Crystal Structure Of Intermetallic Compounds Research Articles

Stability of intermetallic compounds: Geometrical and topological aspects

We have applied a universal geometrical-topological approach to analyze 23507 robust crystal structures of intermetallic compounds, which are deposited in the Inorganic Crystal Structure Database. All the structures were represented as three-periodic nets and arranged into 2551 topological types each of which possesses a unique system of interatomic bonds. For all 104309 topologically different atoms in these structures their environments (local atomic configurations, LACs) were explored within the first and second coordination shells. In total, 5251 topologically distinct types of coordination polyhedra and 21450 types of two-shell LACs were distinguished and deposited into our interactive database system TopCryst. We have found that the local density of the nearest environment of an atom naturally depends on its coordination number (CN) with a maximum at CN = 9. It was shown that LACs at CN ≥ 9 follow the close packing model of hard balls with Slater's atomic radii. At lower CNs, covalent interactions make a significant contribution that results in a decrease of the local density. Resting upon the dependence between the local density and CN we have proposed criteria for the estimation of the geometric instability (disbalance) of both a separate LAC and the whole intermetallic structure. We have revealed that strong geometric disbalance can be caused by errors in the structural data, incorrect description of the crystal structure, non-metallic nature of the chemical bonding or metastability of the crystalline phase. Thus the instability criteria can serve as important indicators of the structure inconsistency that is especially useful for checking crystallographic information on intermetallics or validating the structural models predicted by theoretical methods.

Metallurgical and Mechanical Characteristics of an AA5183 Alloy Plate Performed by a Cold Metal Low-Power Additive Manufacturing Technology

In this work, an AA5183 alloy plate was successfully deposited by low-power cold metal transfer technology. The forming defects, microstructural characteristics, and mechanical properties were investigated. The results show that the number of defects increases gradually along the building direction of the deposited plate. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, electron backscatter diffraction, and transmission electron microscopy were employed to study the distribution of alloying elements, deposited microstructural characteristics, and the crystal structure of intermetallic compounds in the Al alloy plate. The tensile samples perpendicular to the building direction presented greater tensile strength and superior plasticity compared to those parallel to the deposition direction. The average UTS was 327 ± 0.65 MPa and the average EL was 30.6 ± 2.0%. The UTS of conventionally forged 5083-H32 (Al-Mg4.5) alloy is 324 MPa; the UTS of extruded 5083-H116 (Al-Mg4.5) alloy is 305 MPa. Further, the strength of our prepared plate reaches the value needed for industrial applications of the 5083 Al alloy. The differences in the strength and plasticity of the samples assessed under multiple sampling methods were analyzed based on a synergistic strength–ductility mechanism.

A Critical Review on the Properties of Intermetallic Compounds and Their Application in the Modern Manufacturing

AbstractAdvancement in modern manufacturing processes is allowing researchers to develop new alloy configurations for different applications to reduce weight and increase efficiency. Many alloy combinations are produced that randomly generate different phases of intermetallic compounds (IMCs) in the structure during manufacturing which show unique mechanical and chemical properties. But, the fundamental knowledge of different IMCs is scattered across the material research domain. Thus, in this review, the crystal structures of IMCs are thoroughly discussed which are having structural and functional applications. Furthermore, the issues associated with the dissimilar Fe‐Al, Fe‐Ni, and Ni‐Al systems via modern manufacturing processes such as arc additive manufacturing have been discussed. Moreover, detailed knowledge of ferro‐nickel, nickel‐aluminides, and ferro‐aluminides formed at the interface during the dissimilar deposition in modern manufacturing is provided. Currently, a few transition metal IMCs and some Heusler alloys, are the most promising and are used in applications. The addition of a third alloying element provides the broadening effect on the phase domain of a specific IMC. Furthermore, it has been observed that modern manufacturing processes such as additive manufacturing and others are new and advanced manufacturing technologies used for dissimilar metal deposition, which can control the IMCs in a more favorable direction.

