材料期刊网

DIRECT SYNTHESIS OF SIA LON/ SiC MULTIPHASE REF RACTORY USING CLAY

H. Q. Ru1) , N. Zhang2) , P. Z. Yu1) and X. D. Sun1)1) Northeastern University , Shenyang 110006 , China2) Shenyang University , Shenyang 110044 , China

金属学报(英文版)

Sialon/ Si C m ultiphase refractory w as directly synthesized using cheap clay , Si C particlesand proper ad ditives . The new synthesizing process is si m ple an d of low cost . The synthesizedm aterial has good roo m tem perature m echanical properties and ther m al shock resistance . Thisw ork has provided the experi mental basis for the ap plication of high property an d cheap Sialon/ Si C m ultiphase refractories .

关键词: clay , null , null

THE SYNTHESIS AND MAGNETOSTRICTION OF P rx Ce 1 x Fe 2 COMPOUNDS

Y.X.Li , G.Z.Xu , J.P.Qu , F.G.Liu and B.W.Wang Hebei University of Technology , Tianjin 300130 , China C.C.Tang.G.H.Wu and W.S.Zhan State Key Laboratory for Magnetism , Institute of Physics , CAS , Beijing 100080 , China C.Zhao Tianjin University , Tianjin 300072 , China S.X.Gao Hebei Normal University , Shijiazhuang 050091 , China

金属学报(英文版)

The synthesis and magnetic properties of Pr xCe 1 x Fe 2 have been investigated. The forma tion of Pr xCe 1 x Fe 2 is found to depend strongly on annealing temperature. Pure single phase compound can be synthesized at ambient pressure when x≤0 5. The main phase of the Laves structure can still be observed up to x=0 8. Magnetostriction increases with in creasing x and a largest saturation magnetostriction 200 ppm is observed for x=0.5.

关键词: magnetostriction , null , null

X70管线钢J1d和K1a与V型缺口Ak关系研究

朱杰武 , 柳永宁 , 许雁 , 冯耀荣

机械工程材料 doi:10.3969/j.issn.1000-3738.2005.06.007

在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.

关键词: 管线钢 , 断裂韧度 , 止裂韧度 , 韧-脆断裂转变

Magnetocaloric effect and size-effect related thermal hysteresis reduction in MnAs(1-x)P(x) compounds

Physica Status Solidi a-Applications and Materials Science

In MnAs(1-x)P(x) compounds (x = 0.006 and 0.01), prepared by mechanical alloying, the thermal hysteresis is greatly reduced from about 10-30K in MnAs-based compounds, prepared by conventional melting, to 2K for x = 0.01 (or 4K for x = 0.006). Such obvious hysteretic reduction is ascribed to the grain-size effect, largely due to the preparation method of mechanical alloying. Meanwhile, a maximum value of the magnetic-entropy change Delta S(M) of 11.3 J/kgK for a field change of 2 T is obtained at 294.5K for MnAs(0.994)P(0.006). The study on the MnAs(1-x)P(x) system and also the effect of the preparation technology may be beneficial for the realization of magnetic refrigerants for application at room temperature. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词: magnetocaloric effect;mechanical alloying;thermal hysteresis;gd-5(si2ge2);transition;mnas

Subsolidus phase relation and crystal structure in the Pr(1+x-y)Ba(2-x-z)Ca(y+z)Cu(3)O(7 +/-delta) system

Applied Physics a-Materials Science & Processing

The Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution was investigated by means of X-ray powder diffraction combined with Rietveld analysis. A Pr123 single phase could be synthesized under Pr-rich conditions by sintering at 950 degreesC in air. The solubility range of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution is 0.08 less than or equal to x less than or equal to 0.80. The structure of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) for 0.08 less than or equal to x less than or equal to 0.30 is orthorhombic. The structure transforms into tetragonal for 0.30 less than or equal to x less than or equal to 0.80. To form the Pr123 single phase, the Ba sites in the Pr123 structure must have partial Pr ions, and the least amount is x = 0.08. Ba ions cannot occupy the sites of Pr ions. In the Pr123 structure, Ca ions can replace Pr ions; the highest value is x = 0.4 in the PrBa(2-x)Ca(x)Cu(3)O(7+/-delta) system under our experimental conditions. However, Ca ions cannot replace B a ions. The ionic radius plays a more important role than the chemical properties in the substitution between Pr, Ba and Ca ions in the Pr123 structure.

关键词: cu-o system;approximately 950-degrees-c;superconductivity;diagram;pr;growth;nd;prba2cu3o7-delta;praseodymium;property

Magnetomechanical properties of epoxy-bonded (Tb(0.3)Dy(0.7))(1-x)Pr(x)Fe(1.55) (0 <= x <= 0.4) pseudo-1-3 magnetostrictive composites

Journal of Physics D-Applied Physics

Pseudo-1-3 magnetostrictive composites consisting of stabilizer ( B, Co)-free, light rare earth (Pr)-containing magnetostrictive (Tb(0.3)Dy(0.7))(1-x) Pr(x) Fe(1.55) (0 <= x <= 0.4) particles with a size distribution of 10-300 mu m embedded and aligned in a passive epoxy matrix using 0.5 volume fraction are fabricated. The quasistatic magnetomechanical properties of the composites are investigated and compared with their monolithic (Tb(0.3)Dy(0.7))(1-x) Pr(x) Fe(1.55) alloys, as a function of the Pr content x. The composites show similar qualitative trends in properties with the alloys for all x. The (Tb(0.3)Dy(0.7))(0.75)Pr(0.25)Fe(1.55) composite and alloy exhibit the smallest coercivity H(c), the largest magnetostriction lambda and the highest piezomagnetic coefficient d(33) due to the successful compensation for magnetocrystalline anisotropy. The ( Tb0.3Dy0.7) 0.75Pr0.25Fe1.55 composite demonstrates a large saturation magnetostriction lambda(s) of 793 ppm at 700 kAm(-1) and a high d(33) of 3.2 nmA(-1) at 140 kAm(-1). These values approach 81% and 85% of its alloy values at the same field levels. The good properties make the (Tb(0.3)Dy(0.7))(0.75)Pr(0.25)Fe(1.55) composite and alloy a promising magnetostrictive material system.

