Transformation from icosahedral phase to body center cubic phase in cut description

1989 ◽  
Vol 6 (10) ◽  
pp. 465-468 ◽  
Author(s):  
Li Fanghua ◽  
Pan Guangzhao ◽  
Cheng Yifan
Keyword(s):  
Icosahedral Phase ◽  
Cubic Phase ◽  
Body Center Cubic ◽  
Body Center

Rapid Thermal Transformation of A-15 Crystal Structure Metallic Thin Films

1995 ◽  
Vol 387 ◽  
Author(s):  
M. J. O'Keefe ◽  
C. L. Cerny
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Physical Vapor Deposition ◽  
Thermal Transformation ◽  
The Body ◽  
Cubic Phase ◽  
Body Centered Cubic ◽  
Body Center Cubic

AbstractPhysical vapor deposition of Group VI elements (Cr, Mo, W) can lead to the formation of a metastable A-15 crystal structure under certain processing conditions. Typically, a thermally induced transformation of the metastable A-15 structure into the equilibrium body centered cubic structure has been accomplished by conventional furnace annealing at T/Tm ≈ 0.3 from tens of minutes to several hours. In this study we report on the use of rapid thermal annealing to transform sputter deposited A- 15 crystal structure tungsten and chromium thin films into body centered cubic films within the same temperature range but at times on the order of one minute. The minimum annealing times and temperatures required for complete transformation of the A-15 phase into the BCC phase varied from sample to sample, indicating that the transformation was dependent on the film characteristics. The electrical resistivity of A-15 Cr and W films was measured before and after rapid thermal annealing and was found to significantly decrease after transformation into the body center cubic phase.

Modulated Structures, Nanocrystals and Quasicrystals in Mg-Zn-Y Alloys

2000 ◽  
Vol 643 ◽  
Author(s):  
Anandh Subramaniam ◽  
S. Ranganathan
Keyword(s):  
Cast Alloy ◽  
Icosahedral Phase ◽  
Cubic Phase ◽  
Nominal Composition ◽  
Modulated Structures

AbstractThe formation of the icosahedral phase, BCC (Body centred cubic) phase and nanocrystals are seen in the as-cast alloy with nominal composition of Mg4Zn94Y2. FCC (face centred cubic) phase and modulated structures are formed in the alloys with higher Y content (10% and 25% Y respectively). These phases are analysed keeping in view their relation to the quasicrystals of the Mg-Zn-Y system.

scholarly journals Dynamical stability of body center cubic iron at the Earth's core conditions

2010 ◽  
Vol 107 (22) ◽  
pp. 9962-9964 ◽  
Author(s):  
W. Luo ◽  
B. Johansson ◽  
O. Eriksson ◽  
S. Arapan ◽  
P. Souvatzis ◽  
...  
Keyword(s):  
Dynamical Stability ◽  
Earth’S Core ◽  
Earth's Core ◽  
Body Center Cubic ◽  
Body Center ◽  
Core Conditions

Approximants to the icosahedral and decagonal phases in the Al–Cu–Cr system

1991 ◽  
Vol 6 (8) ◽  
pp. 1641-1649 ◽  
Author(s):  
S. Ebalard ◽  
F. Spaepen
Keyword(s):  
Electron Diffraction ◽  
Icosahedral Phase ◽  
Lattice Parameters ◽  
Cubic Phase ◽  
Decagonal Phase ◽  
Bcc Lattice ◽  
Selected Area Electron Diffraction ◽  
Phase Ordering ◽  
Cr System

A 1/1-type approximant to the AlCuCr icosahedral phase and approximants to a decagonal phase have been found in an as-cast Al65Cu20Cr15 ingot. Selected area electron diffraction indicates that the 1/1-type approximant consists of Mackay icosahedra arranged on a bcc lattice, similar to the α-AlMnSi cubic phase. Ordering of the glue atoms produces a base-centered orthorhombic superstructure, making the overall structure monoclinic P2/m, with lattice parameters a = 12.6 Å, c = 17.92 Å, and α = 90°.

Atom Clusters In A 2/1 Cubic Approximant Phase For Understanding The Structures Of Icosahedral Phases

1998 ◽  
Vol 553 ◽  
Author(s):  
K. HIRAGA
Keyword(s):  
Icosahedral Phase ◽  
The Body ◽  
Cubic Phase ◽  
Icosahedral Quasicrystal ◽  
Icosahedral Symmetry ◽  
Atom Cluster ◽  
Atom Clusters ◽  
Simple Cubic ◽  
Icosahedral Phases ◽  
Rotational Direction

AbstractTwo types of atom clusters found in the β-(A1PdMnSi) cubic phase, referred to as a 2/1 crystalline approximant, with a composition of approximately Al70Pd23Mn6Si1 which is near to the composition Al72Pd20Mn8 of the icosahedral phase, are discussed in detail for understanding the structure of the Al-Pd-Mn icosahedral phase. A large dodecahedral atom cluster located at the body-centered position can be divided into 19 atom shells with approximately icosahedral symmetry, and a dodecahedron of the 12th shell internally touches the surface of the cubic unit cell with a lattice constant of 2.0211 nm. At each vertex of the dodecahedron, a small icosahedral atom cluster consisting of 12 Al atoms surrounding a central Pd atom is located. The dodecahedron is connected to each other by edge-sharing, namely by sharing two small icosahedral atom clusters, along the twofold rotational direction, and forms a simple-cubic packing of the atom cluster in the β-(AlPdMnSi) cubic phase. Another atom cluster located at the origin fills up gaps of the simple-cubic packing of the large dodecahedral atom cluster. By using the dodecahedral and bridging atom clusters, the structure of the Al-Pd-Mn icosahedral quasicrystal is discussed.

