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The stannide Li4Rh3Sn5 was synthesized by induction-melting of the elements in a sealed tantalum ampoule. The sample was characterized by powder X-ray diffraction and the Li4Rh3Sn5 structure was refined from single-crystal X-ray diffractometer data: new type, orthorhombic space group Pnnm, a = 813.27(11), b = 2,259.6(3), c = 449.94(6) pm, wR2 = 0.0486, 1577 F2 values and 64 variables. The rhodium and tin atoms form a rigid covalently bonded three-dimensional [Rh3Sn5] network with Rh–Sn distances ranging from 263 to 277 pm. Within this network, the tin atoms form two different substructures, i. e., angled Sn1–Sn4–Sn5 units and isolated Sn2 and Sn3 atoms. The lithium atoms fill cages within the [Rh3Sn5] network. They have coordination numbers 11, 12 and 13. Based on their different 7Li resonance shifts two groups of distinct local environments can be identified in an intensity ratio of 3:1, namely the 4g Wyckoff sites Li1, Li2, and Li5, and the 2c Wyckoff sites Li3 and Li4. The whole Li4Rh3Sn5 structure can be described by condensation of the Li1@LiRh4Sn6, Li2@Li2Rh4Sn6, Li3@Li2Rh4Sn6, and Li4@Li2Rh4Sn6 polyhedra, including the Li5 atoms which are within the Li1 coordination sphere. The 119Sn Mössbauer spectrum of Li4Rh3Sn5 shows a superposition of two sub-signals in a ratio of 60:40. The two sub-signals with similar isomer shift are discernable through their quadrupole splitting parameters: ∼1.93 mm s−1 for the tin atoms of the angled Sn3 unit, and ∼1.20 mm s−1 for the isolated tin atoms with a more symmetric electron density distribution. [ABSTRACT FROM AUTHOR]

SrPd2Sn2 was synthesized by a reaction of the elements in a sealed tantalum tube in an induction furnace followed by annealing in a muffle furnace to increase crystallinity. The polycrystalline sample was studied by powder X-ray diffraction: P4/nmm, a = 464.00(7), c = 1,058.4(4) pm and V = 0.2279 nm3. The CaBe2Ge2-type structure was refined from single-crystal X-ray diffractometer data: a = 464.09(4), c = 1,059.64(8) pm, wR = 0.0507, 307 F2 values and 17 variables. The single crystal shows small defects (95.9(5) %) on the Pd2 site and 73(5) % Sn2/27 % Pd3 mixing on one 2c site. The refined composition of the single crystal is SrPd2.23Sn1.73. The palladium and tin atoms form a three-dimensional, covalently bonded [Pd2.23Sn1.73] network with short Pd–Sn distances (263.3–271.4 pm). The two crystallographically independent palladium atoms in the network have tetrahedral and square pyramidal tin coordination, respectively. Within the [Pd2.23Sn1.73] network the strontium atoms fill larger cavities. The strontium atoms are coordinated by nine palladium and nine tin atoms. [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 M2Al16Pt9 series with M = Ca, La–Nd and Sm–Gd was synthesized from the elements in analogy to the literature known compounds Ce2Al16Pt9 and Sr2Al16Pt9. All compounds crystallize in the orthorhombic crystal system with space group Immm and have been characterized by powder X-ray diffraction. For La2Al16Pt9 and Eu2Al16Pt9 also single-crystal investigations have been conducted. In all cases, Al3Pt2 as well as the members of the REAl5Pt3 series (YNi5Si3 type, space group Pnma) have been observed as side phases. Annealing led in all cases to an increase of the side phases, suggesting that the title compounds decompose peritectically. In the crystal structures, polyanionic [Al16Pt9]δ– networks can be found with large fourfold capped hexagonal prismatic cavities (M@Al6Pt6Al4), which host the respective M atoms. As seen from the unit cell volumes, the La–Nd, Sm and Gd compounds exhibit a formally trivalent oxidation state while the Ca and Eu atoms in Ca2Al16Pt9 and Eu2Al16Pt9 are divalent. [ABSTRACT FROM AUTHOR]

Bimetal components play a vital role in fulfilling diverse material requirements of lightweight structures, heat transfer, and functionally graded applications. In bimetallic castings, the presence of microgap defects significantly affects the bond strength between dissimilar materials. The dissimilar joining of Al-SS304, achieving a high-quality bond, relies on several factors, such as pouring temperature of molten aluminum, preheating temperature of SS insert, thickness of SS inserts, and the choice of interlayer coating materials. In the present work, the Zn, Cu, and Sn interlayers were used to produce Al-SS304 bimetallic castings since they showed good bond between aluminum and stainless steel. In addition to that, a machine learning algorithm was employed to predict the microgap at the interface between aluminum and stainless steel. Both destructive and nondestructive testing techniques were utilized to predict the microgap defects formed at the interface. Response surface methodology was employed to systematically perform the experiments, and a dataset for a machine learning algorithm was formed using the results from liquid penetrant testing. The results from this prediction model were compared with those obtained from the destructive shear punch test results. Notably, the samples without defects displayed a maximum load exceeding 26 kN, whereas the samples with microgap defects exhibited a maximum load below 26 kN. A confusion matrix was used to validate the machine learning classification model. [ABSTRACT FROM AUTHOR]

