scholarly journals The intermetallic compound phases of the system aluminium-manganese-zinc

1947 ◽  
Vol 190 (1020) ◽  
pp. 82-101 ◽  
Keyword(s):  
Ternary Eutectic ◽  
Alloy Formation ◽  
Atom Ratio ◽  
X Ray ◽  
Transitional Metals ◽  
Ternary Compounds ◽  
Manganese Zinc ◽  
Metal Atoms ◽  
Transitional Metal ◽  
Ray Methods

The system aluminium-manganese-zinc has been examined in the range 0 to 95 % of zinc, and 0 to 3 % of manganese. Attention was directed only to the constitution of the alloys above the solidus. Using micrographic and X-ray methods, and the chemical analysis of crystals separated from slowly cooled alloys, it has been shown that, according to composition, the phases MnAl 6 , T 1 , MnAl 4 , T 2 , T 3 and MnAl 3 may crystallize as primary constituents. Both MnAl 6 and MnAl 4 dissolve small quantities of zinc; the phases T 1 , T 2 and T 3 are ternary compounds. The phase T 1 is characterized by a ratio of four aluminium atoms to one of combined solutes, and an electron: atom ratio of 1.85, calculated on the basis of the Pauling theory of transitional metals. According to this theory, transitional metal atoms have vacancies for electrons in their atomi orbitals, and the present experiments in conjunction with earlier work suggest that these may be filled up as a consequence of alloy formation. The phases T 2 and T 3 may be represented respectively by the formulae Mn 2 ZnAl 9 and (Mn.Zn 5 Al 11 . MnAl 3 , which can dissolve small quantities of zinc, enters into equilibrium at a ternary eutectic (Zn 95 %, Mn 0.05 %; 378° C) with the primary solid solutions in zinc and aluminium respectively.

scholarly journals The constitution of the aluminium-rich aluminium-cobaltcopper alloys, with special reference to the role of transitional metals in alloy formation

1949 ◽  
Vol 197 (1050) ◽  
pp. 321-335 ◽  
Keyword(s):  
Solid Solution ◽  
Ternary Compound ◽  
Copper Alloys ◽  
Primary Crystallization ◽  
Alloy Formation ◽  
Atom Ratio ◽  
Transitional Metals ◽  
Ternary Compounds ◽  
Electron Atom

An experimental investigation of aluminium-rich aluminium-cobalt-copper alloys has shown that, as in the alloys of alumiinium and copper with nickel and iron respectively, a ternary compound, in addition to the phases Co 2 Al 9 and CuAl 2 , enters into equilibrium with the primary solid solution. Isothermal sections of the ternary model have been established at 530° and 500° C; the field in which the solid solution, α , and the ternary compound, T (CoCu), are in equilibrium is very narrow, while the ( α + Co 2 Al 9 ), ( α + Co 2 Al 9 + T (CoCu)) and ( α + T (CoCu)+CuAl 2 ) phase fields are relatively extensive. The presence of T (CoCu), and its formation peritectically from Co 2 Al 9 , have been confirmed by further experiments on solid and semi-liquid alloys and, from the examination of slowly cooled alloys, the appropriate fields of primary crystallization have been determined. The composition range in which T (CoCu) separates as primary crystals is restricted, and, for this and other reasons, pure samples of T (CoCu) cannot be obtained for analysis. Extrapolation of the accurately established ( α + T (CoCu) + CuAl 2 )/( α + T (CoCu)) and ( α + T (CoCu) + CuAl 2 )/( T (CoCu) + CuAl 2 ) boundaries, however, showrs that the homogeneity range of T (CoCu) includes the composition Co 2 Cu 5 Al 16 . The solubility of copper in Co 2 Al 9 does not exceed 1·44% at 570° C. In discussion, it is showm that the ternary compounds NiCu 3 Al 6 and FeCu 2 Al 7 occur at the same electron: atom ratio, according to the authors’ theory of the role of transitional elements in alloy formation. The compound T (CoCu) forms a third member of the same series and is probably of the ideal composition Co 2 Cu 5 Al 13 . The results support the hypothesis of absorption of electrons by transitional metal atoms present in aluminium-rich alloys, and also that the occurrence of ternary compounds is influenced to a marked degree by the electron: atom ratio.

