Elevated Temperature Properties of Sintered Magnets of (Nd,Dy)-Fe-B Modified with Cobalt and Aluminum

1987 ◽  
Vol 96 ◽  
Author(s):  
Y. Xiao ◽  
H. F. Mildrum ◽  
K. J. Strnat ◽  
A. E. Ray
Keyword(s):  
Elevated Temperature ◽  
Side Effects ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Open Circuit ◽  
Sintered Magnets ◽  
Temperature Coefficients ◽  
Energy Product ◽  
Intrinsic Coercivity ◽  
Curie Temperatures

ABSTRACTThe effect of small aluminum additions on the temperature dependence of remanence and intrinsic coercivity in Co- and Dy-containing Nd-Fe-B was studied. Sintered magnets were prepared and demagnetization curves measured at temperatures between −50 to +200°C. Curie temperatures and irreversible flux losses in open circuit were determined. Al increases the coercivity while decreasing remanence, energy product and Curie temperature. Other unfavorable side effects are the increase in temperature coefficients of Br and, especially, MHc. Substitution of Al is not beneficial for magnets used at elevated temperature.

NdFeB Magnets with Improved Temperature Characteristics

1987 ◽  
Vol 96 ◽  
Author(s):  
B. M. Ma
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Temperature Coefficients ◽  
System A ◽  
Rate Of Increase ◽  
Intrinsic Coercivity ◽  
Molybdenum Addition

ABSTRACTThe temperature dependence of magnetic properties for NdFeCoB alloys were investigated. It is well known that dysprosium substitution for neodymium increases the intrinsic coercivity. Aluminum also improves the intrinsic coercivity, Hci, at room temperature but impairs the Curie temperature and the intrinsic coercivity at elevated temperatures. The rate of increase of the Hci with increasing dysprosium in the NdFeCoB system is less than when dysprosium is added to the NdFeB system. A combination of aluminum and dysprosium is more effective than aluminum alone in raising Hci. Molybdenum addition into the NdDyFeCoB alloy was found to reduce the temperature coefficients of Br and Hci. Temperature coefficients of Br and Hci obtained on a Nd10Dy5Fe67Co10Mo1Al1B6 alloy are -0.07 %/°C and -0.4 %/°C respectively.

RAECO-15

Alloy Digest ◽  
1972 ◽  
Vol 21 (12) ◽  
Keyword(s):  
Curie Temperature ◽  
Coercive Force ◽  
Physical Properties ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Energy Product ◽  
Magnet Alloy

Abstract RAECO-15 is a magnet alloy of samarium and cobalt which offers 15-million energy product, an extremely high intrinsic coercive force (Hci = 15,000 Oe), and a Curie Temperature of 750 C. It is especially attractive for use in severe demagnetizing environments at elevated temperatures. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, machining, and joining. Filing Code: Co-67. Producer or source: Raytheon Microwave and Power Tube Division.

MICROSTRUCTURE AND TEMPERATURE STABILITY OF SINTERED Nd-Dy-Fe-Co-Mo-Al-B MAGNETS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 721-724
Author(s):  
W. RODEWALD ◽  
P. SCHREY ◽  
B. WALL
Keyword(s):  
Solid Solution ◽  
Surface Treatment ◽  
Corrosion Behaviour ◽  
Temperature Stability ◽  
Partial Replacement ◽  
Compound A ◽  
Corrosion Tests ◽  
Sintered Magnets ◽  
Load Line ◽  
Intrinsic Coercivity

Simultaneous additions of Co and Mo or V, respectively, to Nd-Dy-Fe-Al-B alloys improve the temperature stability of sintered magnets. The intrinsic coercivity at 150 ºC amounts to 9 kA/cm for magnets with a Dy-content of 3 at.%. Hence magnets with a load line, B/μoH=−2, may be operated at temperatures up to 200 ºC. The additions of Mo or of V result in the precipitation of a tetragonal Mo2FeB2 compound, a=0.58 nm, c=0.32 nm, or of a tetragonal V3–xFexB2 compound, x=0.2...1.2, within the (Nd, Dy)2(Fe, Co, A1)14B grains. The dimensions of the precipitates range from 10 to 600 nm. Besides Mo2FeB2- or V3–xFex+B2-grains, respectively, with dimensions up to 10 μm were observed within the Nd-rich constituents. The intrinsic coercivity, however, is determined by nucleation of reversed domains. The addition of Co results in a partial replacement of the Nd-Fe solid solution by the Nd3Co compound. Corrosion tests revealed, that the corrosion behaviour is not improved significantly and depends much more on the surface treatment.

