Susceptibility of Chromium?Based Alloys of Transition Elements

1960 ◽  
Vol 13 (2) ◽  
pp. 451 ◽  
Author(s):  
WM Lomer
Keyword(s):  
Magnetic Properties ◽  
Transition Metals ◽  
Specific Heat ◽  
Room Temperature ◽  
Spin Moment ◽  
Transition Elements ◽  
Dilute Solutions ◽  
Spin Orientation ◽  
Local Moments ◽  
The Matrix

The magnetic properties of chromium�based alloys with the transition metals are very varied. Below room temperature it is believed that chromium is antiferrcmagnetic and in this paper we investigate briefly the nature of the influence of this antiferrcmagnetic matrix on the properties of dilute solutions of atoms carrying weIl�defined local moments of their own. It is shown that various anomalies in the susceptibility-temperature relations can be rationalized in terms of a model involving small spin orientation forces arising from the antiferromagnetism. Alloying with vanadium appears to reduce the spin moment on the chromium atoms, but to introduce no localized spins itself. The temperature.independent contribution of cobalt in solution is interpreted in terms of local spins locked by the antiferromagnetism of the matrix. The :results so far obtained suggest that careful specific heat measurements in the range 0--100 OK may disclose very significant anomalies in many of. these alloys.

Can the Number of D Electrons in Transition Metals be Measured from White Lines?

1997 ◽  
Vol 3 (S2) ◽  
pp. 957-958 ◽  
Author(s):  
P. Rez
Keyword(s):  
Transition Metals ◽  
Energy Loss ◽  
Electron Energy ◽  
Transition Elements ◽  
White Line ◽  
Line Intensities ◽  
Continuum Region ◽  
The Matrix ◽  
Image Position ◽  
Electron Energy Loss

Sharp peaks at threshold are a prominent feature of the L23 electron energy loss edges of both first and second row transition elements. Their intensity decreases monotonically as the atomic number increases across the period. It would therefore seem likely that the number of d electrons at a transition metal atom site and any variation with alloying could be measured from the L23 electron energy loss spectrum. Pearson measured the white line intensities for a series of both 3d and 4d transition metals. He normalised the white line intensity to the intensity in a continuum region 50eV wide starting 50eV above threshold. When this normalised intensity was plotted against the number of d electrons assumed for each elements he obtained a monotonie but non linear variation. The energy loss spectrum is given bywhich is a product of p<,the density of d states, and the matrix elements for transitions between 2p and d states.

A New Idea for Improving Heat Fade Performance of Organic Based Friction Materials

2011 ◽  
Vol 194-196 ◽  
pp. 359-362
Author(s):  
Gui Hua Hou ◽  
Zhan Hong Wang ◽  
Yui Chi Cui
Keyword(s):  
Heat Capacity ◽  
Friction Coefficient ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Friction And Wear ◽  
Room Temperature ◽  
Friction Materials ◽  
The Matrix ◽  
High Specific Heat ◽  
Reference Samples

A new idea for improving heat fade performance of organic based friction materials was invented; the method is to dope high specific heat material to the matrix for increasing the specific heat capacity of matrix. In this paper, selecting mullite as additive, organic based friction samples doping mullite were prepared by thermoforming methods, the specific heat of samples were analyzed by TG-DSC, and its friction and wear were tested by GB/T 5764-1998 in China. The results show that doping mullite to matrix can dramatically improve the heat fade performance of organic based friction materials, the friction coefficient of samples can keep steady among 0.3-0.4 when the test temperature is from room temperature to 350°C,while the friction coefficient of the reference samples without mullite decline from 0.38 to 0.19.

scholarly journals Microstructure and Magnetic Properties of Grain Refined Pr2Co14B Melt-Spun Ribbons

2019 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
I. Nlebedim ◽  
M. Huang ◽  
K. Sun ◽  
L. Zhou ◽  
R. McCallum ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Anisotropy Field ◽  
Triple Junctions ◽  
Heat Treated ◽  
Melt Spun ◽  
The Matrix ◽  
Melt Spun Ribbons ◽  
Low Solubility ◽  
Microstructure And Magnetic Properties