Intermetallic compounds in ternary aluminium-rich alloys containing transitional metals

1951 ◽  
Vol 205 (1080) ◽  
pp. 103-118 ◽  
Keyword(s):  
Ternary Compound ◽  
Solid Solutions ◽  
Atom Ratio ◽  
Atomic Orbitals ◽  
Transitional Metals ◽  
Ternary Compounds ◽  
Iron Silicon ◽  
Electron Atom ◽  
Transitional Metal ◽  
Silicon System

Several investigations have now been made of the constitutions of ternary aluminium-rich alloys containing transitional metal solutes. Consideration of the results obtained has led to the conclusion that in aluminium-rich alloys, the transitional metal atoms may accept electrons from the structure as a whole, and that the ternary compounds formed have many of the characteristics of electron compounds. Although the acceptance of electrons may be understood in terms of the completion of the 3 d band of the transitional metal, consideration of the Brillouin zone structures of Co 2 Al 9 , Co 2 Al 5 and NiAl 3 suggests, empirically, that the numbers of electrons accepted per atom are greater than the band theory would indicate, and are more nearly equal to the vacancies in the 'atomic orbitals’ postulated in the Pauling theory of transitional metals. Further information with regard to the alloying characteristics of transitional metals has been sought by investigating ternary alloys of aluminium and silicon with chromium, manganese, iron, cobalt and nickel. The results are discussed in the present paper. Assuming acceptance of electrons by the transitional metals to extents given by the vacancies in the 'atomic orbitals’ postulated by Pauling, it is found that the ternary compound of higher electron: atom ratio in the aluminium-chromium-silicon system has a similar electron concentration to that of the ternary compound of lower electron: atom ratio in the aluminium-manganese-silicon system. This behaviour is repeated for the systems aluminium-manganese-silicon and aluminium-iron-silicon; in this case the compounds involved (α(AlFeSi) and α(AlMnSi)) are isomorphous and form uninterrupted solid solutions with each other. The compound of higher electron: atom ratio in the system aluminium-iron-silicon (β(AlFeSi)) has no counterpart in the aluminium-cobalt-silicon system, but Co 2 Al 9 dissolves silicon until the electron: atom ratio is raised sufficiently to overlap the range of electron: atom ratios characteristic of β(AlFeSi). As the number of vacancies for electrons per atom of transitional metal decreases, the ternary compounds formed tend to move to progressively higher ranges of electron: atom ratio. These results are discussed in relation to previous work, and support the general hypothesis of acceptance of electrons by transitional metals. Of particular significance are the observations that silicon and nickel both dissolve in Co 2 Al 9 until the same maximum electron: atom ratio is reached; that α(AlMnSi) and α(AlFeSi) form uninterrupted solid solutions and, according to the hypothesis, have similar electron:atom ratios; and that structural relationships exist between various compounds whose electron: atom ratios are similar.

The system iron-gallium

1965 ◽  
Vol 286 (1405) ◽  
pp. 141-157 ◽  
Keyword(s):  
Equilibrium Diagram ◽  
Size Factor ◽  
Ordered Structure ◽  
Concentration Effects ◽  
Great Stability ◽  
Atom Ratio ◽  
X Ray ◽  
Cscl Type ◽  
Group D ◽  
Ray Methods