On the new structural phases in Al65Cu20Cr15 quasicrystalline alloy

1995 ◽  
Vol 10 (8) ◽  
pp. 1905-1912 ◽  
Author(s):  
Varsha Khare ◽  
N.P. Lalla ◽  
R.S. Tiwari ◽  
O.N. Srivastava
Keyword(s):  
Metastable Phase ◽  
Structural Characteristics ◽  
Icosahedral Phase ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Structural Variants ◽  
Simple Cubic ◽  
Face Centered ◽  
Specific Orientation

The quasicrystalline (qc) alloy Al65Cu20Cr15, unlike its Ru- and Fe-bearing counterparts like Al65Cu20Ru15 and Al65Cu20Fe15, is a metastable phase. This qc alloy has been shown to possess several structural variants and curious structural characteristics. We have investigated the qc alloy Al65Cu20Cr15 with special reference to the possible occurrence of new structural variants. TEM exploration of the as-quenched qc alloy has indeed revealed the existence of several new phases. These are (i) body-centered cubic (bcc) (a = 12.60 Å, disordered) and simple cubic (s.c.) (a = 12.60 Å, ordered), which are the 1/1 approximants of the primitive icosahedral phase (i phase); (ii) a twice order-induced modulated cubic phase (bcc, a = 25.20 Å) which has been shown to correspond to 1/1 approximant of the ordered i phase [i.e., face-centered icosahedral (FCI)]; and (iii) real crystalline bcc (a = 8.90 Å) and face-centered cubic (fcc) (a = 17.98 Å) phases possessing a specific orientation relationship with the icosahedral matrix phase. Tentative structural models showing the interrelationships between the bcc/fcc phases have been outlined.

scholarly journals Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys

Batteries ◽  
2016 ◽  
Vol 2 (3) ◽  
pp. 22 ◽  
Author(s):  
Hao-Ting Shen ◽  
Kwo-Hsiung Young ◽  
Tiejun Meng ◽  
Leonid Bendersky
Keyword(s):  
Grain Boundary ◽  
Metal Hydride ◽  
Body Center Cubic ◽  
Body Center ◽  
Metal Hydride Alloys ◽  
Multi Phase

scholarly journals Nanofabrication of Iron-Cobalt (FeCo) Alloy by Sol-gel Method

2021 ◽  
Vol 1 (1) ◽  
pp. 111-114
Author(s):  
Majid Farahmandjou ◽  
Parastoo Khalili
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Sem Analysis ◽  
The Body ◽  
X Ray Diffraction ◽  
Body Center Cubic ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Bcc Structure ◽  
Body Center

Background and Introduction: Metal oxides (MOs) have been extensively used in a large range of engineering and medical applications. Methods: FeCo nanoparticles (NPs) were successfully synthesized by the solgel method in the presence of a powerful reducing agent-sodium borohydride (NaBH4). The structure, morphology, and optical properties of NPs were analyzed by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) at room temperature. Results: The XRD spectrum showed the body center cubic (BCC) structure of the samples after heat treatment at 500 °C. The SEM analysis exhibited that the particle size of as-synthesized and annealed samples was approximately 40 nm and 22 nm, respectively. Conclusion: The TEM investigations showed the rod-shaped sample of annealed NPs. The optical studies of the FTIR analysis revealed the starching bound of Fe-Co at the frequencies of 673 cm-1, 598 cm-1, and 478 cm-1.

Preparations Effects on Amorphous/Nanocrystal Ni-Mo Alloys Structure and Properties

2011 ◽  
Vol 217-218 ◽  
pp. 21-26
Author(s):  
Ning Li ◽  
Cheng Hui Gao ◽  
Guang Ming Cheng
Keyword(s):  
Chemical Properties ◽  
Xrd Analysis ◽  
Dimensional Structure ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Forming Mechanism ◽  
Body Center Cubic ◽  
The Face ◽  
Body Center ◽  
Binary Compounds

Ni-Mo alloys have been studied as a prospected cathode for its higher hydrogen evolution reaction properties than other binary compounds. The eletrodeposition parameters and its effects have been investigated in forming Ni-Mo alloys in the present study by measuring the structure and properties of deposits. The forming mechanism of Ni-Mo amorphous deposit is discussed from point of the elements component of view. The X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) microstructures show that the molybdenum content in the deposit is increased with the molybdate concentration increase, and the deposit structure can be parted several stages- nanocrystal, nanocrystal/amorphous, amorphous, crystalline, or the mixed configuration due to the variation of Mo atom content. The forming mechanism of the deposit of Ni-Mo alloys is attributable to the repulsive aggradations as of the molybdenum chemical properties and electronic shell structure. When the atom rate of Ni/Mo is higher than 0.35, the deposit is the face center cubic (fcc) configuration, while lower than 0.35, the deposit is the monoclinic hexagon crystalloid configuration or body center cubic (bcc) dimensional structure.

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