The correlation between the grain refining effect of TiC on the microstructure of Pr2Co14B melt-spun ribbons and the magnetic properties is presented in this study. TiC enabled greater control of microstructure both in the as-spun and heat treated Pr2Co14B, compared with the material without TiC. As a result, coercivity of the sample with TiC was nearly twice that of the sample without TiC. In addition to Pr2Co14B, two other phases were found in the sample with TiC: one rich in Co and the other having a composition near PrCo2. TiC was found near the grain boundaries and at triple junctions. Also no Ti or C was found in the matrix phase indicating extreme low solubility of the elements when both are present with Pr2Co14B. As expected, both the samples with and without TiC have similar anisotropy field but the presence of room temperature non-ferromagnetic phases (TiC and PrCo2), caused a small decrease in magnetization of the sample with TiC although the romance of the isotropic materials were comparable.

scholarly journals Magnetic susceptibility and related properties of rare-earth crystals

1939 ◽  
Vol 170 (940) ◽  
pp. 112-129 ◽  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Specific Heat ◽  
Absorption Spectra ◽  
Room Temperature ◽  
Magnetic Susceptibilities ◽  
Temperature Range ◽  
The Mean

This paper has arisen from attempts to correlate the results of experiments on magnetic susceptibilities, specific heat and absorption spectra of rareearth crystals. No theory has yet been advanced which is capable of giving simultaneous quantitative numerical agreement on all these properties, nor indeed does it seem possible to develop such a theory. For reasons which we shall explain, it seems more likely that some of the data are wrong, or at least, that they have been wrongly interpreted. Many measurements have been made of the magnetic properties of hydrated rare-earth crystals. Accurate values of the mean molecular susceptibility, X , have been obtained over a temperature range from a few degrees absolute to room temperature, and the anisotropy of the susceptibility at room temperature has also been measured

scholarly journals The Behavior of Magnetic Properties in the Clusters of 4d Transition Metals

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1896 ◽  
Author(s):  
Habte Berry ◽  
Baolin Wang ◽  
Qinfang Zhang
Keyword(s):  
Magnetic Properties ◽  
Transition Metal ◽  
Transition Metals ◽  
Metal Clusters ◽  
Critical Size ◽  
Common Knowledge ◽  
Magnetic Behavior ◽  
Transition Metal Clusters ◽  
Transition Elements ◽  
Discrete Energy

The current focus of material science researchers is on the magnetic behavior of transition metal clusters due to its great hope for future technological applications. It is common knowledge that the 4d transition elements are not magnetic at their bulk size. However, studies indicate that their magnetic properties are strongly dependent on their cluster sizes. This study attempts to identify magnetic properties of 4d transition metal clusters. Using a tight-binding Friedel model for the density of d-electron states, we investigated the critical size for the magnetic-nonmagnetic transition of 4d transition-metal clusters. Approaching to the critical point, the density of states of the cluster near the Fermi level is higher than 1/J and the discrete energy levels form a quasi-continuous band. Where J is correlation integral. In order to determine the critical size, we considered a square shape band and fcc, bcc, icosahedral and cuboctahedral close-packed structures of the clusters. We also investigated this size dependent magnetic behavior using Heisenberg model. Taking some quantum mechanical approximations in to consideration, we determined magnetic behavior of the clusters. For practicality, we considered three clusters of transition metals (Ru, Rh and Pd) and the obtained results are in line with the results of previous studies.

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.

STRUCTURAL CHARACTERIZATION, PREPARATION AND MAGNETIC PROPERTIES OF SEVERAL ROOM-TEMPERATURE MAGNETIC OXIDES WITH THE PEROVSKITE-LIKE STRUCTURE

1977 ◽  
Vol 38 (C1) ◽  
pp. C1-95-C1-101 ◽  
Author(s):  
B. BOCHU ◽  
M. N. DESCHIZEAUX ◽  
J. C. JOUBERT ◽  
J. CHENAVAS ◽  
A. COLLOMB ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Structural Characterization ◽  
Room Temperature ◽  
Magnetic Oxides
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