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]

Despite many years of research and continuous improvements in scientific equipment, some of the thermodynamic properties of binary systems are still unknown, or are only theoretically predicted or calculated. This situation often arises from the difficulties in preparing alloys for experimental measurements. The alloys from the Mg-Pd system, especially for the Pd-rich side, are difficult to produce, and the availability of thermodynamic data is very limited. Therefore, this paper presents calorimetric studies on the standard enthalpy of formation of alloys from the Mg-Pd system, which were prepared using mechanical alloying. Three alloys (S1, S2, and S3) were synthesized, homogenized, and subjected to X-ray diffraction (XRD) analysis to investigate their phase composition. The XRD studies showed that the alloys designated as S1 and S2 were the intermetallic phases Mg6Pd and Mg0.9Pd1.1, and the S3 sample was a mixture of MgPd and MgPd3 intermetallic phases. Their heat effects, measured by drop calorimetry, were used to calculate the values of the standard enthalpies of formation of the prepared phases. The values obtained were as follows: −27.5 ± 1.1 kJ/mol at. for the Mg6Pd intermetallic phase, −72.7 ± 1.0 kJ/mol at. for the Mg0.9Pd1.1 intermetallic phase, and −46.8 ± 1.5 kJ/mol at. for the alloy which was a mixture of MgPd and MgPd3. These data were compared with values from the existing literature on the enthalpy of formation of alloys, as well as with data calculated using Miedema's model. [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]

Shape memory alloys based on the Ni–Ti system derive their versatile properties from the non-stoichiometric intermetallic compound NiTi. The transformation temperature associated with its shape memory effect is dependent on composition, which can be controlled by minor additions of a third element like iron. This work considers the formation of various intermetallic compounds and the evolution of phases during the sintering of ternary Ni–Ti–Fe powder compacts. Elemental powder mixtures of nickel, titanium and iron were prepared by adding 0–20 at.% Fe to equiatomic Ni–Ti. The powders were compacted into discs and sintered by heating to 1200 °C in a differential scanning calorimeter. In separate experiments, heating was interrupted to identify the phases present in the partially sintered samples at various temperatures. The microstructures of the sintered samples were characterized using scanning electron microscopy. The distribution of nickel, titanium and iron in the samples was studied with EDS mapping and the phases present were identified using XRD. In the equiatomic Ni–Ti powder compact, NiTi2, NiTi and Ni3Ti were formed in the solid state (< 942 °C) through diffusion. At 942 °C a strong reaction between the remaining titanium and NiTi2 takes place, leading to the formation of a liquid. At 1120 °C, NiTi and Ni3Ti combine to form a liquid. These reactions are affected by the addition of iron to the powder mixture. The results show that at 20 at.% iron in the ternary compact, the first reaction occurred at 999 °C, instead of 942 °C for the binary composition and iron did not form any compound with nickel or titanium. Instead, the iron could replace nickel in NiTi2 and in NiTi, forming (Fe, Ni)Ti2 and (Fe,Ni)Ti. This leads to more Ni3Ti formation and explains why the reaction at 1120 °C is more prominent at high iron contents. A linear dependence on the iron content in the sample was also observed for the onset temperatures for two split exothermic peaks in the DSC curves. The results also suggest that the temperatures associated with the β-Ti + (Fe, Ni)Ti2 → L and (Fe, Ni)Ti2 → (Fe,Ni)Ti + L reactions depend on the ratio of iron to nickel in (Fe, Ni)Ti2. [ABSTRACT FROM AUTHOR]

The joining of Ti-5Al-2.5Sn to AA2219 dissimilar alloys was studied through vacuum diffusion bonding (VDB). Samples were bonded at various temperatures under 15 MPa pressure for 45 minutes. The mechanical properties of the bonded lap joints were evaluated with shear and Vickers micro hardness tests, while scanning electron microscopy (SEM) was utilized to examine their microstructure. Energy-dispersive spectroscopy (EDS) and microstructural analysis revealed that the interfacial oxide layer diminished as the bonding temperature increased. The X-ray diffraction (XRD) analysis showed that TiAl3was the only intermetallic compound formed at the interface. Results indicated that as bonding temperature increased, the interface micro hardness first increased and then decreased at higher temperatures. Furthermore, the shear strength of the bonded joint improved with rising temperature from 525 °C to 540 °C but decreased at 555 °C because of the development of a thick intermetallic layer. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) was first used to deposit products made of SHS-produced intermetallic alloy Ti20Al3Si9 powder on the Ti substrate. It was shown that formed Ti20Al3Si9 alloy/Ti substrate composites have a strong bond. The influence of SLM parameters for processing SHS-produced powder on microstructure and phase composition of clad samples was studies. [ABSTRACT FROM AUTHOR]

