scholarly journals Nuclear Gamma Resonance Study of the Ir —Fe and Ir —Ni Alloy Systems

1971 ◽  
Vol 26 (3) ◽  
pp. 343-352 ◽  
Author(s):  
R.L. Mössbauer ◽  
M. Lengsfeld ◽  
W. Von Lieres ◽  
W. Potzel ◽  
T. Teschner ◽  
...  
Keyword(s):  
Composition Range ◽  
Magnetic Hyperfine Field ◽  
Band Model ◽  
Hyperfine Fields ◽  
Ni Alloys ◽  
Dilute Alloys ◽  
Ni Alloy ◽  
Bulk Magnetization ◽  
Bcc Phase ◽  
Alloy Systems

Abstract The Ir-Fe and Ir-Ni alloy systems were studied over the whole composition range by means of the nuclear resonance absorption of the 73 keV y-rays of 193Jr and of the 14.4 keV y-rays of 57Fe. The magnetic hyperfine field at the Ir-nuclei in Ir-Ni alloys decreases approximately linearly with the Ir concentration from - 460 kOe at 4.2 K in very dilute alloys to zero at about 20 at.-% Ir. This behaviour is paralleled by the decrease of the magnetic moment per Ni atom as determined from bulk magnetization measurements. The hyperfine fields at both Ir and Fe were measured for the ferromagnetic bcc phase of the Ir-Fe system. They turned out to be virtually independent of concentration with values of about -1400 kOe and - 330 kOe, respectively. Linewidths increasing with the Ir concentration indicate a distribution of hyperfine fields. The fee phase of the Ir-Fe system has been found to be paramagnetic at 4.2 K throughout the range of its existence. The dependence of the hyperfine fields on concentration is discussed in terms of a rigid 3d-band model combined with local shielding. A discussion of the concentration dependence of the 193Ir and 57Fe isomer shifts has to take into account lattice expansion as well as band repopulation effects.

Competitive Phase Selection in Fe-Ni Alloy Droplets

1995 ◽  
Vol 398 ◽  
Author(s):  
F. Gärtner ◽  
A. F. Norman ◽  
H. Assadi ◽  
A. L. Greer
Keyword(s):  
Free Energy ◽  
Interfacial Energy ◽  
Kinetic Modelling ◽  
Primary Phase ◽  
Drop Tube ◽  
Phase Selection ◽  
Ni Alloys ◽  
Ni Alloy ◽  
Bcc Phase ◽  
Selection Of

ABSTRACTIn the solidification of Fe-Ni droplets (≤ 30 at.% Ni), the selection of different microstructures is dominated by the competition between the bcc and ccp phases. In drop-tube experiments ccp is the primary phase in some dilute (up to 7at% Ni) alloys although the bcc phase is favoured by a lower free energy and by a lower interfacial energy with the liquid. Competitive dendrite growth is a possible explanation for the formation of primary ccp. Comprehensive thermodynamic (CALPHAD) and kinetic modelling is undertaken to understand the growth competition. The origin of the observed primary phases is discussed.

A Comparative Study of the Al—Co—Pd and Al—Co—Ni Alloy Systems.

ChemInform ◽  
2004 ◽  
Vol 35 (24) ◽  
Author(s):  
M. Yurechko ◽  
B. Grushko ◽  
T. Ya. Velikanova ◽  
K. Urban
Keyword(s):  
Comparative Study ◽  
Ni Alloy ◽  
Alloy Systems

Synthesis and Magnetic Properties of Nanocrystalline Co-Ni Alloys: A Review

2012 ◽  
Vol 736 ◽  
pp. 229-240 ◽  
Author(s):  
Sudhakar Panday ◽  
P. Jeevanandam ◽  
B.S. Sunder Daniel
Keyword(s):  
Magnetic Properties ◽  
Binary Alloys ◽  
Synthesis Method ◽  
Surface Oxidation ◽  
Alloy Nanoparticles ◽  
Ni Alloys ◽  
Alloy Particles ◽  
Ni Alloy ◽  
Co Concentration ◽  
Potential Applications

This review article deals with the synthesis, characterization and magnetic properties of Co-Ni nanoalloys. The various physical and chemical methods for the synthesis of Co-Ni alloy nanoparticles are discussed. Co-Ni alloy nanoparticles with different size and shape such as spherical, rods, wires chain-like assembly are found to depend on the synthesis method and experimental condition. The structure of Co-Ni alloys is eitherfcc,hcpor mixedfccandhcpphase and found to depends on size, shape and concentration of Co in the Co-Ni alloys. Sodium hydroxide (NaOH) concentration and Co to Ni ratio influence the shape of bimetallic Co-Ni nanoparticles. Pt nucleating agents produced smaller size of Co-Ni alloy particles compared to Ru and Ag. Higher Co concentration in the Co-Ni alloys also influences the size alloy particles. The magnetic properties of Co-Ni nanoalloys depend on the size, shape and composition of the binary alloys. Surface oxidation of Co-Ni alloy nanoparticles decrease the saturation magnetization and increases with Co concentration in the alloys. The shape of Co-Ni alloy nanoparticles has an influence on coercivity. The microwave absorption properties of the Co-Ni alloys found to depend on the shape, size and composition of the binary alloys. The absorbance peaks shifts to higher frequency with decrease in size of the alloy particles. Potential applications of Co-Ni alloys in various fields are highlighted.

