57Fe Mössbauer isomer shifts in random face-centered cubic Fe–Ni alloys: Experiment versus electronic structure calculations

1992 ◽  
Vol 70 (12) ◽  
pp. 1241-1243 ◽  
Author(s):  
D. G. Rancourt ◽  
J. Y. Ping ◽  
M.-Z. Dang
Keyword(s):  
Tight Binding ◽  
Stability Limit ◽  
Quantitative Agreement ◽  
Face Centered Cubic ◽  
Linear Variation ◽  
Ni Alloys ◽  
Volume Dependence ◽  
Experiment Versus ◽  
Face Centered ◽  
Structure Calculations

Measured 57Fe-isomer shifts for face-centered cubic FeyNi1−y alloys show a linear variation with ∂1S/∂y = +0.10 mm s−1 up to [Formula: see text] followed by a plateau at [Formula: see text], up to the structural stability limit at [Formula: see text]. This is in disagreement with recent ab initio calculations, however, the increase at [Formula: see text] is in quantitative agreement with an older modified tight-binding approach in which the increase arises from an atomic volume dependence. The plateau is an anomaly that sets in at the same composition as that at which the saturation moments start to deviate from the Slater–Pauling curve.

scholarly journals Relativistic Effects on the Equation-of-State of the Light Actinides

2005 ◽  
Vol 893 ◽  
Author(s):  
Alexander Landa ◽  
Per Söderlind
Keyword(s):  
Electronic Structure ◽  
Equation Of State ◽  
Density Functional ◽  
Relativistic Effects ◽  
Model Systems ◽  
Face Centered Cubic ◽  
Electronic Structure Methods ◽  
The Face ◽  
Face Centered ◽  
Structure Calculations

AbstractThe effect of the relativistic spin-orbit (SO)interaction on the bonding in the early actinides has been investigated by means of electronic-structure calculations. Specifically, the equation of state (EOS) for the face-centered cubic (fcc) model systems of these metals has been calculated from the first-principles density-functional (DFT) theory. Traditionally, the SO interaction in electronic-structure methods is implemented as a perturbation to the Hamiltonian that is solved for basis functions that explicitly do not depend on SO coupling. Here this approximation is shown to compare well with the fully relativistic Dirac treatment. It is further shown that SO coupling has a gradually increasing effect on the EOS as one proceeds through the actinides and the effect is diminished as density increases.

Stability and Structural Transition of Gold Nanowires under Their Own Surface Stresses

2004 ◽  
Vol 854 ◽  
Author(s):  
Ken Gall ◽  
Michael Haftel ◽  
Jiankuai Diao ◽  
Martin L. Dunn ◽  
Noam Bernstein ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Tight Binding ◽  
Gold Nanowires ◽  
Face Centered Cubic ◽  
First Principle ◽  
Local Energy Minimum ◽  
Surface Stresses ◽  
Embedded Atom ◽  
Theoretical Approaches ◽  
Face Centered

ABSTRACTFirst-principle, tight binding, and semi-empirical embedded atom calculations are used to investigate a tetragonal phase transformation in gold nanowires. As wire diameter is decreased, tight binding and modified embedded atom simulations predict a surface-stress-induced phase transformation from a face-centered-cubic (fcc) <100> nanowire into a body-centered-tetragonal (bct) nanowire. In bulk gold, all theoretical approaches predict a local energy minimum at the bct phase, but tight binding and first principle calculations predict elastic instability of the bulk bct phase. The predicted existence of the stable bct phase in the nanowires is thus attributed to constraint from surface stresses. The results demonstrate that surface stresses are theoretically capable of inducing phase transformation and subsequent phase stability in nanometer scale metallic wires under appropriate conditions.

TEM Studies Of Devitrification Products in Al-Gd-Ni-(Fe) Alloys.

2003 ◽  
Vol 806 ◽  
Author(s):  
A. L. Vasiliev ◽  
M. Aindow ◽  
M. J. Blackburn ◽  
T. J. Watson
Keyword(s):  
Electron Microscopy ◽  
Metallic Glasses ◽  
Rhombohedral Phase ◽  
Face Centered Cubic ◽  
Ni Alloys ◽  
Transmission Electron ◽  
Present Complex ◽  
Fe Alloys ◽  
Face Centered ◽  
Complex Faulting

ABSTRACTMetallic glasses can form in certain Al-Gd-Ni alloys. Devitrificaion occurs on subsequent heating to intermediate temperatures and although some phases form as expected the crystal structures of others are less certain. This paper presents a summary of transmission electron microscopy (TEM) data acquired from four devitrified Al-Gd-Ni(-Fe) alloys. It is shown that the alloys exhibit nanocrystalline microstructures consisting of face-centered-cubic α-Al, binary Al3Gd, and ternary phases. An Al-(Gd,Fe)-Ni phase forms as rods and exhibits the orthorhombic Al19Ni5Gd3 structure. Plates of the rhombohedral phase Al23(Ni,Fe)6Gd4 are also present. Complex faulting is observed in both ternary phases.

