The spontaneous magnetization of cobalt

1951 ◽  
Vol 207 (1091) ◽  
pp. 427-446 ◽  
Keyword(s):  
Heat Treatment ◽  
Curie Temperature ◽  
Single Crystal ◽  
Transformation Temperature ◽  
Equations Of State ◽  
Spontaneous Magnetization ◽  
Hexagonal Structure ◽  
Slow Cooling ◽  
Temperature Range ◽  
The Face

The paper describes how measurements of the spontaneous magnetization of pure specimens of single-crystal close-packed hexagonal and polycrystalline face-centred cubic cobalt have been made over the temperature range -183 to 1121° C. A single crystal of cobalt possessing a close-packed hexagonal structure was prepared by the process of slow cooling of the melt. Owing to the presence of a phase change in cobalt occurring c . 400° C when the metal changes from a close-packed hexagonal structure below 400° C to a face-centred cubic structure above 400° C, it was necessary to determine two critical rates of cooling to prepare a crystal. Magnetic test specimens of single-crystal cobalt, cut so that they were capable of being magnetized along the easy axis of magnetization (the hexagonal axis), and of polycrystalline cobalt, of approximate dimensions 4 x 2 x 2 mm., were studied using the magnetic balance devised by Sucksmith (1939). The spontaneous magnetization of the hexagonal form was accurately measured from — 183 to 431° C, this latter temperature being determined as the upper transformation temperature of the cobalt. Complete tables of these measurements are given. By extrapolation the value 162.5 5 was determined for the spontaneous magnetization of hexagonal cobalt at absolute zero of temperature. Measurements on the polycrystalline face-centred cubic material were made from 394° C (this temperature being determined as the lower transformation temperature) to the Curie temperature, determined by extrapolation to be 1121° C. The face-centred cubic material possessed greater magnetization than the hexagonal, and in the temperature range 431 to 950° C it was found to be dependent upon the heat treatment the specimen had received; the significant factor in this heat treatment being the speed with which the specimen was allowed to cool through the lower transformation temperature. The Curie temperature was not affected by this heat treatment. To determine the spontaneous magnetization at very high temperatures where no saturation was observed the extrapolation technique devised by Weiss & Forrer (1926) was used. This procedure is described. When reduced values of magnetization and temperature were calculated it was found that the hexagonal and face-centred cubic materials obeyed different reduced equations of state although excellent agreement was obtained when the reduced values for face-centred cubic cobalt were compared with similar values for nickel. These results given in detailed tabulated form show that the reduced magnetic equation of state is structure dependent.

Dielectric, piezoelectric, and pyroelectric studies of LiTaO3-derived ceramics sintered at 900°C following the addition of (LiF + MgF2)

1988 ◽  
Vol 3 (1) ◽  
pp. 112-115 ◽  
Author(s):  
Zuo-Guang Ye ◽  
R. Von Der Mühll ◽  
J. Ravez ◽  
P. Hagenmuller
Keyword(s):  
Heat Treatment ◽  
Curie Temperature ◽  
Single Crystal ◽  
Partial Substitution ◽  
Partial Hydrolysis ◽  
Hydrolysis Of

High-densified LiTaO3-type ceramics have been obtained by sintering at 900°C after the addition of small amounts of a LiF + MgF2 mixture. Partial hydrolysis of MgF2 and volatilization of either LiF, LiOH, or Li2O due to hydrolysis and partial substitution of F-ions by (OH−) occur during heat treatment. The ferroelectric Curie temperature Tc increases with the amount of additive. The ceramics have been polarized by heating to Tc and cooling down under a dc field. The piezoelectric and pyroelectric coefficients of such ceramics are approximately 30% and 20% of the corresponding values for a LiTaO3 single crystal.

Magnetic Study on Y2M3Co9P7 (M: Transition Metals) with Cation-Ordered Zr2Fe12P7-Type Structure

2019 ◽  
Vol 289 ◽  
pp. 164-169
Author(s):  
Yusuke Kato ◽  
Hiroto Ohta ◽  
Hiroko Aruga Katori
Keyword(s):  
Transition Metals ◽  
Curie Temperature ◽  
Spontaneous Magnetization ◽  
Magnetic Moments ◽  
Hexagonal Structure ◽  
Type Structure ◽  
Magnetic Study ◽  
Pauli Paramagnetism ◽  
Fe And Mn ◽  
The Stability

We successfully synthesized polycrystalline samples of Y2M3Co9P7 (M = Cr, Mn, Fe, Co, Mo, and Ru), which has the Zr2Fe12P7-type hexagonal structure with M and Co selectively occupy the pyramidal site and three tetrahedral ones, respectively. For the case of M = Co, or Y2Co12P7, the itinerant electronic ferromagnetism was observed below the Curie temperature TC = 153 K. For M = Cr, Mn, Fe, and Ru, the ferromagnetism was also observed below TC = 167 K, 229 K, 233 K and 18 K, respectively, whereas for M = Mo, an exchange-enhanced Pauli paramagnetism tool the place of the ferromagnetism. Among compounds with M being 3d transition metals, TC and spontaneous magnetization took the maximum around M = Fe and Mn. This tendency was also seen in the cases of M being 4d transition metals, i.e., M = Ru and Mo. Our result indicates that magnetic moments at the pyramidal site have rather localized nature and largely affect the stability of the ferromagnetism of Y2M3Co9P7 although the ferromagnetism is considered to be mainly derived from three Co sites.