197Au MÖssbauer Study of Au/Fe, Au/Co and Au/Ni Magnetic Multilayers

1995 ◽  
Vol 384 ◽  
Author(s):  
Saburo Nasu ◽  
Yasuhiro Kobayashi
Keyword(s):  
Hyperfine Field ◽  
Magnetic Hyperfine Field ◽  
Ferromagnetic Layer ◽  
Magnetic Multilayers ◽  
Electron Spin Polarization ◽  
Hyperfine Fields ◽  
Mössbauer Study ◽  
Mössbauer Measurements ◽  
Local Environments ◽  
Ferromagnetic Layers

ABSTRACT197Au Mössbauer measurements have been performed for Au/Fe, Au/Co and Au/Ni magnetic multilayers. 197Au Mössbauer spectra observed from multilayers consist of at least 4 components having different magnitude of hyperfine fields and isomer shift values those depend on the local environments of the Au probe-atoms in multilayers. Rather large electron spin polarization at Au atoms has been observed in the interface with adjacent ferromagnetic layers, but nearly no magnetic hyperfine field has been observed to the interior of Au layer. It implies that the largest hyperfine field observed is not due to the conduction-electron polarization but induced by the hybridization in the interface with ferromagnetic layer.

Preparation of V-based Alloy Membranes using Chemical Transport Process

2002 ◽  
Vol 752 ◽  
Author(s):  
Tetsuya Ozaki ◽  
Yi Zhang ◽  
Masao Komaki ◽  
Chikashi Nishimura
Keyword(s):  
Substrate Temperature ◽  
Chemical Transport ◽  
Fused Silica ◽  
Hydrogen Purification ◽  
Silica Tube ◽  
Source Temperature ◽  
Ni Substrate ◽  
Ni Alloys ◽  
Ni Alloy ◽  
And Diffusion

ABSTRACTNovel preparation process of V-Ni alloys for hydrogen purification membrane using chemical transport was investigated. Vanadium, NH4Cl, and PtCl2 as evaporating source were put in one side of a fused-silica tube, and Ni substrate was put in the other side. The fused-silica tube was sealed in vacuo, and set in a furnace with temperature gradients. Evaporating source temperature was 1173–1273 K. Substrate temperature was 3–100 K higher than the evaporating source temperature. This process consists of formation of HCl from NH4Cl and PtCl2, chemical transport of vanadium under temperature gradient via chlorides in the presence of HCl, and diffusion of the transported V into the Ni substrate. EDX line profile of cross section of the substrates after the process demonstrated that V diffused into the Ni substrates. Distribution of V concentration in the substrates was dependent on the substrate temperature and the temperature difference between the substrate and the evaporating source. Heating condition was optimized to obtain homogeneous V-Ni alloy. When the substrate temperature and evaporating-source temperature were 1228 K and 1223 K, respectively, V diffused homogeneously into the Ni substrate with thickness of 20 μm, and V concentration attained in the substrate was higher than 70at%.

Modeling Internal Oxidation of Binary Ni Alloys

2011 ◽  
Vol 696 ◽  
pp. 82-87 ◽  
Author(s):  
Georgina Zimbitas ◽  
Willem G. Sloof
Keyword(s):  
Reaction Time ◽  
Numerical Model ◽  
Solubility Product ◽  
Specific Model ◽  
Alloying Element ◽  
Matlab Toolbox ◽  
Internal Oxide ◽  
Ni Alloys ◽  
Ni Alloy ◽  
Oxide Precipitate

A numerical model is presented to simulate the diffusional transport of oxygen and that of an alloying element, within a 1-D binary Ni alloy, leading to the selective oxidation of the alloying element and the formation of an internal oxide precipitate. This specific model is written in MATLAB and, with the aid of the Matlab Toolbox, is coupled to the ThermoCalc extensive database. A reaction time is introduced to overcome problems related to the difficulty of formation of the internal oxide. Two cases are considered: Al as the alloying element for which the solubility product of the oxide forming elements is small, and Mn for which it is large.

Physical Properties of Partially Crystallized Fe80B20 Amorphous Alloys

1995 ◽  
Vol 400 ◽  
Author(s):  
D. Fiorani ◽  
F. Malizia ◽  
F. Ronconi ◽  
M. Vittori Antisari
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Growth Process ◽  
Magnetic Hyperfine Field ◽  
Nucleation And Growth ◽  
Hyperfine Fields ◽  
Low Field ◽  
Transmission Electron ◽  
Mössbauer Spectrometer ◽  
Radial Structure

AbstractThe magnetic properties and hyperfine fields were investigated at low temperatures on amorphous Fe80B20 ribbons crystallized at the end of the nucleation-and-growth process without involving coarsening process. The results obtained by SQUID magnetometer and Mössbauer spectrometer show that saturation magnetization and mean magnetic hyperfine field values are greater than those in both the parent amorphous phase and in the fully crystallized structure where coarsening and grain growth processes are involved. Below 200 K irreversibility is observed in low field magnetization measurements. Transmission electron microscopy measurements reveal that spherulites of Fe3B include a radial structure made of small bcc-Fe acicular crystals about 200 nm long and 10 nm wide. In our opinion, magnetic properties and hyperfine fields are ruled by both high magnetic anisotropy of small monodomain acicular bcc-Fe crystallites and the structure of Fe atoms located at their surfaces.

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