Phase transformations of the nanostructured iron-platinum system upon heating

Joint reduction with hydrazine from aqueous solutions of precursors produced nanostructured powders of the Fe – Pt system in three characteristic phase regions. The samples were subjected to heat treatment in the range up to 800 ° C and characterized at all stages by X-ray diffraction and high-resolution electron microscopy; the elemental composition of the samples was refined by the method of optical emission spectroscopy with inductively coupled plasma. In the initially obtained samples, only a part of the substance is detected by diffraction-the largest, platinum-rich crystals with dimensions of about 10 nm (established from TEM images and broadening of diffraction lines). The fcc-type cubic lattice parameters and the composition of the observed crystals were estimated from the distances between the regular bands in TEM images, identified with atomic rows, based on the composition dependence of the bulk characteristics of mixed iron-platinum phases (according to ICDD databases). In the course of heating, the processes of phase transformation are traced in detail, the parameters of the resulting crystal structures of intermetallic compounds are fixed, and the mechanisms of these transformations are discussed. Based on the measured lattice parameters, the thermal expansion coefficients of some mixed phases are calculated and the phase compositions are estimated at different stages of heat treatment.

Intermetallic Compounds KnMm (М = Ag, Au, As, Sb, Bi, Ge, Sn, Pb): Geometrical and Topological Analysis, Cluster Precursors, and Self-Assembly of Crystal Structures

A geometrical and topological analysis and simulation of the self-assembly of the crystal structures of intermetallic compounds formed in the K–M (M = Ag, Au, As, Sb, Bi, Ge, Sn, Pb) systems have been performed using computation methods (the ToposPro software). The precursor metal clusters of KnMm crystal structures are determined based on the algorithms of structure-graph decomposition in cluster structures and construction of the basic net of structure in the form of a graph with nodes corresponding to cluster centers. Tetrahedral metal clusters, forming packings in the K3Bi-cF16, K3Bi-hP8, K2As2-oP16, K2Sb2-mP16, and K2Sb2-mP32 crystal structures; tetrahedral metal clusters and spacers for the K(K2As2)2-mC18, K4(Pb4)-tI64, and K2(Au4)-hP12 structures; polyhedral metal clusters KK4Pb12 and spacers for the Pb12K(K4Pb12)-cI58 structure; and dodecahedral metal clusters KGe20 and spacers for the K3Ge3(KGe20)-cP54 structure have been found. The symmetry and topology code of the self-assembly of crystal structures of intermetallic compounds KnMm has been reconstructed from precursors $$S_{3}^{0}$$ in the following form: primary chain $$S_{3}^{1}$$ → microlayer $$S_{3}^{2}$$ → microframework $$S_{3}^{3}$$ .

Intermetallic Compounds NakMn (М = K, Cs, Ba, Ag, Pt, Au, Zn, Bi, Sb): Geometrical and Topological Analysis, Cluster Precursors, and Self-Assembly of Crystal Structures

A geometrical and topological analysis has been performed, and self-assembly of the crystal structures of intermetallic compounds formed in the Na–M (M = K, Cs, Ba, Ag, Pt, Au, Zn, Bi, Sb) systems has been simulated using computer methods (the ToposPro software). The NakMn precursor metal clusters of the crystal structures are determined based on the algorithms of structural-graph decomposition in cluster structures and construction of the basic net of the structure in the form of a graph whose nodes correspond to the cluster centers. The tetrahedral metal clusters M4, forming packets in the Na3Bi-hP8, Na2Bi2-tP4, and Na2Sb2-mP16 crystal structures; tetrahedral metal clusters M4 and spacers for the Na2(Au4)-cF24 and Ba2(Na4)-hP12 framework structures; octahedral clusters M6 for the Na4Au2-tI12 structure; octahedral M6 and tetrahedral M4 metal clusters for the Na2(Na4)(Ba6)-cF96 and Au2(In4)(Na6)-cF96 structures; and icosahedral metal clusters M13 for the Na(Zn13)-cF116 structure are found. The symmetry and topology code of the self-assembly of crystal structures of NakMn intermetallic compounds has been reconstructed from precursor metal clusters $$S_{3}^{0}$$ in the following form: primary chain $$S_{3}^{1}$$ → microlayer $$S_{3}^{2}$$ → microframework $$S_{3}^{3}$$ .

