideal, especially for catalysts. The proof‐of‐concept application is demonstrated by carrying out electrocatalytic ethanol oxidation, using the Cu–Ga system. The superior performance of the Cu–Ga nanodroplets highlights potential in catalyzing a vast array of reactions. Aside from the Cu–Ga system, this facile process can be applied to multiple other systems, including Ag–Ga, Zn–Ga, Bi–Ga, In–Cu, and Sn–Cu. [ABSTRACT FROM AUTHOR]

In this study, a bulk-area stirring zone (BSZ) was generated within the Al–Mg–Si alloy using friction stir processing with a combination of pin overlapping and water cooling. Detailed examinations were conducted on various aspects, including microstructural evolution, intermetallic behavior, crystallographic texture, and mechanical properties. The bulk-area stir zone (BSZ) microstructure contains an equiaxed fine-grained structure with more fraction of high-angle grain boundaries due to intense plastic straining and dynamic recrystallization. The grain refinement remained consistent across each overlapping pass, typically within the range of 3 to 4 µm. Notably, the BSZ exhibited the formation of A1-{111}(112) texture components with a maximum intensity of 5.4 owing to the material flow caused by the tool's revoluting nature around the pin. The hardness distribution across the BSZ was found to be uniform and aligned with the grain size values. The combined effects of material softening and intermetallic dissolution in the BSZ led to a substantial enhancement of 127% in ductility. [ABSTRACT FROM AUTHOR]

Previously conducted studies determined that the reactive sintering of B 4 C and stoichiometric additions of TiSi 2 or Ti 5 Si 3 intermetallics created a dense TiB 2 -SiC double-phase system that could be classified as ultra-high temperature ceramics (UHTC). In this work, a spark plasma sintering (SPS) technique was used to improve the sintering process and thus further reduce the obtaining temperature and improve the final microstructure and mechanical properties of the proposed, double-phase TiB 2 -SiC UHTC systems. To evaluate the effects of the experiment, a comprehensive study of phase composition, microstructure and mechanical properties was added. As a result, minimal sintering temperatures were further reduced from 1420 - 1650 ºC to a range of 1200–1400 ºC. Among the prepared composites those sintered at 1400 ºC achieved the best properties. The prepared composites maintained high hardness (up to 24.85 GPa), high tensile strength (up to 309 GPa), relatively high fracture toughness (up to 4.80 MPa∙m1/2) and relatively low density, all of which characterized TiB 2 -SiC UHTC systems. [ABSTRACT FROM AUTHOR]

The zinc-rich intermetallic phases CaRu2Zn10, SrRu2Zn10 and EuRu2Zn10 were synthesized by induction-melting of the elements in sealed tantalum ampoules followed by annealing to increase the crystallinity. The samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data: new type, P42/nnm, a = 894.68(14), c = 518.44(9) pm, wR2 = 0.0830, 432 F2 values, 22 variables for CaRu2Zn10, a = 907.01(10), c = 516.35(6), wR2 = 0.0469, 445 F2 values, 22 variables for SrRu2Zn10 and a = 902.84(9), c = 515.91(5) pm, wR2 = 0.0469, 434 F2 values, 22 variables for EuRu2Zn10. The three structures are new ordering variants of the aristotype ThMn12. They are discussed on the basis of a group-subgroup scheme and compared to the known superstructures CaCr2Al10, ErNi10Si2 and ScFe6Ga6. The calcium atoms within the Ca@Ru4Zn16 polyhedra have flattened tetrahedral ruthenium coordination, reducing the calcium site symmetry to 4 ‾ 2m (instead of 4/mmm in the aristotype). Electronic structure calculations show a substantial charge transfer from calcium to ruthenium and an almost neutral zinc substructure. [ABSTRACT FROM AUTHOR]

Direct catalytic conversion of CO2 to methanol via renewable hydrogen has emerged as a promising technology among the various CO2 conversion techniques. However, efficient hydrogenation of CO2 using conventional Cu‐ZnO‐based catalysts, which are currently used for industrial methanol production from synthesis gas, remains a challenge due to inefficient energy conversion, poor stability and sluggish CO2 conversion kinetics. As the catalytic activity, stability and methanol selectivity of conventional Cu/ZnO catalysts are still insufficient for industrial applications, novel catalyst formulations using transition metals/metal oxides and supported noble metal nanostructures have emerged. Among them, intermetallic compounds are being explored for their unique electronic and crystalline structures, which can be tailored by controlled, precise, and seamless tuning of interatomic distances, specific arrangements and electronic structure to enhance their stability and activity for the selective hydrogenation of CO2 to methanol. In this context, intermetallic catalysts containing Pd, Cu and Ni combined with metal oxide nanoparticles (ZnO, Ga2O3, In2O3, etc.) have been shown to be more effective than the classical Cu‐ZnO‐Al2O3. This review analyses the progress made in the study of these intermetallic catalysts by analysing different aspects of their preparation, characterization, effects of promoters, support interactions, etc. Future research perspectives are discussed in the context of potential industrial applications of intermetallics for direct methanol production via CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

