scholarly journals Room-temperature magnetoresistance of nanocrystalline Ni metal with various grain sizes

2020 ◽  
Vol 135 (1) ◽  
Author(s):  
V. A. Isnaini ◽  
T. Kolonits ◽  
Zs. Czigány ◽  
J. Gubicza ◽  
S. Zsurzsa ◽  
...  
Keyword(s):  
Room Temperature ◽  
Coarse Grained ◽  
Zero Field ◽  
Electronic Density ◽  
Grain Sizes ◽  
The Matrix ◽  
Cold Rolling And Annealing ◽  
Resistivity Anisotropy ◽  
First Time ◽  
Matrix Resistivity

AbstractThe room-temperature magnetoresistance (MR) characteristics of nanocrystalline (nc) Ni metal with various grain sizes (between 30 and 100 nm) are investigated in this work for the first time. The nc-Ni foils were produced by electrodeposition and the results are compared with data measured on coarse-grained (bulk) pure Ni metal samples prepared by cold-rolling and annealing. The MR(H) curves measured in magnetic fields up to H = 9 kOe are analyzed in detail to determine the anisotropic magnetoresistance (AMR) ratio. The magnitude of the AMR ratio was found to be around 2.5% for bulk Ni and in the range from about 2 to 2.5% for the nc-Ni samples, the latter data not exhibiting a systematic dependence on the grain size. On the other hand, the field-induced resistivity anisotropy splitting ∆ρAMR in the magnetically saturated state of the nc-Ni series was found to be proportional to the zero-field resistivity of the same samples with different grain sizes. The slope of this proportionality relation provided an AMR ratio of 2.4% for all nc-Ni samples, matching well the value for the bulk Ni samples. Thus, the AMR ratio for polycrystalline Ni metal seems to be fairly independent of the microstructural features. This also means that the AMR ratio is an inherent characteristic of the Ni metal matrix and it remains the same even if the matrix resistivity changes (e.g., by introducing grain boundaries) without noticeably modifying the electronic density of states at least in the vicinity of the Fermi level.

scholarly journals Synthesis, Characterization and Mechanical Properties of Nanocrystalline NiAl

1996 ◽  
Vol 457 ◽  
Author(s):  
M. S. Choudry ◽  
J. A. Eastman ◽  
R. J. DiMelfi ◽  
M. Dollar
Keyword(s):  
Room Temperature ◽  
Dark Field ◽  
Inert Gas ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Grain Sizes ◽  
Room Temperature Ductility ◽  
Cast Alloys ◽  
Bend Tests

ABSTRACTNanocrystalline NiAl has been produced from pre-cast alloys using an electron beam inert gas condensation system. In-situ compaction was carried out at 100 to 300°C under vacuum conditions. Energy dispersive spectroscopy was used to determine chemical composition and homogeneity. Average grain sizes in the range of 4 to 10 nm were found from TEM dark field analyses. A compression-cage fixture was designed to perform disk bend tests. These tests revealed substantial room temperature ductility in nanocrystalline NiAl, while coarse grained NiAl showed no measurable room temperature ductility.

scholarly journals The Effect of Tanreqing Injection on the Pharmacokinetics of Sirolimus in Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Feng Zhang ◽  
Liang Sun ◽  
Jianxiu Zhai ◽  
Tianyi Xia ◽  
Wei Jiang ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Matrix Effects ◽  
Thaw Cycle ◽  
Relative Standard ◽  
The Matrix ◽  
Freeze Thaw Cycle ◽  
Liquid Chromatography Tandem Mass ◽  
The Stability ◽  
First Time

To evaluate the effect of Tanreqing injection on the pharmacokinetics of sirolimus in rats, a high performance liquid chromatography tandem mass spectrometry method was developed for sirolimus assay in whole blood. Calibration curve of sirolimus was acquired over a concentration ranging from 2.5 to 100 ng/mL with r2= 0.9955. The matrix effects and extraction recoveries of sirolimus ranged from 144% to 152% and from 80% to 96%, respectively. The inter- and intraday relative standard deviations were both <10%. The stability investigation showed that the blood samples were stable for 30-day-storage at -20°C, for 8 h storage at room temperature, for 24 h storage in the auto-sampler at 4°C, and for three freeze-thaw cycle process. The pharmacokinetic results demonstrated that the Cmax, AUC, and AUMC of sirolimus in rats (7.5 mg/kg, i.g.) were increased after beincoadministration with Tanreqing Injection at 2.5, 5.0, and 7.5 mL/kg (i.v.), respectively, or at 5 min, 2 h, and 4 h (5.0 mL/kg, i.v.) after SRL dosing, respectively. For the first time, the results proved the herb-drug interaction between Tanreqing Injection and sirolimus and accordingly suggested avoiding concurrent reception of those two drugs for patients.

Combined In Situ Neutron Diffraction and Acoustic Emission of Twin Nucleation & Twin Growth in Extruded ZM20 Mg Alloy

2010 ◽  
Vol 652 ◽  
pp. 149-154 ◽  
Author(s):  
Ondrej Muránsky ◽  
Matthew R. Barnett ◽  
David G. Carr ◽  
Sven C. Vogel ◽  
E.C. Oliver
Keyword(s):  
Acoustic Emission ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Coarse Grained ◽  
Fine Grained ◽  
Grain Sizes ◽  
Twin Nucleation ◽  
Twin Growth ◽  
In Situ Neutron Diffraction

In the present work in situ neutron diffraction and acoustic emission were used concurrently to study deformation twinning in two ZM20 Mg alloys with significantly different grain sizes at room temperature. The combination of these techniques allows differentionation between the twin nucleation and the twin growth mechanisms. It is shown, that yielding and immediate post-yielding plasticity in compression is governed primarily by twin nucleation, whereas the plasticity at higher strains is governed by twin growth. The current results further suggest that yielding by twinning happens in a slightly different manner in the fine-grained as compared to the coarse-grained alloy.