The equilibrium diagram of the system Fe-Ga has been determined by a combination of thermal analysis, microscopical, and X-ray methods. The system is of the γ loop type, and gallium dissolves in αδ iron up to a maximum of 48.4 at. %. In contrast to the system Fe-Al, there are no superlattices in the b.c.c. solid solution, but in the region of 30 at. % Ga, f.c.c. phases of slightly variable composition are formed from the b.c.c. phase, and these have the Cu 3 Au type of ordered structure at low temperatures, and a random f.c.c. structure at high temperatures. It is significant that metastable f.c.c. structures have been reported in the system Fe-Al, and it is probable that the more favourable size factor in the system Fe-Ga is responsible for the greater stability of the close-packed f.c.c. phase. At higher proportions of gallium, intermetallic compounds Fe 3 Ga 4 and FeGa 3 have been established, and the crystal structure of the latter has been determined, and is similar to that of CoGa 3 (tetragonal space group D 8 2d - P 4 n 2 ) but with slightly different positions of the atoms in the unit cell. The structures of alloys of Fe, Co, and Ni with Zn, Ga, and Al are discussed. The differences are ascribed to (1) the greater tendency of Ni and Co to fill the 3 d shell, as compared with Fe, (2) the more electropositive nature of Al as compared with Ga. The ordered b.c.c. phases are stabilized both by electron concentration effects, and by superlattice factors which favour a structure in which an atom has neighbours of the opposite kind. The great stability of the NiAl and CoAl b.c.c. phases (CsCl type) results from the fact that if a transition metal has a zero valency, it is only with a 3-valent solute that the equiatomic ratio gives the electron: atom ratio 3/2 which favours the b.c.c. structure, and so permits the formation of the CsCl arrangement in which each atom is surrounded by eight of the opposite kind.

AB2X2-Verbindungen im CaAl2Si2-Typ, V[1] Zur Struktur der Verbindungen CaMn2P2, CaMn2As2, SrMn2P2 und SrMn2As2 / AB2X2-Compounds with the CaAl2Si2 Structure, V [1] The Crystal Structure of CaMn2P2, CaMn2As2, SrMn2P2, and SrMn2As2

1978 ◽  
Vol 33 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Albrecht Mewis
Keyword(s):  
Crystal Structure ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Ternary Compounds ◽  
Structure Space ◽  
Ray Methods

Abstract Four ternary compounds with the formulas CaMn2P2, CaMn2As2, SrMn2P2, and SrMn2As2 have been prepared and investigated by X-ray methods. They are isotypic and crystallize trigonally in a CaAl2Si2-type structure (space group P3̅m 1-D33d) with the lattice constants: CaMn2P2 a = 4,096 ± 0,001 Å, c = 6,848 ± 0,002 Å, CaMn2As2 a = 4,239 ± 0,001 Å, c = 7,027 ± 0,003 Å, SrMn2P2 a = 4,168 ± 0,001 Å, c = 7,132 ± 0,001 Å, SrMn2As2 a = 4,306 ± 0,001 Å, c = 7,315 ± 0,001 Å. The lattice constants of BaMn2P2 and BaMn2As2 are given

Komplexe des Typs [MCl4(SEt2)2] mit M = Mo und W. Kristallstrukturen, NMR-Spektren und magnetisches Verhalten/[MCl4(SEt2)2] Complexes with M = Mo and W. Crystal Structures, NMR Spectra, and Magnetic Behaviour

1995 ◽  
Vol 50 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Peter Dierkes ◽  
Gerlinde Frenzen ◽  
Sigrid Wocadlo ◽  
Werner Massa ◽  
Stefan Berger ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Nmr Spectra ◽  
Magnetic Behaviour ◽  
Triclinic Space Group ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Metal Atoms ◽  
Ray Methods ◽  
C Nmr

The crystal structures of the thioether complexes [MCl4(SEt2)2] with M = Mo and W have been solved by X-ray methods. Both compounds crystallize isotypically in the triclinic space group P1̄ with two formula units per cell unit. The metal atoms are octahedrally coordinated by four chlorine atoms and by the two sulfur atoms of the thioether molecules in transposition (symmetry Ci) with bond lengths (average): Mo-Cl 233.1, Mo-S 253.4, W-Cl 233.1, and W-S 251.7 pm. Both complexes were also characterized by 1H and 13C NMR spectroscopy as well as by measurement of the magnetic susceptibilities in the temperature range from 1.8 to 350 K.

scholarly journals NOTIZEN: Mg6Ni16As7 - eine neue G-Phase / Mg6Ni16As7 - a New G Phase

