材料期刊网

EXPERIMENTAL INVESTIGATION ON HISTORY-DEPENDENCE OF PLASTIC BEHAVIOR OF TYPE 302 STAINLESS STEEL UNDER COMBINED AXIAL-TORSIONAL LOADS

S.X. Zhao , X.F. Sun and Z.B. Kuang (Institute of Applied Mechanics , Southwestern Jiaotong University , Chengdu 610031 , China)(Institute of Engineering Mechanics , Xi'an Jiaotong University , Xi'an 710049 , China)

金属学报(英文版)

Experimental investigations were pedermed on the plastic deformation along bilinear strain paths with various values of corner-angle by subjecting thin-walled tubular specimens of type 302 stainless steel to combined axial and torsional loads. Variations of scalar and vectorial behavior of the stress response are discnssed in the vector space of plastic strain. It is found that the intrinsic geometry of loading path, the plastic strain history and the coapled effect among strain components effect effectively the stress response of the material. The experimental results also show that these effects will disappear gradually with increasing strain.

关键词: complex loading , null , null

DYNAMIC ASPECTS OF LINEAR ELASTIC FRACTURE-MECHANICS APPLIED TO DIELECTRIC-BREAKDOWN

Journal of Physics D-Applied Physics

The dynamic aspects of linear elastic fracture mechanics applied to dielectric breakdown are studied. In the same direction as the fracture mechanics analogue for dielectric breakdown described previously by some researchers, this paper develops the intrinsic, rate-dependent bond breakdown micromechanism to account for the dynamic process of dielectric breakdown. The formulae of conducting microcrack growth rate and lifetime prediction are derived and applied to the experimental data of SiO2 films.

关键词: sio2-films;oxides

Calculations of the spin-lattice coupling coefficients F-ij and Z(ij) for MgO : Co2+ crystal

Communications in Theoretical Physics

According to a uniform and simple method of calculating spin-lattice coupling coefficients and the perturbation formulas of gi factors and hyperfine structure constants Ai based on the cluster approach for 3d(7) ions in Cubic, tetragonal and trigonal octahedral crystal fields, the spin-lattice coupling coefficients F-ij (F-11, F-12, F-44), Z(ij) (Z(11), Z(12), Z(44)) and also g factor and hyperfine constant A for MgO:Co2+ are calculated by using the parameters obtained from the optical spectra without adjustable parameters. The calculated results show good agreement with the observed values. The difficulty in explaining the coefficients F-ij and Z(ij) is therefore removed.

关键词: spin-lattice coupling coefficients;electronic paramagnetic resonance;crystal- and ligand-field theory;Co2+;MgO crystal;superposition model;explanation;symmetry;ions;co2+;g11;g44

基于临界区加速冷却的(B+F)X80大变形管线钢的组织和性能研究

马晶 , 张骁勇 , 程时遐 , 高惠临

材料导报

采用热模拟、力学性能测试和材料显微分析等试验技术,对X80管线钢在临界区加速冷却工艺下的组织性能变化规律进行了研究.结果表明,通过临界区加速冷却,X80管线钢可获得贝氏体+铁素体(B+F)双相组织.随着始冷温度的上升,试验钢的贝氏体含量增加,铁索体含量降低,导致屈服强度增高,塑性降低.当始冷温度为840℃时,显微组织以细小、多位向分布的贝氏体为主,辅以高密度位错的多边形铁素体.这种(B+F)双相组织使得试验钢的屈强比为0.80、均匀伸长率为10.0％、形变强化指数为0.12,满足了大变形管线钢的技术要求.

关键词: X80大变形管线钢 , 临界区加速冷却 , 始冷温度

钛等金属的SUN-Z-R复合技术

吴全兴

钛工业进展 doi:10.3969/j.issn.1009-9964.2001.02.008

关键词:

Structural evolution of Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors

Journal of Applied Physics

Structural parameters have a critical impact on superconductivity in iron-based oxypnictide superconductors. Structural evolution study was performed on Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by the analysis of the x-ray diffraction patterns with Rietveld refinement. Substitution of Gd for Ce generates internal pressure that compresses the crystal lattice. The contraction of the c axis is also indicated by the reduction of Ce/Gd-As and Ce/Gd-O/F distances, while there is a slight increase in the As-Fe-As block size, which is compensated by a large reduction in the Ce/Gd-O/F-Ce/Gd block with Gd substitution. The diagonal Fe-As-Fe angle for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16), with the highest T(c) among Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds, is 111.13 degrees. It is close to the ideal value of 109.47 degrees for the perfect FeAs tetrahedron, which is situated in the region of Fe-As-Fe bond angles where RFeAsO compounds tend to have the highest T(c). (C) 2011 American Institute of Physics. [doi:10.1063/1.3565408]