scholarly journals The Effect of Hydrogen on Martensite Transformations and the State of Hydrogen Atoms in Binary TiNi-Based Alloy with Different Grain Sizes

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3956 ◽  
Author(s):  
Baturin ◽  
Lotkov ◽  
Grishkov ◽  
Rodionov ◽  
Kabdylkakov ◽  
...  
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Room Temperature ◽  
Hydrogen Diffusion ◽  
Thermal Desorption Spectroscopy ◽  
Coarse Grained ◽  
Hydrogen Atoms ◽  
Grain Sizes ◽  
Martensite Transformations ◽  
Kinetics Of

The analysis presented here shows that in B2-phase of Ti49.1Ni50.9 (at%) alloy, hydrogenation with further aging at room temperature decreases the temperatures of martensite transformations and then causes their suppression, due to hydrogen diffusion from the surface layer of specimens deep into its bulk. When hydrogen is charged, it first suppresses the transformations B2↔B19′ and R↔B19′ in the surface layer, and when its distribution over the volume becomes uniform, such transformations are suppressed throughout the material. The kinetics of hydrogen redistribution is determined by the hydrogen diffusion coefficient DH, which depends on the grain size. In nanocrystalline Ti49.1Ni50.9 (at%) specimens, DH is three times greater than its value in coarse-grained ones, which is likely due to the larger free volume and larger contribution of hydrogen diffusion along grain boundaries in the nanocrystalline material. According to thermal desorption spectroscopy, two states of hydrogen atoms with low and high activation energies of desorption exist in freshly hydrogenated Ti49.1Ni50.9 (at%) alloy irrespective of the grain size. On aging at room temperature, the low-energy states disappear entirely. Estimates by the Kissinger method are presented for the binding energy of hydrogen in the two states, and the nature of these states in binary hydrogenated TiNi-based alloys is discussed.

Tribological Study of Ti3SiC2 and Its Derivatives

2005 ◽  
Author(s):  
Surojit Gupta ◽  
Z. M. Sun ◽  
M. W. Barsoum ◽  
T. Palanisamy ◽  
E. Passman
Keyword(s):  
Wear Resistance ◽  
Wear Rate ◽  
Friction And Wear ◽  
Room Temperature ◽  
Basic Mechanism ◽  
Coarse Grained ◽  
Wear Properties ◽  
Wear Resistant ◽  
Tribological Study ◽  
The Matrix

In this paper, we report on the tribological and wear properties of Ti3SiC2 and its derivatives. Coarse-grained Ti3SiC2 was not wear resistant at room temperature. Preoxidation of the material at 700 °C for 5 h also failed to ameliorate the situation at room temperature. Addition of 20 vol.% Cu in the matrix improved the wear rate for up to 1500 m; beyond that distance the friction and wear increased. Ti3SiC2 tested at 500 °C showed improved wear resistance most probably due to the formation of oxide tribofilms. More work is being done to understand the basic mechanism behind this behavior.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

The butterfly martensite nucleation in an iron and nickel alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 906-907
Author(s):  
Q.Z. Chen ◽  
X.F. Wu ◽  
T. Ko
Keyword(s):  
Nickel Alloy ◽  
Ethyl Alcohol ◽  
Dislocation Structure ◽  
Martensite Transformation ◽  
Room Temperature ◽  
The Matrix

Some butterfly martensite nuclei were observed in an Fe-27.6Ni-0.89V-0.05C alloy. The alloy was austenitized at 1200°C for 1 hour. Some samples were aged at 850° C for 40 minutes and quenched in 10% brine at room temperature. All the samples were cooled in ethyl alcohol for martensite transformation.A nucleus in an unaged specimen is shown in Fig.1. The nucleus has certain contrast different from the matrix and is shaped like one wing of a butter fly martensite. The SADP of the circled region is measured to be: da=dh, and approximate to dγ(111) and dm(110) with ∠AOB = 55° . It is similar to [011]f.c.c and b patterns in the anglez ∠AOB and the ratio ra/rb, respectively. The SADP shows that the structure of the nucleus is between f.c.c and b.c.c. The dislocation structure within the nucleus is shown in Fig.2. Their Burgers vectors and line directions are also given in it. There are many long dislocations near it without dislocations piled up as shown in Fig.3.Long dislocations are closed at one end as an envelope.

Room-temperature white and color-tunable afterglow by manipulating multi-mode triplet emissions

2021 ◽  
Vol 9 (9) ◽  
pp. 3257-3263
Author(s):  
Jianwei Liu ◽  
Zhimin Ma ◽  
Zewei Li ◽  
Yan Liu ◽  
Xiaohua Fu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Component ◽  
Color Tunable ◽  
First Time ◽  
Multi Mode

Two isomers pDCzPyCN and oDCzPyCN are designed and synthesized. Amazingly, oDCzPyCN manifest white afterglow at room temperature. This is the first time that single-component white afterglow has finally been realized.

Dioxygen splitting at room temperature over distant binuclear transition metal centers in zeolites for direct oxidation of methane to methanol

2021 ◽  
Author(s):  
Kinga Mlekodaj ◽  
Mariia Lemishka ◽  
Stepan Sklenak ◽  
Jiri Dedecek ◽  
Edyta Tabor
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Direct Oxidation ◽  
Metal Centers ◽  
Oxidation Of Methane ◽  
First Time

Here we demonstrate for the first time the splitting of dioxygen at RT over distant binuclear transition metal (M = Ni, Mn, and Co) centers stabilized in ferrierite zeolite. Cleaved...

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