Al–Zn–Mg–Si alloy coatings have been developed to inhibit the corrosion of cold-rolled steel sheets by offering galvanic and barrier protection to the substrate steel. It is known that Fe deposited from the steel strip modifies the microstructure of the alloy. We cast samples of Al–Zn–Mg–Si coating alloys containing 0.4 wt% Fe and directionally solidified them using a Bridgman furnace to quantify the effect of this Fe addition between 600   ° C and 240   ° C . By applying a temperature gradient, growth is encouraged, and by then quenching the sample in coolant, the microstructure may be frozen. These samples were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine the morphological effects of the Fe distribution across the experimental temperature range. However, due to the sub 1 wt% concentration of Fe, synchrotron X-ray fluorescence microscopy (XFM) was applied to quantitatively confirm the Fe distribution. Directionally solidified samples were scanned at 7.05 keV and 18.5 keV using X-ray fluorescence at the Australian Synchrotron using the Maia array detector. It was found that a mass nucleation event of the Fe-based τ6 phase occurred at 495   ° C following the nucleation of the primary α-Al phase as a result of a peritectic reaction with remaining liquid. [ABSTRACT FROM AUTHOR]

Various physical properties of the ternary intermetallics CeTAl3 (T = Pd, Pt, Cu, Ag and Au) are investigated in tetragonal phase with space group I4 mm (No. 107) using generalized gradient approximation (GGA) along with Hubbard potential (U) in the domain of density functional theory (DFT). The calculated results show that the understudy intermetallics are stable in tetragonal symmetry and are found in good agreement with experiments. Magnetic optimization energies show that CePdAl3 is stable in G-type antiferromagnetic (G-AFM) phase, CeTAl3 (T = Cu and Au) are stable in A-AFM, CePtAl3 is spin glass (SG) and CeAgAl3 is stable in ferromagnetic (FM) phase and are confirmed through magnetic susceptibilities. The electronic band profiles, electrical resistivities and electronic thermal conductivities demonstrated the metallic nature of these intermetallics and CePtAl3 is good conductor among this series. The elastic properties show that all these intermetallics are mechanically stable, anisotropic and brittle in nature. The above mention properties make these intermetallics suitable for spintronics, storage and electronic devices. [ABSTRACT FROM AUTHOR]

Samples of the solid solution Gd2–xYxCu2Mg (in steps of x = 0.2) were synthesized from the elements in sealed tantalum ampoules in a high-frequency furnace. The polycrystalline samples were characterized by X-ray powder diffraction. The structure of Gd0.988(6)Y1.012(6)Cu2Mg was refined from single-crystal X-ray diffractometer data: Mo2B2Fe type, P4/mbm, a = 762.83(4), c = 375.48(2) pm, wR2 = 0.0277, 285 F2 values and 13 variables. Single-crystal data gave no hint for Gd/Y ordering. All samples behave like Curie-Weiss paramagnets with stable trivalent gadolinium and ferromagnetic ordering at low temperature. Within the solid solution the Curie temperature drops almost linearly from TC = 113.5(1) K for Gd2Cu2Mg to 9.3(1) K for Gd0.2Y1.8Cu2Mg, allowing a precise adjustment of the magnetic ordering temperature through gadolinium spin dilution. [ABSTRACT FROM AUTHOR]

