THERMOMAGNETIC PROPERTIES OF RARE-EARTH REPLACEMENT CRITICAL MAGNETIC MATERIALS FROM DFT CALCULATION: MnBi AND MnSb

2012 ◽  
Vol 01 (04) ◽  
pp. 1250036
Author(s):  
SOO KYUNG KIM ◽  
DONGSHENG LI ◽  
MOE A. KHALEEL ◽  
KIM F. FERRIS ◽  
HAMID GARMESTANI
Keyword(s):  
Rare Earth ◽  
Elevated Temperatures ◽  
Magnetic Energy ◽  
Ferromagnetic Material ◽  
Design Rule ◽  
Energy Product ◽  
Nias Type Structure ◽  
Increasing Temperature ◽  
Thermomagnetic Properties ◽  
Nias Type

MnBi has gained much attention as a replacement for critical rare earth magnetic material not only due to its strong magnetization and coercive power, but also because of its capability to retain magnetization at elevated temperatures while most other compounds decline. To investigate the origin of this temperature dependence, we have performed a series of first principles electronic structure calculations on the thermomagnetic properties of MnBi and compared it with MnSb , another ferromagnetic material with a strong magnetic energy product, same crystal structure at room temperature and similar Curie temperature. Three structural phases were considered in this study: NiAs -type ( B81 ), MnP -type ( B31 ) and a zincblende-type ( B3 ) structures. Calculated magnetizations demonstrated structural effects on temperature dependent magnetization. For the same NiAs -type structure, MnBi has a monotonic increase in magnetization with increasing temperature while MnSb decreases. In the other two structures, magnetization in MnBi and MnSb are much less sensitive to temperature. Results from this study suggest a structural design rule for the development of new MnBi related materials.

Effect of Annealing on the Microstructure and Magnetic Properties of 2J4 Alloy

2016 ◽  
Vol 852 ◽  
pp. 84-89
Author(s):  
Chun Hong Li ◽  
Deng Ming Chen ◽  
Si Huang ◽  
Yi Long Ma ◽  
Jian Chun Sun ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Performance ◽  
Magnetic Energy ◽  
Domain Boundary ◽  
Magnetic Domain ◽  
Microstructural Characterization ◽  
Energy Product ◽  
Increasing Temperature ◽  
Precipitated Phases

The effect of annealing on the microstructural characterization and magnetic properties of 2J4 alloy has been investigated.The alloys were annealed in argon atmosphere for 0.5h at different temperatures.The results indicated that there were some precipitated phases afer annealing,which can pin domain boundary movement, thus leading to improved magnetic energy product and hysteresis properties due to enhanced coercivity and remanence. Magnetic domain morphology showed that the number of domains increased after heat treatment, the exchange energy between magnetic domains and the energy of magnetocrystalline anisotropy increased with increasing domain number,thus leading to better coercivity. With increasing temperature from 620°C to 680°C, saturation magnetization increased at first, and then decreased under the effect of increase in precipitates and decrease in strain and dislocations. The coercivity,hysteresis loss and ratio of the remanence to saturation magnetization keeped increasing due to increase of tiny and dispersed precipitates. This study can provide theoretically a reliable way for preparing 2J4 magnetic alloys with high performance.

GECOR

Alloy Digest ◽  
1972 ◽  
Vol 21 (9) ◽  
Keyword(s):  
Magnetic Material ◽  
Rare Earth ◽  
Physical Properties ◽  
Magnetic Energy ◽  
Rare Earth Metals ◽  
General Electric Company ◽  
Electric Company ◽  
Energy Product ◽  
Magnet Alloy ◽  
Permanent Magnet Alloy

Abstract GECOR is a cobalt-rare earth metals permanent magnet alloy. It has the highest magnetic energy product of any commercial magnetic material. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on machining and joining. Filing Code: Co-65. Producer or source: General Electric Company, Magnetic Materials Section.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

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.

scholarly journals Strengthening epoxy adhesives at elevated temperatures based on dynamic disulfide bonds

2020 ◽  
Vol 1 (9) ◽  
pp. 3182-3188
Author(s):  
Hsing-Ying Tsai ◽  
Yasuyuki Nakamura ◽  
Takehiro Fujita ◽  
Masanobu Naito
Keyword(s):  
Glass Transition ◽  
Disulfide Bonds ◽  
Epoxy Resins ◽  
Elevated Temperatures ◽  
Adhesive Properties ◽  
Epoxy Adhesives ◽  
Transition Points ◽  
Increasing Temperature

Epoxy resins incorporating aromatic disulfide bonds demonstrated improved adhesive properties with increasing temperature below their glass transition points.

Tensile Properties of Low Nickel Austenitic Stainless Steel at Elevated Temperatures

2012 ◽  
Vol 159 ◽  
pp. 346-350
Author(s):  
Shu Min Liu ◽  
Jian Bin Zhang
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Elevated Temperatures ◽  
Peak Stress ◽  
Temperature Curve ◽  
Delta Ferrite ◽  
Cross Sectional ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Reduction Percentage

The elevated temperature short-time tensile test with the sample of casting low nickel stainless steel was conducted on SHIMADZU AG-10 at ten temperatures 300, 500, 600, 700, 800, 950, 1000, 1050, 1100, and 1250°C, respectively. The stress-strain curves with the thermal deformation at the different temperatures, the peak stress intensity-temperature curve, and the reduction percentage of cross sectional area-temperature curve were obtained. Metallographic test samples were prepared and the morphology of deforming zone was observed by optical microscopy. The experimental results show that the tensile strength of the test samples decreases with increasing temperature. From 300 to 800°C, the work harding occurred and the tensile strength increases with increasing strain. The work softening occurred and the tensile strength decreases with increasing strain at temperatures of 800 to 1250°C. The minimum value of reduction percentage was measured at 800 °C. The austenite and delta-ferrite are the main phase in the tested samples. When the tensile temperatures are increased to 1200°C, the delta-ferrite became thinner and broke down to be spheroidized.

A Brief Overview on High Temperature Friction and Wear

2010 ◽  
Author(s):  
Mustafa Bulut Coskun ◽  
Mahmut Faruk Aksit
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Friction And Wear ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Wear Performance ◽  
Large Pressure ◽  
Higher Power ◽  
Vibratory Motion ◽  
Increasing Temperature

With the race for higher power and efficiency new gas turbines operate at ever increasing pressures and temperatures. Increased compression ratios and firing temperatures require many engine parts to survive extended service hours under large pressure loads and thermal distortions while sustaining relative vibratory motion. On the other hand, wear at elevated temperatures limits part life. Combined with rapid oxidation for most materials wear resistance reduces rapidly with increasing temperature. In order to achieve improved wear performance at elevated temperatures better understanding of combined wear and oxidation behavior of high temperature super alloys and coatings needed. In an attempt to aid designers for high temperature applications, this work provides a quick reference for the high temperature friction and wear research available in open literature. High temperature friction and wear data have been collected, grouped and summarized in tables.

Sign in / Sign up

Export Citation Format

Share Document