Electro-caloric effect in a BCZT single crystal

CrystEngComm ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 1597-1602 ◽  
Author(s):  
Donglin Liu ◽  
Qiang Li ◽  
Qingfeng Yan
Keyword(s):  
Curie Temperature ◽  
Single Crystal ◽  
Wide Temperature Range ◽  
Temperature Range ◽  
Caloric Effect

The electro-caloric effect of the [001]-oriented (Ba,Ca)(Zr,Ti)O3 (BCZT) single crystal was investigated in a wide temperature range from −100 °C to Curie temperature (122 °C).

EFFECTS OF Ru AND Cr ON γ/γ' MICROSTRUCTURAL EVOLUTION OF Ni--BASED SINGLE CRYSTAL SUPERALLOYS DURING HEAT TREATMENT

2010 ◽  
Vol 46 (8) ◽  
pp. 897-906 ◽  
Author(s):  
Jingyang CHEN ◽  
Bin ZHAO ◽  
Qiang FENG ◽  
Lamei CAO ◽  
Zuqing SUN
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Microstructural Evolution

scholarly journals Creep Damage Repair of a Nickel-Based Single Crystal Superalloy Based on Heat Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 623
Author(s):  
Xiaoyan Wang ◽  
Meng Li ◽  
Yuansheng Wang ◽  
Chengjiang Zhang ◽  
Zhixun Wen
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Creep Damage ◽  
Primary Creep ◽  
Single Crystal Superalloy ◽  
Secondary Creep ◽  
Creep Life ◽  
Phase Coarsening ◽  
Damage Repair ◽  
Creep Time

Taking nickel-based single crystal superalloy DD6 as the research object, different degrees of creep damage were prefabricated by creep interruption tests, and then the creep damage was repaired by the restoration heat treatment system of solid solution heat treatment and two-stage aging heat treatment. The results show that with the creep time increasing, the alloy underwent microstructure evolution including γ′ phase coarsening, N-type rafting and de-rafting. After the restoration heat treatment, the coarse rafted γ′ phase of creep damaged specimens dissolved, precipitated, grew up, and became cubic again. Except for the specimens with creep interruption of 100 h, the γ′ phase can basically achieve the same arrangement as the γ′ phase of the original sample. The comparison of the secondary creep test shows that the steady-state creep stage of the test piece after the restoration heat treatment is relatively increased, and the total creep life can reach the same level as the primary creep life. The high temperature creep properties of the tested alloy are basically recovered, and the restoration heat treatment effect is good.

Creep Behavior of a 4.5% Re Nickel-Base Single Crystal Superalloy at High Temperature

2015 ◽  
Vol 750 ◽  
pp. 139-144 ◽  
Author(s):  
De Long Shu ◽  
Su Gui Tian ◽  
Xin Ding ◽  
Jing Wu ◽  
Qiu Yang Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Single Crystal ◽  
Deformation Mechanism ◽  
Creep Property ◽  
Single Crystal Superalloy ◽  
Micro Cracks ◽  
Initiation And Propagation ◽  
Temperature Ranges ◽  
Nickel Base

By means of heat treatment and creep property measurement, an investigation has made into the creep behaviors of a containing 4.5% Re nickel-base single crystal superalloy at high temperature. Results show that the elements W, Mo and Re are enriched in the dendrite arm regions, the elements Al, Ta, Cr and Co are enriched in the inter-dendrite region, and the segregation extent of the elements may be obviously reduced by means of heat treatment at high temperature. In the temperature ranges of 1070--1100 °C, the 4.5% Re single crystal nickel-based superallloy displays a better creep resistance and longer creep life. The deformation mechanism of the alloy during steady state creep is dislocations slipping in the γ matrix and climbing over the rafted γ′ phase. In the later stage of creep, the deformation mechanism of alloy is dislocations slipping in the γ matrix, and shearing into the rafted γ′ phase, which may promote the initiation and propagation of the micro-cracks at the interfaces of γ/γ′ phases up to the occurrence of creep fracture.

