A.R. Kiani-Rashid
材料科学技术（英文）
The purpose of this study was to determine the influence of heat treatment cycle on graphite phase formation on CK 45 steel. The presence of well distributed graphite in the matrix is responsible for the good mechanical and thermal properties of this kind of alloy. Such properties include excellent wear resistance, higher resistance to thermal shock, and higher resistance to oxidation at high temperature. A number of specimens were made up of appropriate design to provide the experimental materials. The transformation phase to a free carbon microstructure during graphitization under different conditions was then examined for the most successful experimental steels. Austenitising temperature of 920°C and the following isothermal heat treatment of 750°C at different holding times were used. Microstructures were examined by OM (optical microscopy) and SEM (scanning electron microscopy). Furthermore, it was found that isothermal transformation at 750°C for different soaking times produced a typical microstructure. Also, the amount of graphite increased with increasing isothermal heat treatment time. Heat treatment leading to supersaturation of iron with carbon was described and some of the consequences of the supersaturation were presented. Finally, the formation of the thermodynamically stable state of the graphite taken from the supersaturated solid solution was discussed.
关键词:
Graphitization
Communications in Theoretical Physics
The unified theoretical calculation of thermal shifts (TS) of R-1 and R-2 lines and thermal broadenings (TB) of R, R' and B lines for ruby was carried out for the first time. The calculated results are in very good agreement with a great number of experimental data. Especially by using quantum theory and taking into account all the admixtures of wavefunctions within d(3) electronic configuration, all the Gamma M in electron-phonon interaction (EPI), the electronic energy spectrum and lattice-vibration Spectrum, the very important contributions to TS and TB from single-phonon direct process were theoretically calculated in detail. The microscopic essentials of various contributions are revealed, and the mistakes in previous work are remedied.
关键词:
diamond anvil cell;pressure measurement;spectroscopy;temperatures
Communications in Theoretical Physics
On the basis of the unified calculation of the thermal shifts of R-1 line, R-2 line and ground-state-splitting as well as the thermal broadenings of R, R' and B line-groups for ruby, by taking into account all the levels and admixtures of wavefunctions within d(3) electronic configuration and all the GammaM in electron-phonon interaction, the transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings, of R, R' and B line-groups have successfully been interpreted in terms of the direct and Raman processes of acoustic phonons. The theoretically predicted transition probabilities are in good agreement with the experimental ones.
关键词:
crystal fields;electron-phonon interaction;thermal broadening;transition probability;direct and Raman processes;shifts
Transactions of Nonferrous Metals Society of China
Phase equilibria of the R-Fe-Co pseudoternary system with R less than or equal to 33.3% ( mole fraction, R = Sm0.5Dy0.5) were determined in an isothermal section at 1073 K and a vertical section of RFe2-RCo2 by using OM, X-ray diffractometer, EP-MA DTA techniques. There are seven intermetallic phases: (Sm, Dy) (Fe, Co)(2), (Sm, Dy) (Fe, Co)(3), (Sm, Dy)(6) (Fe, Co)(23), (Sm, Dy)(2) (Fe, Co)(7), (Sm, Dy) (Fe, Co)(5), Th2Ni17-type and Th2Zn17-type (Sm, Dy)(2)(Fe, Co)(17). The (Sm, Dy)(6)(Fe, Co)(23) phase dissolves 36% Co(mole fraction) at 1073 K. However, the (Sm, Dy)(2)(Fe, Co)(7) phase in R-2(Fe1-xCox)(7) alloys dissolves about 19% Fe(mole fraction) at 1073 K.
关键词:
rare earth-iron-cobalt;phase diagram;structure;compounds;sm-co;magnetic-properties;binary-system;magnetostriction
YANG Jilian ZHANC Baisheng DINC Yongfan China Institute of Atomic Engergy
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Beijing
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ChinaYANG Yingchang ZHANG Xiaodong Peking University
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Beijing
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ChinaPAN Shuming General Research Institute for Non-Ferrous Metals
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Beijing
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China associate professor
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P.O.Box 275
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Branch No.30
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Beijing 102413
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China
金属学报(英文版)
The N occupying sites and magnetic structures in R_2Fe_(17)N_x(R=Y,Dy,Nd)are de- termined by neutron diffraction.The effects of the site occupation of N on magnetic properties are discussed primarily.
关键词:
neutron diffraction
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null
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null
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null
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null
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Journal of Solid State Chemistry
The subsolidus phase relations of R2O3-CaO-CuO ternary systems (R = Nd, Sm, Gd, Tm) have been investigated by X-ray powder diffraction. All samples were synthesized at about 950degrees in air. There exists a ternary compound Ca14-xRxCu24O41 (x = 4 for R = Nd, Gd and x = 5 for R = Sm) and a ternary solid solution Ca2+xR2-xCu5O10 (R = Nd, Sm, Gd, Tm) with a wide composition range Deltax of about 0.6. The compound Ca14-xRxCu24O41 possesses a layered orthorhombic structure and is isostructural to Sr14-xCaxCu24O41. The lattice parameters a and c of the compound are basically independent of the ionic radius of R, while the lattice parameter b and unit-cell volume V decrease substantially with the decrease of the ionic radii of R. The Ca2+xR2-xCu5O10 solid solution is isostructural to Ca2+xY2-xCu5O10, the structure of which is based on an orthorhombic "NaCuO2-type" subcell containing infinite one-dimensional chains of edge-shared square planar cuprate groups crosslinked by the layered cations Ca and R that locate in the inter-chain tunnels. (C) 2002 Elsevier Science (USA). All rights reserved.
关键词:
R2O3-CaO-CuO (R = Nd, Sm, Gd, Tm) systems;phase relations;Ca10R4Cu24O41 (R = Nd, Sm, Gd) structure;Ca2+xR2-xCu5O10 (R = Nd, Sm,;Gd, Tm) structure;ternary-system;approximately 950-degrees-c;high-pressure;superconductivity;diagram;air;er;compatibilities;property;oxide
