The crystal structure of WAl12, MoAl12and (Mn, Cr)Al12

Adam, J.; Rich, Jordi

doi:10.1107/s0365110x54002514

Cited by 128 publications

(25 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7͒. Initially the Al 12 Mo appears ͑space group I m 3, 30 aϭb ϭcϭ7.574 Å͒, followed at 600°C by the complete disappearance of fcc Al to give the Al 8 12 Mo and unreacted bcc Mo. As expected, the lattice parameters values are larger than those reported in the literature, since the latter refer to room-temperature measurements.…”

Section: B As-milled Powders Versus Annealingcontrasting

confidence: 46%

See 1 more Smart Citation

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

Enzo¹,

Frattini

Canton³

et al. 2000

Journal of Applied Physics

View full text Add to dashboard Cite

The mechanical treatment of a Al 75 Mo 25 mixture of pure elemental powders in a high-energy mixer mill induces partial solid state reactivity and solid solution formation. This is suggested by a quantitative phase evaluation and by the changes of Al lattice parameter carried out with Rietveld analysis of diffraction patterns collected after extended time of processing ͑4, 8, 16, 32, 57, and 78 h͒. The small angle neutron scattering experiments showed that diffusion processes are the rate-controlling step for these solid state reactions. The formation of metastable phases is confirmed by in situ neutron diffraction annealing experiments on selected as-milled powders. In the specimen mechanically alloyed for 4 h, Al 12 Mo phase is formed at 590°C ͑below the aluminum melting point͒. Soon after this temperature, the remaining Al is consumed to form the Al 8 Mo 3 phase. In the alloy mechanically treated for 32 h, the Al 12 Mo phase appears after annealing at 430°C, while the Al 8 Mo 3 phase is found at 493°C. After the disappearance of Al 12 Mo phase ͑500°C͒, the solid state reaction proceeds to form a new tetragonal Al 3 Mo phase, not reported in the equilibrium phase diagram. In the specimen mechanically treated for 57 h, the total formation of Al 8 Mo 3 is recorded at 430°C. Conversely, in the powder ball milled for 78 h, the Al 8 Mo 3 phase appears at 390°C and coexists with tetragonal Al 3 Mo.

show abstract

Section: B As-milled Powders Versus Annealingcontrasting

confidence: 46%

“…This intermetallic, isostructural with Al 12 W, is the first-order approximant for describing the relationship between icosahedral quasicrystals and their related crystalline structures. 30,33 This point has been discussed separately in another paper. 34 Annealing of the specimen after 57 h of MA ͑Fig.…”

Section: B As-milled Powders Versus Annealingmentioning

confidence: 96%

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

Enzo¹,

Frattini

Canton³

et al. 2000

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…It can also be considered as a filled WAll2-type structure (Adam & Rich, 1954) where La and P correspond to W and A1 and Fe occupies octahedral P interstices which are empty in WAll2. The derivation of the three structure types from the ReO a and CaTiO3-type structures is summarized in Fig.…”

Section: Geometric Relationsmentioning

confidence: 99%

LaFe₄P₁₂ with filled CoAs₃-type structure and isotypic lanthanoid–transition metal polyphosphides

Jeitschko¹,

Braun²

1977

Acta Crystallogr B Struct Sci

572

288

View full text Add to dashboard Cite

The new compound LaFe4Pl2 was prepared by reaction of LaP and Fe powders with red P in evacuated silica tubes. Single crystals of LaFe4P~2 were obtained by reaction of the elemental components in molten Sn. They are cubic, space group Im3, a = 7.832 A, Z = 2. The structure was determined from single-crystal counter data by Patterson and Fourier methods and refined to R = 0.028 for 193 unique structure factors. It represents a new structural type which can be derived from the CoA% and WAlj2-type structures by filling the (somewhat distorted) icosahedral and octahedral voids with La and Fe atoms respectively. The P atoms are coordinated by two Fe and two P atoms forming a distorted tetrahedron augmented by a La atom outside one face of that tetrahedron. In the polyanionic IFe4Pj2 ]3-framework the P-P bonding distances are somewhat expanded, to accommodate the large La 3÷ cation, which in turn has shorter La-P distances than would be expected from the La-P distances in LaP, LaP 2, and LaP 5. The new compounds LnFe4P~2 (Ln = Ce, Pr, Nd, Sm, Eu), LnRu4P~2 (Ln = La, Ce, Pr, Nd, Eu), and LnOs4P.2 (Ln = La, Ce, Pr, Nd) are isotypic with LaFe4P~2. Their lattice constants indicate valencies IV and II for Ce and Eu, respectively, in the compounds. In CeFe4P~2 the polyanion I FeP 31-is isoelectronic and isostructural with CoP 3.

show abstract

“…The dispersoid system was seen to develop through the sequence solid solution --~ I phase --~ a phase --~ All2Mn with characteristic orientation relationships between the different structures (Hansen, Gj0nnes & Andersson, 1989) (Table 1). The stable phase All2Mn (Adam & Rich, 1954), which appears after prolonged annealing, has a body-centred cubic arrangement of 13-atom icosahedra with Mn in the centre. Electron-microscope observations indicated that AltEMn was nucleated on a-phase particles, with a definite orientation relationship.…”

Section: Introductionmentioning

confidence: 99%

Approximants and Intermediate Stages during Transformation from a Quasicrystalline to a Crystalline Phase in an Al–Mn–Si Alloy

Hansen¹,

Gjønnes²

1996

Acta Cryst Sect A

View full text Add to dashboard Cite

In precipitate particles formed by heat treatment of industrially cast Al-(1.8-1.6wt%)Mn alloys, a sequence of stages intermediate between the quasicrystalline I phase and the cubic a-A1MnSi phase have been found. Their electron diffraction patterns and images can be interpreted in terms of faults on { 110}~ planes, with a fault vector [350]/16 or [iTO]/2T 2, where 7-= 1.618 is the golden mean. A lattice generated by such faults on every (110)~ plane has as its unit cell a prolate rhombohedron (a') that is complementary to the oblate rhombohedron (a) that describes the packing of the MacKay icosahedra in a-A1MnSi. Domains of this new lattice have been observed. Based on the two rhombohedra, a cubic Pa3 structure model (a") with cell dimension 7-times aA1MnSi and nearest-neighbour intericosahedral vectors along all threefold axes of the icosahedron is proposed as a second approximant to the I phase in the system, with a-A1MnSi as the first approximant. Calculations of diffraction patterns and Patterson sections are presented as support for this proposal.

show abstract

The crystal structure of WAl₁₂, MoAl₁₂and (Mn, Cr)Al₁₂

Cited by 128 publications

References 0 publications

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

LaFe₄P₁₂ with filled CoAs₃-type structure and isotypic lanthanoid–transition metal polyphosphides

Approximants and Intermediate Stages during Transformation from a Quasicrystalline to a Crystalline Phase in an Al–Mn–Si Alloy

Contact Info

Product

Resources

About

The crystal structure of WAl12, MoAl12and (Mn, Cr)Al12

Cited by 128 publications

References 0 publications

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

Neutron diffraction study of mechanically alloyed and in situ annealed Al75Mo25 powders

LaFe4P12 with filled CoAs3-type structure and isotypic lanthanoid–transition metal polyphosphides

Approximants and Intermediate Stages during Transformation from a Quasicrystalline to a Crystalline Phase in an Al–Mn–Si Alloy

Contact Info

Product

Resources

About

The crystal structure of WAl₁₂, MoAl₁₂and (Mn, Cr)Al₁₂

LaFe₄P₁₂ with filled CoAs₃-type structure and isotypic lanthanoid–transition metal polyphosphides