Intermetallic Compounds LikMn (M = Ag, Au, Pt, Pd, Ir, Rh): Geometrical and Topological Analysis, Tetrahedral Cluster Precursors, and Self-Assembly of Crystal Structures

A combinatorial and topological analysis has been performed and self-assembly of the crystal structures of intermetallic compounds formed in the Li–M (M = Ag, Au, Pt, Pd, Ir, Rh) systems has been simulated using computer methods (the TOPOS program package). The LikMn precursor metal clusters are determined based on the algorithms of graph expansion in cluster structures and construction of basic 2D and 3D nets in the form of graphs, the nodes of which correspond to the cluster centers. The tetrahedral metal clusters M4, forming packets in the (LiPd3)(Pd4)-cF32, (Li2Rh2)(Rh4)-oI8, (Li2Pd2)(Pd4)-mP4, LiAu3-cP4, Li1.84Ag2.16-cF4, Li2Ag2-tI8, Li2Pd2-cP2, Li2Rh2-hP2, and Li3Pd-cF16 crystal structures; tetrahedral metal clusters M4 and spacer atoms for the Li2(Pt4)-сF24 framework structure; and two-layer clusters 0@М4@M22 for the (Li4)(Li12Ag10)-cI52 structure are found. The symmetry and topology code of self-assembly of the crystal structures of LikMn intermetallic compounds has been completely reconstructed from precursor metal clusters $$S_{3}^{0}$$ in the following form: primary chain $$S_{3}^{1}$$ → microlayer $$S_{3}^{2}$$ → microframework $$S_{3}^{3}$$.

Crystal Chemistry of Lithium Intermetallic Compounds: A Survey

The structural chemistry of lithium intermetallic compounds that are formed in Li–М binary systems where М = Ca, Sr, Ba, Mg, Zn, Cd, and Hg is surveyed. It is for the first time that the crystal structures of intermetallic compounds are classified in terms of polyhedral precursor metal clusters (in the program package ToposPro). The precursor metal clusters of crystal structures are identified using the algorithms of partitioning structural graphs into cluster structures and via the design of the basal 3D network of the structure in the form of a graph whose nodes correspond to the positions of the centers of precursor clusters. Tetrahedral precursor metal clusters M4 are identified for the crystal structures LiZn3-oC4, LiMg3-hP2, LiCd3-hP2, LiHg3-hP8, (LiMg3)(Li2Mg2)-tI16, Li2Zn2-cF16, Li2Cd2-cF16, Li2Hg2-cP2, Li3Cd-cF4, and Li3Hg-cF16; tetrahedral metal clusters M4 are found for the framework structures with spacer atoms Sr(Li2Sr2)-tP20, Ca2(Li4)-cF24, and Ca2(Li4)-cP12; tetrahedral metal clusters M4 and rings M6, for framework structures Ba3Li2(Li10)-hP30 and Ba3Li2(Li4In6)-hP30; icosahedral metal clusters M13 for the framework structure Li(Zn13)-cF112; bilayer tetrahedral metal clusters 0@М4@M22 for the framework structure Li23Sr6-cF116; and deltahedra М17 and deltahedra М30, for framework structures Sr4Li14 [Sr(Sr4Li12)] [(Sr2 (Sr8Li18)]-tI252 and Ba4Li14 [Ba(Ba4Li12)][(Ba2 (Ba8Li18)]-tI252. The scenario of crystal structure self-assembly from precursor metal clusters S30 in intermetallic compounds is reconstituted as: primary chain S31→ microlayer S32→ microframework S33.