1995 ◽  
Vol 50 (8) ◽  
pp. 1275-1276 ◽  
Author(s):  
Viktor Keimes ◽  
Albrecht Mewis
Keyword(s):  
Single Crystal ◽  
Type Structure ◽  
X Ray ◽  
Ternary Compounds ◽  
Ray Methods

Mg6Ni16As7 (F m 3m ; a = 11.479(1) Å; Z = 4) was prepared by heating a mixture of the elements and investigated by means of single crystal X-ray methods. The arsenide crystallizes in a modified Th6Mn23 type structure, similar to many ternary compounds of the composition A6M16X7, called G phases.

Synthese und Kristallstrukturen von Seltenerdmetall-Antimoniden des Palladiums / Synthesis and Crystal Structures of Antimonides of Rare-Earth Metals and Palladium

2006 ◽  
Vol 61 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Anette Imre ◽  
Albrecht Mewis
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Three Dimensional ◽  
Earth Metal ◽  
Type Structure ◽  
X Ray ◽  
Metal Atoms ◽  
New Compounds ◽  
Ray Methods ◽  
The Rare Earth

The new compounds Pr3Pd6Sb5 (a = 13.442(3), b = 4.442(1), c = 9.994(2) Å ), Nd3Pd6Sb5 (a = 13.412(3), b = 4.431(1), c = 9.962(2) Å), and Gd3Pd6Sb5 (a = 13.293(2), b = 4.397(1), c = 9.881(2) Å) are isotypic and crystallize with the Ce3Pd6Sb5 type structure (Pmmn; Z = 2). The rare-earth metal atoms are arranged in form of three pseudo-body-centered subcells, whereas Pd and Sb atoms form a three-dimensional arrangement derived from the well-known ThCr2Si2 and CaBe2Ge2 structures. GdPdSb (a = 4.566(1), c = 7.444(1) Å) and DyPdSb (a = 4.545(1), c = 7.354(1) Å) crystallize with an ordered variant of the CaIn2 type structure (P63mc; Z = 2), also called as LiGaGe type, with slightly puckered hexagon nets of Pd and Sb atoms, which trigonally coordinate each other. In this series a decreasing radius of the rare-earth metal allows a tetrahedral non-metal environment of the Pd atoms and accordingly ScPdSb (a = 6.310(1) Å) forms the MgAgAs type structure (F4̄3m; Z = 4), a filled variant of the sphalerite type. The antimonides were prepared by heating mixtures of the elements at 600 °C and subsequent annealing at 900 - 1100 °C. Their structures have been determined by single-crystal X-ray methods.

Darstellung und Struktur der Verbindungen PrLi2P2, PrLi2As2 und NdLi2As2 / Preparation and Crystal Structure of PrLi2P2, PrLi2As2 and NdLi2As2

1980 ◽  
Vol 35 (10) ◽  
pp. 1322-1323 ◽  
Author(s):  
Herrad-Odilia Fischer ◽  
Hans-Uwe Schuster
Keyword(s):  
Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Ternary Compounds ◽  
Structure Space ◽  
Ray Methods

Abstract Three ternary compounds PrLi2P2, PrLi2As2 and NdLi2As2 have been prepared and investigated by X-ray methods. They are isotypic and crystallize trigonally in the CaAl2Si2-structure (Space group P3̅m1-D3d3) with the follow-ing cell parameters:PrLi2P2: a = 419.6 pm, c = 682.1 pm;PrLi2As2: a = 429.9 pm, c = 696.0 pm;NdLi2As2: a = 428.7 pm, c = 692.2 pm.