• Hot-rolled Mg-3Al-0.5Ce alloy shows anisotropic fatigue crack growth rate (FCGR) behavior. • Anisotropic FCGR could be due to long-aligned Al 11 Ce 3 intermetallics within the elongated grain boundaries ∼ ∥ RD. • Due to Al 11 Ce 3 intermetallics ∼ ∥ RD, { 10 1 ¯ 2 } 〈 10 1 ¯ 1 〉 extension twin (ET) lamellae form ∼⊥ to RD for the notch (a n)∥ RD and TD. • The ET lamellae ⊥ and ∥ the crack path lead to trans and inter lamellar cracks with low and high FCGR for a n ∥ RD and TD. • No crack closures were observed during FCGR tests with a n ∥ RD and TD for constant R and K Max conditions. In this work, anisotropic fatigue crack growth rate (FCGR) behaviour in a hot-rolled Mg-3wt%Al-0.5wt%Ce alloy was investigated using compact tension (CT) specimens with notch (a n) parallel to the rolling direction (RD) and transverse direction (TD). The FCGR tests were conducted at a constant load ratio (R = 0.1) and maximum stress intensity factor (K Max = 15.6 MPa√ m) to investigate the crack closure effect. For both constant R and K Max conditions: (i) the load-displacement curves for every loading cycle were linear for a n ∥ to RD and TD, indicating no crack closure; (ii) the FCGR was found to be lower for a n ∥ RD than a n ∥ TD over the entire stress intensity factor range (Δ K). The hot-rolled sample contained long-aligned Al 11 Ce 3 intermetallic phase within grain boundaries that are elongated along RD. During the FCGR test, { 10 1 ¯ 2 } 〈 10 1 ¯ 1 〉 extension twins (ET) with lamellae ∼⊥ and c-axis ∼ ∥ to these elongated intermetallics along RD developed irrespective of the notch orientation. During the loading cycle, these intermetallics along RD generate back-stresses, reducing the in-plane tensile stress ∼ ∥ and ∼ ⊥ to crack-tip to ∼ 0 for a n ∥ to RD and TD, respectively. Hence, lenticular ET ∼ ⊥ and ∼ ∥ , with c-axis ∼ ∥ and ∼ ⊥ to crack path activates, leading to trans and inter lamellar crack for a n ∥ to RD and TD, respectively, and anisotropic FCGR. Translamellar crack in a n ∥ RD reduces the FCGR due to plastic energy dissipation as perceived by comparatively more geometrically necessary boundaries (GNBs). On the other hand, faster FCGR was obtained for a n ∥ TD due to interlamellar cracking. Thus, the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility. The Fractography for a n ∥ RD shows smaller elongated grooves along crack propagation, which indicates crack arrest. However, larger elongated grooves for a n ∥ TD indicated easy crack propagation due to favourable interlamellar crack. [Display omitted] [ABSTRACT FROM AUTHOR]

Al and its alloys have a wide range of applications thanks to their low density, cost, and superior specific strength. Especially Al–Cu matrix composites are promising alloys with superior microstructural and mechanical performance characteristics. Thanks to the formation of the intermetallic due to the contained Cu, they significantly improve the properties of their Al-based alloys. In this study, pure aluminum–Cu matrix composites reinforced mainly with ceramic microparticles based on SiC carbide and ZrO2 oxide were fabricated by powder metallurgy. Three different values were determined for the Al–Cu content of the compositions, and these were produced in tube furnaces at 380 and 580°C for 4 h under an inert atmosphere using liquid phase sintering. According to the data of SEM and EDS analyses, microstructures formed in all samples were homogeneous. It was found that increasing sintering temperature increased microstructural densification. Adding mainly Cu and ceramic reinforcements to the microstructure significantly improved the hardness up to 2.05 times. Due to their intermetallic formation, the highest hardness values were determined in the samples containing high amounts of Cu, such as 173.73 HV. In the wear tests, it was observed that the samples sintered at high temperatures showed superior tribological performance characteristics. Also, the high Cu content improved the samples' friction behavior (COF). Since the increasing Cu content enhances intermetallic formation, superior wear resistance was observed in the samples containing a high amount of Cu sintered at higher temperatures up to 1.59 and 5.94 times. Optimum production parameters and chemical compositions were determined per the tests performed. [ABSTRACT FROM AUTHOR]

This work comments on a recent publication by Hajra et al. (Mater. Design 236 (2023) 112483), which claims to have presented compelling experimental and theoretical evidence in favour of the existence of an equilibrium C14-NbCr2 high-temperature Laves phase in the Cr-Nb system. In the present comment, evidence and conclusions reported in the paper of Hajra et al. are critically put into context of insight from previous works. From this it is concluded here, that the evidence in favour of an equilibrium C14-NbCr2 high-temperature Laves phase is, by far, not that compelling as claimed by Hajra et al.. Instead, the most direct evidence presented in the literature does not support the existence of an equilibrium C14-NbCr2 high-temperature Laves phase. Alternative interpretations of Hajra et al.’s evidence and conclusions are offered, and it is elaborated, which true gaps in knowledge exist concerning the Laves phases in the Cr-Nb system.