Modeling of self-organization processes in crystal-forming systems: Symmetry and topology code for the cluster self-assembly of crystal structures of intermetallic compounds

We performed the combinatorial and topological modeling of 1D, 2D, and 3D packs of symmetrically connected metal clusters in the form of tetrahedra А4. Three types of 1D chains with tetrahedral connectivity of 4, 6, and 8 were used to model 2D layers L-1, L-2, and L-3 and 3D frameworks FR-1, FR-2, FR-3, and FR-4. The model structures of the identified suprapolyhedral precursor clusters were used in topological analysis of crystal structures of intermetallic compounds (program package TOPOS and data bases ICSD and CRYSTMET). A match was found between the topological models of tetrahedral 3D frameworks and all types of crystal structures formed in binary systems; in Au–Cu: FR-1 for Cu3Au-cP4 (Auricupride), Cu2Au2-tP2 (Tetraauricupride), CuAu3-cP4 (Bogdanovite), and Cu2–x Au2 + x -cF4; in Mg–Cd: FR-3 for Mg3Cd-hP8, Mg2Cd2-oP4, MgCd3-hP8, and Mg2–x Cd2 + x -hP2; in Li–Hg: FR-2 for Li3Hg-cF16 and Li2Hg2-cP2 and FR-3 for LiHg3-hP8; in ternary system Li–Ag–Al: FR-2 for LiAg2Al-cF16 and Li2AgAl-cF16; and in quaternary system: framework FR-2 for LiMgPdSn-cF16. Framework FR-4 was identified in ternary intermetallic compounds A(Li2Sn2)-tI20, where A = Cu, Ag, Au. The structures of precursor nanoclusters were identified for other most abundant types of crystal structures of intermetallic compounds. For this purpose, we used the algorithms for partitioning the structural graph into nonintersecting cluster substructures and constructed the basal 3D network of the crystal structure in the form of a graph whose nodes correspond to the positions of the centers of precursor clusters. The cluster self-assembly was modeled for the following intermetallic compounds: Mg2Cu4-cF24, MgSnCu4-cF24, (ZrCu)Cu4-cF24,Mg2Zn4-hP12, (CaCu)Cu4-hP6, Cr3Si-cP8, Lu3Co(Fe3C)-cP16, Ca2Ge2(Cr2B2)-oC8, Y2Ni2(Fe2B2)-oP8, AlB2-hP3, Ca2Ge-oP12, CaHg2-hP3, Co2Ge(Ni2In)-hP6, Cs2Hg4-oI12, Ba4Po4-cF8, Mn5Ge3-hP16, and NaZn13-cF112. The symmetry and topological code of self-assembly from precursor nanoclusters was reconstituted for all crystal structure types of intermetallic compounds as: primary chain → microlayer → microframework. An abundance frequency analysis of topological and symmetry routes for the generation and evolution of precursor clusters enabled us to elucidate the crystal-formation laws in intermetallic systems on the microscopic level.

Modeling of the self-organization processes in crystal-forming systems. Tetrahedral metal clusters and the self-assembly of crystal structures of intermetallic compounds

A combinatorial and topological modeling of 1D, 2D, and 3D packings of symmetrically linked A4 tetrahedra has been performed. Three types of 1D chains with tetrahedra connectivities of 4, 6, and 8 were used to model 2D layers L-1, L-2, and L-3 and 3D frameworks FR-1, FR-2, FR-3, and FR-4. A family of tetrahedral structures with FR-1, FR-2, and FR-3 frameworks has been selected among the intermetallic compounds with chemical compositions of A 3 B, A 2 B 2, AB 3, A 2 BC, AB 2 C, and ABCD; this family includes more than 1900 compounds (TOPOS program package). It is found that the topological models of tetrahedral 3D frameworks are in correspondence with all types of the crystal structures formed in Au–Cu binary systems (FR-1 for Cu3Au (auricupride), Cu2Au2 (tetraauricupride), and CuAu3 (bogdanovite)), in the Mg–Cd system (FR-3 for Mg3Cd, Mg2Cd2, and MgCd3), in the Li–Hg system (FR-2 for Li3Hg and Li2Hg2 and FR-3 for LiHg3), in the Li–Ag–Al ternary system (FR-2 for LiAg2Al and Li2AgAl), and in the Li–Mg–Pd–Sn quaternary system (FR-2 for LiMgPdSn). Framework FR-4 has been established in ternary intermetallic compounds A(Li2Sn2); A = Cu, Ag, Au.