关键词: layered quaternary compound;high-temperature superconductivity

Study of properties of mixed ferro-ferrimagnetic ising compounds with (A(x)B(1-x))(y)C

Communications in Theoretical Physics

The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A(x)B(1-x))(y)C-z where A(z) B-z and C are three different magnetic ions and form three different sublattices, are studied by using the standard mean-field theory. The phase diagram which is related to experimental work of molecule-based ferro-ferrimagnet ((NixMn1-xII)-Mn-II)(1.5)[Cr-III(CN)(6)].zH(2)O is obtained. The magnetization curves(z) internal energy(z) and specific heat of the same mixed (A(x)B(1-x))(y)C system are also investigated.

关键词: mixed ferro-ferrimagnet;Ising model;phase diagram;internal energy;specific heat;mean-field analysis;magnetic-properties;prussian blue;alloy

AN UNIDENTIFIED MAGNETIC TRANSITION IN R2FE14X COMPOUNDS (R = SM, TB, DY, HO, ER, AND TM - X = B OR C)

Journal of Applied Physics

In Ho2Fe14B and Ho2Fe14C the temperature dependence of the ac initial susceptibility between 4.2 and 300 K shows two peaks. The peak at the lower temperature can be explained by a well-known spin reorientation transition (at 62 K for Ho2Fe14B and at 40 K for Ho2Fe14C). The peak at the higher temperature (at 245 K for Ho2Fe14B and at 265 K for Ho2Fe14C) disappears when the external field is applied parallel or perpendicular to the preferential direction of a magnetically aligned sample. The similar peak was also traced for R2Fe14X compounds (R = Sm, Tb, Dy, Ho, Er, and Tm; X = B or C). Searching for the nature of this peak traced by measuring the temperature dependence of the ac susceptibility for 3d-4f compounds is still under progress.

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Structural and magnetic properties of Laves compounds Dy1-xPrx(Fe0.35Co0.55B0.1)(2) (0 <= x <= 1)

Journal of Applied Physics

Dy1-xPrx(Fe0.35Co0.55B0.1)(2) (0 <= x <= 1) Laves compounds with a cubic MgCu2-type structure were synthesized by arc melting and subsequent annealing. The lattice parameter of the Laves compounds linearly increases, while the Curie temperature T-C decreases with increasing Pr content. The saturation magnetization M-s at 5 K or 295 K for the Dy1-xPrx(Fe0.35Co0.55B0.1)(2) alloys decreases to reach a minimum, then increases with increasing Pr content. The composition for magnetic moment compensation is about x=0.55 at 295 K and x=0.65 at 5 K, respectively. The magnetostriction lambda(parallel to) or lambda(perpendicular to) at room temperature was investigated either parallel or perpendicular to the applied field using a standard strain gauge technique. (C) 2006 American Institute of Physics.

关键词: spontaneous magnetostriction;alloys;prfe2;boron

X状Z-pin增强泡沫夹层结构的剪切性能

杜龙 , 矫桂琼 , 黄涛 , 赵龙 , 黄峰

复合材料学报 doi:10.3321/j.issn:1000-3851.2007.06.024

通过不同Z-pin角度(15°和25°)和夹芯厚度(8mm和12.7mm)的X状Z-pin增强泡沫夹层材料的剪切性能试验,与相同材料同尺寸的未增强件进行对比,考察X状Z-pin对泡沫夹层结构的增强作用.试验结果表明,X状Z-pin增强使材料的剪切强度和刚度都有较大幅度的提高;同时,Z-pin的加入使该结构具有与传统泡沫夹层材料不同的剪切破坏形式.在此基础上,结合空间网架结构和等效夹杂方法,提出了X状Z-pin增强泡沫夹层结构剪切刚度模型,计算结果与试验值符合良好.结果表明,X状Z-pin增强不仅能大幅度提高泡沫夹层结构的剪切性能,并具有良好的可设计性,可以通过改变Z-pin角度和材料等改变其力学性能.

关键词: 夹层结构 , Z-pin增强 , 剪切性能