Temperature dependence of chlorine-35 N.Q.R. in 2,6-Dichlorophenol

1978 ◽  
Vol 31 (4) ◽  
pp. 791 ◽  
Author(s):  
R Chandramani ◽  
SP Basavaraju ◽  
N Devaraj
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Brown's Method

Chlorine n.q.r, in 2,6-dichlorophenol has been investigated at temperatures from 77 K to room temperature. Two resonance lines due to chemically inequivalent sites have been observed throughout this temperature range. Torsional frequencies of the molecule have been calculated at temperatures from 77 to 300 K according to Bayer's theory and Brown's method. Also the temperature coefficients of the torsional frequencies have been calculated.

NQR and Crystal Structure of 4,5-Dichloroimidazole, C3H2N2Cl2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 177-181 ◽  
Author(s):  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Unit Cell ◽  
Space Group ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Group D

AbstractThe two line 35Cl NQR spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR spectrum are discussed.

scholarly journals The effects of additive on microstructure and electrical properties of batio3 ceramics

2004 ◽  
Vol 1 (3) ◽  
pp. 89-98 ◽  
Author(s):  
Vesna Paunovic ◽  
Ljiljana Zivkovic ◽  
Ljubomir Vracar ◽  
Vojislav Mitic ◽  
Miroslav Miljkovic
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Room Temperature ◽  
Low Frequency ◽  
Dissipation Factor ◽  
The Other ◽  
Uniform Microstructure ◽  
Average Grain Size ◽  
Solid State Sintering ◽  
Curie Temperatures

In this paper comparative investigations of microstructure and dielectric properties of BaTiO3 ceramics doped with 1.0 wt% of Nb2O5, MnCO3 and CaZrO3 have been done. BaTiO3 samples were prepared using conventional method of solid state sintering at 13000C for two hours. Two distinguish micro structural regions can be observed in sample doped with Nb2O5. The first one, with a very small grained microstructure and the other one, with a rod like grains. In MnCO3 and CaZrO3 doped ceramics the uniform microstructure is formed with average grain size about 0.5- 2?m and 3-5?m respectively. The highest value of dielectric permittivity at room temperature and the greatest change of permittivity in function of temperature were observed in MnCO3/BaTiO3. In all investigated samples dielectric constant after initially large value at low frequency attains a constant value at f = 6kHz. A dissipation factor is independent of frequency greater than 10 kHz and, depending of systems, lies in the range from 0.035 to 0.25. At temperatures above Curie temperatures, the permittivity of all investigated samples follows a Curie- Weiss law. A slight shift of Curie temperature to the lower temperatures, in respect of Curie temperature for undoped BaTiO3, was observed in all investigated samples.

scholarly journals Temperature dependence of phonons in Pd3Fe through the Curie temperature

2018 ◽  
Vol 98 (2) ◽  
Author(s):  
F. C. Yang ◽  
O. Hellman ◽  
M. S. Lucas ◽  
H. L. Smith ◽  
C. N. Saunders ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Temperature Dependence

A class of Pb-free double perovskite halide semiconductors with intrinsic ferromagnetism, large spin splitting and high Curie temperature

2018 ◽  
Vol 5 (5) ◽  
pp. 961-968 ◽  
Author(s):  
Bo Cai ◽  
Xi Chen ◽  
Meiqiu Xie ◽  
Shengli Zhang ◽  
Xuhai Liu ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Double Perovskite ◽  
Spin Splitting ◽  
Ferromagnetic Semiconductors ◽  
High Curie Temperature ◽  
Intrinsic Ferromagnetism ◽  
Curie Temperatures ◽  
Large Spin

We introduce perovskite halides into spintronics, and these materials are ferromagnetic semiconductors with large spin splitting and high Curie temperatures.

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