Z.C. Guo
,
X.Y. Zhu
金属学报(英文版)
The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE (rare earth)-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with increasing
pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of
RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r = 0.8 is higher than that at r = 0.6.
关键词:
pulse frequency
,
null
,
null
Z.C. Guo
,
X.Y. Zhu
,
R.D. Xu
金属学报(英文版)
Cathodic deposition current density of the composite coatings increases when SiC par-ticles and rare earth (RE) were added in the bath, which is profitable for Ni- W-P alloyto deposit in the cathod, forming Ni-W-P-SiC and RE-Ni-W-P-SiC composite coat-ings. On the contrary, the addition of PTFE in the bath decreases cathodic depositioncurrent density of the coatings. The current density increases a little when the amountof RE is 7-9g/l; however, the current density increases greatly when the amount ofRE is increased to 11-13g/l. But if the amount of RE is raised further, the currentdensity decreases. Hardness and wear resistance of RE-Ni-W-P-SiC composite coat-ing have been studied, and the results show that the hardness and wear resistance ofRE-Ni-W-P-SiC composite coating increase with increasing heat treatment tempera-ture, which reach peak values at 400℃; while the hardness and wear resistance of thecoating decrease with the rise of heat treated temperature continuously.
关键词:
electrodeposition
,
null
Applied Physics Letters
The effect of nonmagnetic Y partial substitution at the Dy site in Dy(1-x)Y(x)MnO(3) up to x=0.2 on magnetism, specific heat, and ferroelectricity is investigated, which resulted in a preliminary multiferroic phase diagram. It is revealed that the Y partial substitution suppresses the Dy-spin ordering point (T(Dy)) and ferroelectric ordering point (T(FE)) but enhances the Mn-spin ordering point (T(N)). The interaction between the spins of Dy and Mn is remarkably affected by Y substitution. The measured electrical polarization depends on the Y substitution in a complex way because the ferroelectricity is sensitive to the interaction between the spins of Dy and Mn. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3536506]
关键词:
ferroelectricity;polarization
材料科学技术（英文）
The glass-forming ability (GFA) of Nd(70-x)Fe(20)Al(10)Y(x) and Nd(60-x)Fe30Al(10)Y(x) (0 less than or equal to x less than or equal to15) alloys produced by Cu mold casting was investigated. Except Y = 5 at. pct, bulk amorphous Nd(70-x)Fe(20)Al(10)Y(x) alloys up to 2 mm in diameter were obtained. The GFA for Nd(60-x)Fe(30)Al(10)Y(x) alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd(60)Fe(30)Al(10) alloy. The Nd(60)Fe(20)Al(10)Y(10) and Nd(60)Fe(30)Al(10) alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd(55)Fe(20)Al(10)Y(15) alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, T(g), and the supercooled liquid region, DeltaT(x), are 776 K and 58 K, respectively, The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.
关键词:
Nd-based alloys;glass forming ability;liquidus temperature;thermal;stability;supercooled liquid region;bulk amorphous-alloys;metallic glasses;transition temperature;thermal-stability;atomic size;ni alloys;cu;alloys;diameter;tm
Physica B-Condensed Matter
The magnetic properties and magnetocaloric effect of Tb(1-x)Y(x)CoC(2) (x = 0, 0.1, 0.2, 0.3, 0.4) compounds have been investigated systematically. All the compounds undergo second-order transitions from paramagnetic to ferromagnetic states without thermal and magnetic hysteresis. With increasing Y content from 0 to 0.4, the Curie temperatures decrease nearly linearly from 28 to 18 K. The nature of the second-order phase transitions can be confirmed by Arrott plots. For Tb(0.6)Y(0.4)CoC(2) compound, the maximum value of the magnetic entropy change -Delta S(M) at 20 K is 9.35 J kg(-1) K(-1) for an external field change of 5T (5.14 J kg(-1) K(-1) for 2T). The large reversible magnetic entropy change makes Tb(0.6)Y(04)CoC(2) compound an attractive candidate for the application at hydrogen liquefaction temperature. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
Curie temperature;Magnetocaloric effect;Magnetic properties;ac susceptibility
Materials Letters
The dynamic hysteresis in a planar X-Y model as a function of frequency and amplitude of external field, at a temperature far below its Curie point, is studied by means of Monte Carlo (MC) method. The evolution of hysteresis dispersion is simulated in details and the earlier proposed scaling on the hysteresis dispersion is confirmed in the present system. It is predicted that the unique characteristic time for domain reversal is inversely proportional to the field amplitude once the amplitude is not very small. (C) 2002 Elsevier Science B.V. All rights reserved.
关键词:
dynamic hysteresis;scaling;planar X-Y model;kinetic ising-model;magnetic hysteresis;phase-transition;films
Journal of Physical Chemistry C
We report the electrical, thermal, magnetic, and thermoelectric properties of Y-doped Ca(3)Co(4)O(9) from 300 down to 5 K. The results indicate that with Y doping, the increase of resistivity originates from the decreases of carrier concentration and mobility, while the increase of Seebeck coefficient is caused by the reduction of carrier concentration together with the enhanced electronic correlation. Point-defect scattering, is the dominant thermal transport mechanism in this system. Due to the considerable difference in mass between Y(3+) and Ca(2+), thermal conductivity is observably suppressed by doping. The substitution of Y also disturbs the interlayer ferrimagnetic coupling. The ground state of this System converts front ferrimagnetism to paramagnetism gradually. The alteration of transport properties of Ca(3-x)Y(x)Co(4)O(9) reveals two Crossovers: the transition from Fermi-liquid-like metal to thermally activated semiconductor occuring at x approximate to 0.25, and the transition from thermally activated semiconductor to two-dimensional variable range hopping semiconductor occurring at x approximate to 0.5. The optimal thermoelectric response In Ca(3-x)Y(x)Co(4)O(9) is found to exist only at the critical state after which the doping-induced metal-insulator transition takes place. Oil the basis of these experimental results, a possible phase diagram for Ca(3-x)Y(x)Co(4)O(9) is proposed.
关键词:
temperature thermoelectric properties;giant magnetoresistance;solid-solutions;conductivity;electron;system;ca3co4o9+delta;thermopower;crystals;behavior
Ieee Transactions on Magnetics
The spin orientation and spontaneous magnetostriction of multicomponent TbxDy1-x-yPry(Fe0.9B0.1)(1.93) (0.10 less than or equal to x less than or equal to 0.25, 0.30 less than or equal to y less than or equal to 0.60) Laves phases were studied by step-scanning their (440) X-ray diffraction lines. The easy magnetization direction (EMD) of the Laves phases changed from the (100) to (111) axis when x was increased from 0.10 to 0.25. With increasing y, the EMD of Tb0.15Dy0.85-yPry(Fe0.9B0.1)(1.93) and Tb0.2Dy0.8-yPry(Fe0.9B0.1)(1.93) Laves phases reoriented from the (100) to (111) axis. The magnetostriction coefficient lambda(111) of TbxDy1-x-yPry(Fe0.9B0.1)(1.93) Laves phases increased with increasing x (or y) when y (or x) was kept constant.
关键词:
Laves phases;magnetostriction;spin orientation;X-ray diffraction;anisotropy compensation;alloys