Transition metal-ruthenium alloys are promising candidates for ultra-high-temperature structural applications. However, the mechanical and electronic characteristics of these alloys are not well understood in the literature. This study uses first-principles density functional theory calculations to explore the structural, electronic, mechanical, and phonon properties of X3Ru (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) binary alloys in the tP16 crystallographic phase. We find that Mn3Ru, Sc3Ru, Ti3Ru, V3Ru, and Zn3Ru have negative heats of formation and hence are thermodynamically stable. Mechanical analysis (Cij) indicates that all tP16-X3Ru alloys are mechanically stable except, Fe3Ru and Cr3Ru. Moreover, these compounds exhibit ductility and possess high melting temperatures. Furthermore, phonon dispersion curves indicate that Cr3Ru, Co3Ru, Ni3Ru, and Cu3Ru are dynamically stable, while the electronic density of states reveals all the X3Ru alloys are metallic, with a significant overlap between the valence and conduction bands at the Fermi energy. These findings offer insights into the novel properties of the tP16 X3Ru intermetallic alloys for the exploration of high-temperature structural applications.

Developing efficient and anti‐corrosive oxygen reduction reaction (ORR) catalysts is of great importance for the applications of proton exchange membrane fuel cells (PEMFCs). Herein, we report a novel approach to prepare metal oxides supported intermetallic Pt alloy nanoparticles (NPs) via the reactive metal‐support interaction (RMSI) as ORR catalysts, using Ni‐doped cubic ZrO2 (Ni/ZrO2) supported L10−PtNi NPs as a proof of concept. Benefiting from the Ni migration during RMSI, the oxygen vacancy concentrations in the support are increased, leading to an electron enrichment of Pt. The optimal L10−PtNi−Ni/ZrO2−RMSI catalyst achieves remarkably low mass activity (MA) loss (17.8 %) after 400,000 accelerated durability test cycles in a half‐cell and exceptional PEMFC performance (MA=0.76 A mgPt−1 at 0.9 V, peak power density=1.52/0.92 W cm−2 in H2−O2/−air, and 18.4 % MA decay after 30,000 cycles), representing the best reported Pt‐based ORR catalysts without carbon supports. Density functional theory (DFT) calculations reveal that L10−PtNi−Ni/ZrO2−RMSI requires a lower energetic barrier for ORR than L10−PtNi−Ni/ZrO2 (direct loading), which is ascribed to a decreased Bader charge transfer between Pt and *OH, and the improved stability of L10−PtNi−Ni/ZrO2−RMSI compared to L10−PtNi−C can be contributed to the increased adhesion energy and Ni vacancy formation energy within the PtNi alloy. [ABSTRACT FROM AUTHOR]

Phases and equilibria involved in the isothermal section at 500 °C of the ternary Al-Fe-Pr system have been here investigated in the whole composition range by means of X-ray diffraction, optical and scanning electron microscopy, and electron probe microanalysis. Phase equilibria are characterised by the formation of two binary solid solutions, Pr2(FexAl1−x)17 with 0.34 ≤ x ≤ 1.00 (hR57–Th2Zn17) and Pr(FexAl1−x)2 with 0 ≤ x ≤ 0.20 (cF24–Cu2Mg), and four ternary compounds, τ1-PrFe2Al10 (oS52-YbFe2Al10), τ2-PrFe2Al8 (oP44-CeFe2Al8), τ3-Pr(FexAl1−x)12 with 0.28 ≤ x ≤ 0.44 (tI26-ThMn12) and τ4-Pr6(FexAl1−x)14 with 0.63 ≤ x ≤ 0.81 (tI80-La6Co11Ga3), which have been confirmed. The solid solubility ranges of the binary and ternary compounds have been considered and trends of their lattice parameters studied. The complete isothermal section has been obtained and the general features of the section are discussed and compared with those of other ternary systems of light R (La, Ce, Pr, Nd, Sm) with Al and Fe. [ABSTRACT FROM AUTHOR]

Phase equilibria were investigated between 200 and 800 °C in the Cu-Zn binary system. Wavelength dispersive spectroscopy (WDS) was performed to determine the equilibrium compositions, and differential scanning calorimetry (DSC) was performed to investigate the solidus and liquidus temperatures and the invariant reaction temperatures of the Zn-rich portion. The β/(α + β) boundary in the Cu-rich portion extended toward the Cu-rich side as the temperature decreased below the A2–B2 order–disorder transformation temperature, and the phase boundaries of the γ, δ and ε phases shifted toward the Cu-rich side. The liquidus temperatures of the ε + liquid were higher than those of the previous report. From the experimental results, the phase diagram of the Cu-Zn binary system was determined in the whole composition range. [ABSTRACT FROM AUTHOR]