New icosahedral nanoclusters in crystal structures of intermetallic compounds: Topological types of 50-atom deltahedra D50 in samson phases β-Mg2Al3 and ɛ-Mg23Al30

A database of intermetallic compounds has been compiled using the TOPOS program package. This database includes 514 topological types, containing 12- and 13-atom icosahedral i clusters. An isolated group of 1649 i clusters is described by 14 point groups and their maximum symmetry D3d (\(\bar 3\)m) and Th(m\(\bar 3\)) is established, respectively, in 47 and 25 types of crystal structures. A structural analysis of the outer quasispherical shells showed that local 63-atom i configurations 1@12@50, which contain 50 atoms in the second layer, are implemented in 8 out of 19 cases. Examples of new topologically different types of 50-atom D50 deltahedra in the Samson phases ɛ-Mg23Al30 and β-Mg2Al3 are presented. Four topologically different sites with coordination numbers of 5, 6, 6, or 7 are established in the ɛ shell and seven sites with coordination numbers of 5, 5, 6, 6, 6, 6, or 7 are found in the β shell. The inner i clusters for the β-Mg2Al3 structure (with the symmetry \(\bar 3\)m) and the ɛ-Mg23Al30 structure (with the symmetry \(\bar 3\)) have a similar chemical composition, i.e., Mg7Al6 and Mg6Al7, and their 50-atom shells are chemically identical to 18Mg + 32Al. The configurations found supplement the series of known two-layer icosahedral Bergman and Mackay clusters in the form of deltahedra with 32- and 42-atom shells.

Nanoclusters based on pentagondodecahedra with shells in the form of D32, D42, and D50 deltahedra in crystal structures of intermetallic compounds

The TOPOS software package has been used to form a database of intermetallic compounds containing pentagondodecahedral d clusters (528 crystal structures of intermetallic compounds, 111 topological types, and 47 space symmetry groups). On the whole, 606 atomic d configurations have been selected which are described by 14 point symmetry groups. Examples of nanoclusters are presented which are precursors of the crystal structures of intermetallic compounds with the outer shell in the form of deltahedra D, which are formed above dodecahedra. These nanoclusters are identified in the automatic mode of structural data processing: D32 (K8In6Ge40, Cs30Na3Sn162), D 42 (Ru3Be17, Y3Cd18, Ca3(Cd17Al)), and D 50 (Yb3Zn18, Ce3(Au14Sn3), Pr3Cd18, Eu4Cd25), where 32, 42, and 50 are the numbers of atoms in the shell. Similar deltahedra were found previously in icosahedral nanoclusters (precursors of intermetallic compounds). Structures with the dodecahedral nanocluster precursors containing D42 and D50 deltahedra are approximants of MCd5.7 (M = Yb or Ca) quasicrystals and belong to the family of MCd6 (M = Ce, Pr, Nd, Sm, Eu, Gd, Dy, Yb, Y, or Ca).

Formation of the crystal structure of intermetallic compounds in mechanically activated Ni-Al and Ti-Al systems during self-propagating high-temperature synthesis

The dynamics of structural and phase transitions during heterogeneous reaction in mechanically activated mixtures has been investigated by X-ray diffraction, scanning electron microscopy, and dynamic synchrotron radiation diffraction. It is shown that the mechanisms of formation of the structure of reaction products are significantly different, depending on the temperature mode of the synthesis. Upon slow heating, the process is multistage and includes several intermediate crystalline phases. Upon fast heating, the transformation in the combustion wave occurs much faster, with only one intermediate phase observed.

Golden Section in the Structure of Metals

Main aspects of a new division of crystallography based on the concept of polytopes (four-dimensional polyhedrons) are considered. The possibilities of this concept for describing composite crystal structures of intermetallic compounds and the atomic mechanism of polymorphic transformations are discussed. In all the cases studied icosahedral polyhedrons containing fifth-order symmetry axes play a special role. In its turn, this is a manifestation of the role of golden section in the structure of condensed phases.