The quaternary system aluminium-iron-cobalt-nickel, with reference to the role of transitional metals in alloys

1950 ◽  
Vol 202 (1070) ◽  
pp. 420-438 ◽  
Keyword(s):  
Quaternary System ◽  
Equilibrium Diagram ◽  
Iron Cobalt ◽  
Atom Ratio ◽  
Transitional Metals ◽  
Electron Atom ◽  
Cobalt Nickel ◽  
Metal Atoms ◽  
Iron Nickel ◽  
Electron Compounds

In a previous publication, the results of an investigation of the aluminium-rich portion of the aluminium-iron-nickel equilibrium diagram were reported and interpreted theoretically (Raynor & Pfeil 1946-7 a ). On the basis of this theoretical work, the forms of the previously unknown equilibrium diagrams for the systems aluminium-iron-cobalt and aluminium-cobalt-nickel were deduced, and subsequently verified quantitatively by experiment (Raynor & Pfeil 1946-76; Raynor & Waldron 1948). In the present paper, similar reasoning has been applied to the quaternary aluminium-iron-cobalt-nickel system, and the form of diagram expected compared with experiment. Previous work has suggested that Co 2 Al 9 and the isomorphous FeNiAl 9 are analogous to electron compounds. If the theory be accepted that transitional metal atoms may absorb electrons in aluminium-rich alloys to an extent governed by the vacancies in their atomic orbitals (or 3 d shells), the two compounds have closely similar electron: atom ratios, and both dissolve nickel to the same limiting electron: atom ratio. Co 2 Al 9 will dissolve more iron than FeNiAl 9 ; the reason for this has been discussed. In the quaternary system, it would be expected that a continuous series of solid solutions, of composition (Fe.Co.Ni) 2 Al 9 , would exist between the two compounds, and that the aluminium-rich boundary of the quaternary body in the tetrahedral equilibrium model would be a plane corresponding to a constant proportion of 2 solute atoms to 9 aluminium atoms. It would also be expected that the whole boundary corresponding to saturation of the quaternary body with nickel would occur at a constant electron-atom ratio. These considerations imply that no other phases, apart from FeAl 3 and NiAl 3 (which dissolve relatively small amounts of the other transitional solutes), enter into equilibrium with the aluminium-rich solid solution, and that the liquidus surfaces for FeNiAl 9 and Co 2 Al 9 merge continuously into each other without a break. Further predictions with regard to the form of the equilibrium diagram may also be made, and these are discussed in the paper. The results of the investigation, which are discussed, confirm previous suggestions that the inter-metallic compounds formed by aluminium and transitional metals may, if sufficient aluminium is present, be regarded as analogous to electron compounds, with absorption of electrons by the transitional metal atoms occurring. The theory may be used, in favourable cases, to predict quantitatively the forms of uninvestigated complex equilibrium diagrams. In the present case, equilibrium relationships in a quaternary system have been predicted from those in the three subsidiary ternary systems, two of which were themselves largely predicted as a result of the original theoretical in terpretation of the aluminium-iron-nickel alloys.

AB2X2-Verbindungen im CaAl2Si2-Typ, IV [1] Zur Struktur der Verbindungen CaZn2Sb2, CaCd2Sb2, SrZn2Sb2 und SrCd2Sb2 / AB2X2 Compounds with the CaAl2Si2 Structure, IV [1J The Crystal Structure of CaZn2Sb2, CaCd2Sb2, SrZn2Sb2, and SrCd2Sb2

1978 ◽  
Vol 33 (4) ◽  
pp. 382-384 ◽  
Author(s):  
Albrecht Mewis
Keyword(s):  
Crystal Structure ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Ternary Compounds ◽  
Structure Space ◽  
Ray Methods

Abstract The four ternary compounds CaZn2Sb2, CaCd2Sb2, SrZn2Sb2, and SrCd2Sb2 have been prepared and investigated by X-ray methods. They are isotypic and crystallize trigonally in a CaAl2Si2-type structure (space group P3̅m 1-D33d) with the following constants:CaZn2Sb2 a = 4.441 ± 0.001 Å, c = 7.464 ± 0.002 Å;CaCd2Sb2 a = 4.649 ± 0.001 Å, c = 7.597 ± 0.002 Å;SrZn2Sb2 a = 4.500 ± 0.001 Å, c = 7,716 ± 0.002 Å; SrCd2Sb2 a = 4.709 ± 0.001 Å, c = 7.822 ± 0.003 Å.

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