Effect of Cobalt Concentration on the Microstructure of Nickel-Cobalt Alloy Deposits

2014 ◽  
Vol 887-888 ◽  
pp. 749-752 ◽  
Author(s):  
Yusrini Marita ◽  
Ridwan
Keyword(s):  
Copper Substrate ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Cobalt Alloy ◽  
Cobalt Sulfate ◽  
X Ray ◽  
Ni Alloys ◽  
Nickel Cobalt ◽  
Face Centered ◽  
Co Alloys

Nickel-cobalt alloy deposits were prepared on copper substrate by electrochemical deposition at various cobalt concentrations in electrolytic solution of 0, 6, 12, 18 and 24 g l-1. The deposition was performed at current density of 30 mA/cm2. X-ray diffraction measurements confirmed that all nickel-cobalt alloy films formed have face-centered cubic structure. EDS studies showed that Co content in Ni-Co alloys increased with the increase of cobalt sulfate concentration in the solution. It can be suggested that increasing concentration of co sulfate is the reason for an increase in activity of cobalt ion. The investigations on the electrodeposited Co-Ni alloys have been shown that their microstructure and surface morphology were found to depend strongly on the Co content in the Ni-Co alloy deposited.

scholarly journals Nanoscale twinning in Fe–Mn–Al–Ni martensite: a backscatter Kikuchi diffraction study

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Peter D. B. Fischer ◽  
Stefan Martin ◽  
Alexander Walnsch ◽  
Martin Thümmler ◽  
Mario J. Kriegel ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Diffraction Study ◽  
Face Centered Cubic ◽  
Ni Alloys ◽  
Heat Treated ◽  
Iron Based ◽  
Face Centered ◽  
Ice Water ◽  
Interstitial Elements

Iron-based Fe–Mn–Al–Ni shape-memory alloys are of rather low materials cost and show remarkable pseudoelastic properties. To further understand the martensitic transformation giving rise to the pseudoelastic properties, different Fe–Mn–Al–Ni alloys have been heat treated at 1473 K and quenched in ice water. The martensite, which is formed from a body-centred cubic austenite, is commonly described as face-centered cubic (f.c.c.), even though there are also more complex, polytypical descriptions of martensite. The presently studied backscatter Kikuchi diffraction (BKD) patterns have been evaluated, showing a structure more complex than simple f.c.c. This structure can be described by nanoscale twins, diffracting simultaneously in the exciting volume. The twinned structure shows a tetragonal distortion, not uncommon for martensite in spite of the lack of interstitial elements. These features are evaluated by comparing the measured BKD patterns with dynamically simulated ones.

High-pressure melting curves of FCC metals Ni, Pd and Pt with defects

2019 ◽  
Vol 33 (25) ◽  
pp. 1950300
Author(s):  
Nguyen Quang Hoc ◽  
Tran Dinh Cuong ◽  
Bui Duc Tinh ◽  
Le Hong Viet
Keyword(s):  
High Pressure ◽  
Theoretical Calculations ◽  
Stability Limit ◽  
Face Centered Cubic ◽  
Fcc Metals ◽  
Melting Curves ◽  
Melting Properties ◽  
Pressure Melting ◽  
Face Centered ◽  
Statistical Moment Method

The high-pressure melting curves of defective metals Ni, Pd and Pt with face-centered cubic structure have been studied up to 100 GPa by using the statistical moment method. Our melting theory is based on the absolute stability limit for crystalline state. The effects of pressure and vacancies on the melting properties of Ni, Pd and Pt have been considered. These obtained results are consistent with previous experiments and other theoretical calculations.

scholarly journals Magnetic and thermodynamic properties of face-centered cubic Fe–Ni alloys

2014 ◽  
Vol 16 (30) ◽  
pp. 16049 ◽  
Author(s):  
M. Yu. Lavrentiev ◽  
J. S. Wróbel ◽  
D. Nguyen-Manh ◽  
S. L. Dudarev
Keyword(s):  
Thermodynamic Properties ◽  
Face Centered Cubic ◽  
Ni Alloys ◽  
Face Centered

Molybdenum effect on Fe–Cr–Ni-alloy elastic constants

1988 ◽  
Vol 3 (1) ◽  
pp. 40-44 ◽  
Author(s):  
H. M. Ledbetter ◽  
S. A. Kim
Keyword(s):  
Bulk Modulus ◽  
Elastic Constants ◽  
Poisson Ratio ◽  
Face Centered Cubic ◽  
Electron Theory ◽  
Shear Moduli ◽  
Ni Alloys ◽  
Ni Alloy ◽  
Face Centered ◽  
Mo Content

This study involved the ultrasonic measurement of the polycrystalline elastic constants of six face-centered-cubic Fe–Cr–Ni alloys, nominally Fe–19Cr–12Ni (at. %). In these alloys, Mo content ranged up to 2.4 at. %. Molybdenum lowers the Young and shear moduli, and it raises the Poisson ratio. Against expectation (because it increases volume), Mo raises the bulk modulus. Qualitatively, the results show that Ni raises the bulk modulus and Poisson ratio; but Ni lowers the Young and shear moduli. (Nickel decreases the alloy's atomic volume.) The discussion includes existing models based on 3d-electron theory.

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