The effect of Al/Si disorder on the bulk moduli of plagioclase feldspars

2010 ◽  
Vol 74 (6) ◽  
pp. 943-950 ◽  
Author(s):  
L. M. Sochalski-Kolbus ◽  
R. J. Angel ◽  
F. Nestola
Keyword(s):  
Bulk Modulus ◽  
Single Crystal ◽  
Equations Of State ◽  
X Ray Diffraction ◽  
Volume Increase ◽  
X Ray ◽  
Density Decrease ◽  
The Relationship

AbstractThe volumes of a disordered An20 (Qod = 0.15), a disordered An78 (Qod = 0.55) and an ordered An78 (Qod = 0.81) were determined up to 9.569(10) GPa, 8.693(5) GPa and 9.765(10) GPa, respectively, using single-crystal X-ray diffraction. The volume variations with pressure for these samples are described with 4th-order Birch Murnaghan equations of state with V0 = 669.88(7) Å3, K0 = 59.7(7) GPa. K′ = 5.7(5), K″ = −0.8(2) GPa−1 for disordered An20, V0 = 1340.48(10) Å3, K0 = 77.6(5) GPa, K0′ = 4.0(3), K″ = -0.59(9) GPa−1 for disordered An78 and V0 = 1339.62(6) A3, K0 = 77.4(6) GPa, K′ = 4.2(4), and K″ = −0.7(1) GPa−1 for ordered An78. Along with data from previous studies (An0 ordered, An0 disordered and An2o ordered), the volumes for the disordered samples were found to be up to ∼0.3% larger than the ordered samples of the same composition. The disordered samples are softer than the ordered samples of the same composition by 4(1)% for An0, 2.5(9)% for An20 and essentially zero for An78. The relationship between volume increase, density decrease, and decreasing bulk modulus with increasing disorder is in accordance with Birch's Law.

Exoelectron emission from unexcited metallic glasses Fe78B13Si9 during heat treatment

1992 ◽  
Vol 7 (6) ◽  
pp. 1396-1399 ◽  
Author(s):  
Yoshihisa Watanabe ◽  
Tadayoshi Kubozoe ◽  
Yoshikazu Nakamura
Keyword(s):  
Heat Treatment ◽  
Metallic Glasses ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Exoelectron Emission ◽  
Radiation Chemical ◽  
Temperature Range ◽  
High Vacuum Condition ◽  
Before And After ◽  
Ultra High Vacuum Condition

Exoelectron emission from the surface of unexcited metallic glasses Fe78B13Si9 during heat treatment has been studied under ultra high vacuum condition. In the first heating cycle, exoelectrons are emitted from the as-cast ribbon in the temperature range from approximately 423 K to 773 K (150 °C to 500 °C), although the surface of the specimen is not excited by ionizing radiation, chemical processes, or mechanical treatments prior to measurements. In the second and subsequent heating cycles, however, there is no anomalous emission observed in the same temperature range. In order to elucidate the mechanism of emission, the surface of the specimen is observed by the atomic force microscope (AFM) before and after measurements. In the AFM image, many crystallites in the amorphous matrix can be found in the surface of the heated specimen. These experimental results show that exoelectrons are emitted in the same temperature range as the early stages of crystallization on the surface of metallic glasses. We hypothesize that the two effects are correlated.

Technique and results of experimental determination of the compressibility factor of the natural gas

2021 ◽  
pp. 35-40
Author(s):  
Denis Y. Kutovoy ◽  
Igor A. Yatsenko ◽  
Vladimir B. Yavkin ◽  
Aydar N. Mukhametov ◽  
Petr V. Lovtsov ◽  
...  
Keyword(s):  
Natural Gas ◽  
Equations Of State ◽  
Compressibility Factor ◽  
High Accuracy ◽  
State Equations ◽  
Actual Problem ◽  
Temperature Range ◽  
Relative Value ◽  
Compressibility Coefficient

The actual problem of the possibility of using the equations of state for the gas phase of natural gas at temperatures below 250 K is considered. To solve it, the compressibility coefficients of natural gas obtained experimentally with high accuracy are required. The technique was developed and experimental study was carried out of compressibility factor aiming expanding temperature range of the state equations GERG-2004 and AGA8-DC92. The proposed technique is based on the fact that to assess the applicability of the equation of state, it is sufficient to obtain the relative value of the compressibility coefficient and not to determine its absolute value. The technique does not require complex equipment and provides high accuracy. The technique was tested on nitrogen, argon, air and methane. Uncertainty of determination of the compressibility factor is not greater than 0.1 %. For two different compositions of natural gas, obtained experimental data were demonstrated that the equations of state GERG-2004 and AGA8-92DC provide uncertainty of the calculation of the compressibility coefficient within 0.1 % in the temperature range from 220 K to 250 K and pressure below 5 MPa.

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