关键词: terfenol-d;magnetic-properties;alloys;boron

Magnetomechanical properties of epoxy-bonded Sm(1-x)Nd(x)Fe(1.55) (0 <= x <= 0.56) pseudo-1-3 magnetostrictive particulate composites

Journal of Alloys and Compounds

Pseudo-1-3 magnetostrictive particulate composites consisting of light rare earth (Sm and Nd)-based magnetostrictive Sm(1-x)Nd(x)Fe(1.55) particles with the Nd content x of 0-0.56 and randomly distributed sizes of 10-180 mu m membedded and aligned in a passive epoxy matrix are fabricated using the particulate volume fraction of 0.5. The quasistatic magnetomechanical properties of the composites are investigated and the results are compared with their monolithic alloys for various x. The composites exhibit similar qualitative trends in properties with the alloys for all x. The Sm(0.92)Nd(0.08)Fe(1.55) composite shows a large unsaturated magnetostriction lambda of -530ppm at 500 kA/m and a high piezomagnetic coefficient d(33) of -2.0 nm/A at 100 kA/m as a result of the magnetocrystalline anisotropy compensation between Sm(3+) and Nd(3+) ions in the Sm(0.92)Nd(0.08)Fe(1.55) alloy. (C) 2011 Elsevier B.V. All rights reserved.

关键词: Light rare earths;Magnetocrystalline anisotropy;Magnetomechanical;properties;Negative magnetostriction;Magnetostrictive composites;Sm(1-x)NdxFe(1.55) alloys;terfenol-d

First-principles study on the electronic structure of dilute magnetic semiconductor Ga(1-x)Cr(x)P in zinc-blende phase

Physica Status Solidi B-Basic Research

We employ the full potential linearized augmented plane wave (FP-LAPW) method based on spin-polarized density functional theory (DFT) in order to investigate the structural, electronic, and magnetic properties of ordered dilute magnetic semiconductor (DMS) Ga(1-x)Cr(x)P in zinc-blende phase. The calculated electronic band structures and density of states of these DMSs are discussed. The results show that the ferromagnetic states are more favorable in energy than antiferromagnetic states. Ga(1-x)Cr(x)P for x = 0.125, 0.25, and 0.50 exhibits half-metallic (HM) characteristic with integral magnetic moment, and the sensitivity of half-metallicity of Ga(1-x)Cr(x)P as a function of lattice constant is also discussed. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词: dilute magnetic semiconductors;density functional theory;electron;density of states;GaCrP;half-metallic ferromagnets;heusler alloys;doped gap;spin;gaas;ge;al;si

Z型铁氧体Ba_3（MnZn）_xCo_（2（1-x））Fe_（24）O_（41）的微波吸收性能

周克省 , 陈颖 , 秦宪明 , 邓联文 , 夏辉 , 黄生祥 , 卢玉娥 , 齐伟 , 韩建华

功能材料

用溶胶-凝胶法制备锰锌掺杂Z型钡钴铁氧体Ba3（MnZn）xCo2（1-x）Fe24O41（x=0.0、0.1、0.2、0.3、0.4、0.5）样品。用XRD和SEM对样品的晶体结构、颗粒形貌进行表征,用微波矢量网络分析仪测试该样品在2～18GHz微波频率范围的复介电常数、复磁导率,根据测量数据计算电磁损耗角正切及反射率,探讨该材料的微波吸收性能与电磁损耗机理。结果表明样品为Z型六角铁氧体晶体结构,颗粒呈六角片状形貌;当样品厚度为2.2mm、x=0.4时,在频率3.9GHz处吸收峰值为38.5dB,10dB以上频带宽度为3.8GHz;该材料能在1～5.8GHz微波低频范围实现有效吸收,其微波吸收兼具磁损耗和介电损耗,但磁损耗更为显著。

关键词: 溶胶-凝胶法 , Z型钡铁氧体 , 微波吸收 , 电磁损耗

三元GaxIn1-xP和四元(AlxGa1-x)0.51In0.49P合金拉曼光谱研究

吕毅军 , 高玉琳 , 郑健生 , 李志锋 , 蔡炜颖 , 王晓光

功能材料与器件学报 doi:10.3969/j.issn.1007-4252.2000.04.024

测量了室温下三元GaxIn1-xP (x=0.48)和四元(AlxGa1-x)0.51In0.49P (x=0.29)合金背散射配置下的喇曼光谱. 三元GaxIn1-xP的喇曼谱表现为双模形式, 在DALA带上叠加了FLA模, 在有序样品中观察到了类GaP的TO1模和类InP的TO2模, 类GaP的LO1模和类InP的LO2模的分裂, 表示有序度的b/a比从无序样品的0.40变化到有序样品的0.10, 有序样品b/a比的降低是由于TO1模和LO1模分裂的影响所造成的. 四元(AlxGa1-x)0.51In0.49P为三模形式, 观察到了双峰结构的FLA模, 由于Al组分的影响, 类GaP的LO模成了类InP的LO模的肩峰. 所有模式与经验公式吻合得很好.

关键词: 喇曼谱 , 有序化 , Ⅲ-Ⅴ族半导体