Crystal Structure of a Novel Cerium Indide Ce6Pt11In14.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Crystal structure of a novel cerium indide Ce6Pt11In14

The crystal structure of a new intermetallic compound Ce6Pt11In14 has been determined from single crystal X-ray data and was refined by a full-matrix least-squares method down to R1=0.0497 for 1215 structure factors and 96 parameters. The unit cell is monoclinic, space group C2/m, Z=2 with the lattice parameters: a=22.729(5)Å, b=4.3960(10)Å, c=14.780(3)Å and β=118.35(3)°. It represents a new type of crystal structure of intermetallic compounds.

Phase Stability of Intermetallic Compounds

New crystal structure maps have recently been constructed for predicting crystal structures of intermetallic compounds. The phase stability of metal hydrides formed in hydrogen-storage compounds has been elucidated from the nature of the chemical bonds between atoms.

Real disordered crystal structure and Curie temperature of intermetallic compounds Y 2Fe 17− xM x (M=Si or Al)

The crystal structure of intermetallic compounds Y 2Fe 17, Y 2Fe 15.3Al 1.7 and Y 2Fe 15.3Si 1.7 was studied by powder X-ray and neutron diffraction. The real disordered structure of the compounds was found to be a disordered variant of the Th 2Ni 17-type structure, in which the Y atoms from the 2b sites substitute in part the Fe “dumbbells” on 4f sites and the Fe atoms occupy part of vacant 4e sites. Besides, the Y atoms implant in 2c sites in the iron plane of the compounds, which causes plane distortions and splitting of the 12j Fe sites into two subsites. The substitution of Fe by Si or Al was found to have a preferential character for sites in the order: 12k, 4f, 4e, 6g and 12j. Partial substitution of Al or Si for Fe is established as resulting in an increase in the atomic Fe–Fe spacing in the 4f “dumbbell” site. The Curie temperature of the compounds Y 2Fe 17, Y 2Fe 15.3Al 1.7 and Y 2Fe 15.3Si 1.7 is proportional to the atomic Fe–Fe spacing in the “dumbbell” site.

Stability of the Anomalous Large-Void CoSn Structure

The crystal structure of CoSn represents a highly peculiar intermetallic structure type because of the presence of a large void and highly nonspherically coordinated tin atoms. Voids in crystal structures of intermetallic compounds are most unusual and always give rise to speculations whether the observed phase is the ground state or not. Here we examine this problem by means of ab initio calculations and show that the void structure of CoSn is indeed the stable phase. With pressure we predict the following sequence of structural transformations: CoSn type $\ensuremath{\rightarrow}$ FeSi type $\ensuremath{\rightarrow}$ CsCl type. The structural properties of CoSn are understood in terms of competition between covalent and metallic bonding in the system.

Magnetic anisotropy and crystal structure of intermetallic compounds of the ThMn12 structure

Intermetallic compounds of the type RE(TM1−xMx)12 with RE=Y, Er; TM=Fe, Co; M=Si, Ti, V of the ThMn12 tetragonal crystal structure have been studied by the singular point detection technique and high-resolution neutron powder diffraction in order to (a) evaluate both the rare-earth and transition-metal sublattice contributions to the magnetocrystalline anisotropy, (b) compare the Fe and Co anisotropies in the ThMn12 structure, and (c) to verify the existence of any preferential entrance in the transition metal sublattice for various stabilizing ions. The transition metal anisotropy is of the same type (Fe axial, Co planar) and magnitude as in RE2Fe14B compounds. However, there is no anomalous temperature behavior of the anisotropy field Ha. With decreasing temperature, the value of Ha increases from 21 kOe at 293 K to 37 kOe at 78 K in YFe11Ti. Similar values are obtained for other Fe-based compounds. The contribution of Er to the anisotropy is found to be surprisingly low. The anisotropy field of ErFe11Ti varies from 24 kOe at 293 K to 63 kOe at 100 K. The observed low values of the Curie temperatures in these compounds appears once again to limit their use in possible applications. Neutron powder diffraction shows that the 8j and 8f sites of the ThMn12 structure are virtually fully occupied by Fe, while the 8i site is partially occupied by Fe and V in YFe10V2.