In this paper, the results of a study of the structure and phase composition of the hot-dip aluminizing coatings formed on the commercially pure titanium surface in AW-6063 aluminum alloy melt after heat treatment at 700 and 850 °C are presented. It is shown that as a result of aluminizing on the titanium surface, a homogeneous coating 30–40 µm thick without defects is formed. The hot-dip aluminizing coating consists of aluminum and the intermetallic compound TiAl3, located at the boundary with the substrate. Heat treatment results in the formation of a heterogeneous coating structure: its outer layer has a frame-type structure consisting of TiAl3 particles surrounded by an Al2O3 + TiO2 grid, and the inner continuous layer adjacent to the titanium consists of TiAl2, TiAl, and Ti3Al intermetallic layers. Increasing in the heat treatment temperature and/or holding time results in an increase in the thickness of both the outer and boundary layers of the coating. A mechanism for the formation of the coating structure via heat treatment is proposed. The scratch test method was used to evaluate the cohesive and adhesive strength of the coatings, and their scratch hardness was determined, which averaged 200 MPa. It was shown that the coating structure formed during heat treatment at 850 °C ensures higher resistance to cohesive failure. [ABSTRACT FROM AUTHOR]

As advances are being made regarding the performance of nuclear fuels, uranium carbides, and composites, such as (U,Zr)C and UO 2 + UC x , have recently gained significant interest for deployment in nuclear space propulsion and high temperature gas-cooled reactors, respectively. However, the phase equilibria of several fission products in carbide systems remain unknown and may impact the overall fuel performance, specifically for particle nuclear fuels that are designed for commercial nuclear energy. Furthermore, comprehensive thermodynamic data on Rare Earth (RE) carbides, such as the Nd-C and Ce-C binary systems, remain limited. Presented in this study are the synthesis methods and characterizations of several Nd-C and Ce-C compositions. The findings from this research provide insights on the stability of RE-C binaries that form in irradiated nuclear fuels and address a critical knowledge gap in the current state of thermodynamics for two key RE-C systems. [ABSTRACT FROM AUTHOR]

In this study, the effects of sintering temperatures and pressures on densification, crystalline phases, microstructural characterization and mechanical properties of mechanical alloyed equimolar CoCrFeNiMo HEA were investigated. The alloy was composed of major BCC and minor FCC solid solutions coexisting after 40 h of milling. Increasing milling time caused to increase in lattice strain and a decrease in crystallite size. Furthermore, sintering temperature and pressure resulted in the decomposition of the BCC metastable phase and the formation of intermetallic phases and the FCC phase. Herein, increasing sintering temperature and pressure led to decrease lattice strain and increase crystallite size. Moreover, sintering temperature and pressure caused to formation of new intermetallic phases in HEA2 and HEA3. Results revealed that increasing sintering temperatures and pressures of equimolar CoCrFeNiMo end up with a reduction of large pore, enhancement of density value from 7.53 ± 0.02 to 8.78 ± 0.005 g/cm3, hardness from 3.915 to 8.316 GPa, and increment of wear rate from 21.8 × 10−7 to 57.6 × 10−7 mm3/Nm. [ABSTRACT FROM AUTHOR]

The CeCr2Al20-type aluminides RETi2Al20 (RE = Eu, Gd, Tb, Dy and Yb), space group F d 3 ‾ m , show the formation of solid solutions RETi2Al20−xGax 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−xGax 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−xGax 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–xCaxPdMg. Further phase analytical studies showed that Eu4PdMg does not allow substitution with strontium. The polycrystalline Eu4–xCaxPdMg 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]

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]

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]

A novel systematic study of interdiffusion-driven phase growth in complex concentrated alloys (CCAs) is presented w.r.t increasing configurational entropy. Diffusion couples of M/Sn (M: Ni, CoNi, CoCrNi, CoFeNi, CoCrFeNi and CoCrFeMnNi) are annealed at 225 °C for 48 h to comprehensively explore diffusion behaviour in CCAs. Except Ni/Sn, all the systems exhibited two-phase layers, one of which is (CoNi)Sn3. Cr, Fe and Mn exhibited limited solubility in (CoNi)Sn3 and formed a separate intermetallic phase in the interdiffusion zone (IDZ). Contrary to the notion of sluggish diffusion, the overall thickness of the IDZ did not follow a monotonic decrease with increasing number of elements. The integrated diffusivities D int ∨ for (CoNi)Sn3 phase decelerated as the solutes (Cr, Fe and Mn) occupied 3d transition element sublattice. Our results demonstrate non-sluggish diffusion-controlled phenomenon (phase growth) in CCAs and substantiate the interplay of thermodynamic and kinetic factors in evolution of multicomponent intermetallics. [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.

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 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]

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]