The crystal structures of the U3Si2-related intermetallic compounds RE2Pd2Cd (RE = Nd, Sm, Gd, Dy) and RE2Ga2Mg (RE = Tb, Er, Tm, Lu) were studied from single crystal X-ray diffraction data at T = 90 K in order to understand the slightly enhanced U33 displacements of the 2a positions in their room temperature structures. The compounds Sm2Pd2Cd, Gd2Pd2Cd and Dy2Pd2Cd show a decrease of the ratio of U33 to U11 for the cadmium atoms, leading to a more isotropic behavior at low temperature, keeping the P4/mbm space group symmetry. Nd2Pd2Cd shows a translationengleiche symmetry reduction to space group P4bm along with a weak puckering effect with shorter (342.7 pm) and longer (345.7 pm) Cd–Nd distances within the Cd@Nd8 square prisms. This new, non-centrosymmetric superstructure variant was also observed for the magnesium compounds Tb2Ga2.069Mg0.931, Er2Ga2.104Mg0.896, Tm2Ga2.097Mg0.903 and Lu2Ga2.173Mg0.827, which show small degrees of Mg/Ga mixing. [ABSTRACT FROM AUTHOR]

Using first‐principle calculations, we investigate the rare‐earth intermetallic compound LaX3 (X = Sb and Sn) as a cathode material for rechargeable lithium‐ion batteries (LIBs). The calculations have been performed to look into the stability of the structure and the electronic properties of host LaX3 as well as its lithiated phases, LixLa1−xX3 (0 < x ≤ 1). In this study, we have observed a structural phase transformation of these intermetallic compounds from a cubic to a tetragonal structure upon lithiation to host structure. The ground state energy is calculated using the WIEN2k package to determine the structure stability and volume change due to lithium addition, which is further used to calculate the formation energy, open circuit voltage (OCV), and lithium‐ion storage capacity. The equilibrium structural parameters for all the phases are determined by achieving a total energy convergence of 10−4 Ry. The estimated band structure along high‐symmetry lines in the first Brillouin zone and the total as well as partial density of states demonstrate unequivocally that the addition of lithium does not change the metallic nature of these electrode materials. We have also calculated the theoretical lithium‐ion storage capacity and OCV for all the compounds. Despite a higher value for OCV larger than 5 V, many of the investigated materials could not be found suitable from a synthesis point of view due to positive formation energies. The formation energy calculation shows that LaSb3, with a 50% concentration of Li, is the most stable compound out of those investigated here. The calculated OCV for Li0.5La0.5Sb3 is 4.27 V. This is substantially higher than the value obtained up to this point for LIBs, which ranges from 3.20 to 3.65 V/cell. These improved results related to the most stable alloy (Li0.5La0.5Sb3) investigated in this work indicate that it is necessary to check the experimental feasibility of its synthesis and actual device performance. [ABSTRACT FROM AUTHOR]

Transition metal-ruthenium alloys are promising candidates for ultra-high-temperature structural applications. However, the mechanical and electronic characteristics of these alloys are not well understood in the literature. This study uses first-principles density functional theory calculations to explore the structural, electronic, mechanical, and phonon properties of X3Ru (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) binary alloys in the tP16 crystallographic phase. We find that Mn3Ru, Sc3Ru, Ti3Ru, V3Ru, and Zn3Ru have negative heats of formation and hence are thermodynamically stable. Mechanical analysis (Cij) indicates that all tP16-X3Ru alloys are mechanically stable except, Fe3Ru and Cr3Ru. Moreover, these compounds exhibit ductility and possess high melting temperatures. Furthermore, phonon dispersion curves indicate that Cr3Ru, Co3Ru, Ni3Ru, and Cu3Ru are dynamically stable, while the electronic density of states reveals all the X3Ru alloys are metallic, with a significant overlap between the valence and conduction bands at the Fermi energy. These findings offer insights into the novel properties of the tP16 X3Ru intermetallic alloys for the exploration of high-temperature structural applications. [ABSTRACT FROM AUTHOR]

The ternary germanide Mg5.57Ni16Ge7.43 (cubic, space group Fmm, cF116) belongs to the structural family based on the Th6Mn23‐type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three‐core‐shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a coordination number of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three‐core‐shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2. [ABSTRACT FROM AUTHOR]