材料期刊网

INFLUENCE OF MOULD ROTATION ON MACROSEGREGATION IN INGOT

YU Qiuping ZHOU Yaohe Northwestern Polytechnical University , Xi'an , China [Originally published in ACTA METALL SIN (CHINESEEDN) 24 (5) 1988pp B307—B312 , received 27 December 1986 , in revised form 7 December 1987]

金属学报(英文版)

The macrosegregation formation in an ingot and the influence of rotating mould upon it were analysed on the basis of interdendritic flow.When the ingot mould rotates unidirectionally,the centrifugal volume force acts on all inner parts,and when the ingot mould rotates alternately, the tangential alternate force is also formed,and both have various influences on the different modes of interdendritic flow.It is shown that as the ingot mould rotates unidirectionally or alternately with a moderate angular speed,the interdendritic unstable flow may be controlled effectively and the formation of segregation may be restrained.Thus,it seems to be significant for reducing the segregation such as A-type etc.,in the steel ingot.

关键词: ingot , null , null

硼酸酯改性Mg2B205w／PP复合材料

陈善华 , 吴永嘉 , 金培鹏

材料科学与工艺

为了提高聚丙烯（PP）的强韧性能，采用熔融共混法分别制备了质量分数为0～15％的Mg2B2O5晶须（MBOw）和硼酸酯偶联剂（BE）改性MBOw填充PP基复合材料，测试了PP及其复合材料的拉伸、冲击性能，并通过红外光谱、接触角测试、扫描电镜分析等对复合材料界面作用机理进行了研究，结果表明：MBOw与BE之间存在化学和物理吸附层；PP与BE处理前后的MBOw之间不存在化学键合；BE改性MBOw／PP复合材料中PP与MBOw之间的粘附功和表面张力之比由BE表面处理前的8．7增至处理后的315.0，明显改善了基体中MBOw的分散性及其界面结合性能，提高了BE改性MBOw／PP复合材料的拉伸及冲击性能。

关键词: 硼酸镁晶须 , 硼酸酯偶联剂 , 聚合物基复合材料 , 界面结合 , 力学性能

Formation of glassy Ti50Cu20Ni24Si4B2 alloy by high-energy ball milling

Materials Letters

The elemental powder mixtures with a nominal composition of Ti50Cu20Ni24Si4B2 can be amorphized under high-energy ball milling. A well-defined glass transition before crystallization appears in the obtained amorphous phase during heating in a differential scanning calorimeter. A wide supercooled liquid region DeltaT(x) is available to be about 57 K. Crystallization of the ball-milled amorphous phase was performed through one step to form the metastable (Ni, Cu)Ti phase with cubic structure and an unknown phase, followed by subsequent grain growth. The reduced glass transition temperature of the alloy was determined to be 0.56. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词: mechanical alloying;metallic glasses;supercooled liquid;titanium;supercooled liquid region;amorphous-alloys;mechanical-properties;thermal-stability;cu-ni;crystallization

高能球磨形成具有明显玻璃转变的Ti50Cu20Ni24Si4B2非晶态合金

张来昌 , 徐坚

金属学报

在高能球磨作用下,名义成分为Ti50CU20Ni24Si4B2的元素粉末混合物可通过固态反应非晶化.差示扫描量热分析(DSC)表明,球磨获得的非晶相在发生晶化转变之前出现明显的玻璃转变,过冷液态温度区间的宽度(△Tx)可达到57 K.非晶态Ti50CU20Ni24Si4B2合金加热时的晶化转变由一步完成,同时形成立方结构的(Ni,Cu)Ti相和其它未知相,为共晶型转变,随后发生晶化产物的进一步晶粒长大.非晶态Ti50Cu20Ni24Si4B2合金的约化玻璃转变温度(Trg)为0.56.

关键词: 钛.非晶态台金.过冷液体 , null

高能球磨形成具有明显玻璃转变的Ti50Cu20Ni24Si4B2非晶态合金

张来昌 , 徐坚

金属学报 doi:10.3321/j.issn:0412-1961.2002.03.017

在高能球磨作用下,名义成分为Ti50CU20Ni24Si4B2的元素粉末混合物可通过固态反应非晶化.差示扫描量热分析(DSC)表明,球磨获得的非晶相在发生晶化转变之前出现明显的玻璃转变,过冷液态温度区间的宽度(△Tx)可达到57 K.非晶态Ti50CU20Ni24Si4B2合金加热时的晶化转变由一步完成,同时形成立方结构的(Ni,Cu)Ti相和其它未知相,为共晶型转变,随后发生晶化产物的进一步晶粒长大.非晶态Ti50Cu20Ni24Si4B2合金的约化玻璃转变温度(Trg)为0.56.

关键词: 钛.非晶态台金.过冷液体 , 机械合金化

Na5[B2P3O13]晶体双晶结构的研究

李志华 , 傅佩珍 , 吴以成 , 陈创天

人工晶体学报 doi:10.3969/j.issn.1000-985X.2003.06.021

采用泡生法和b向籽晶生长出尺寸为22mm×24mm×20mm的透明Na5[B2P3O13]晶体.晶体定向中发现(100)和(001)晶面的一级衍射出现双峰;正交偏光显微镜下观察晶体的(010)切片,看到清晰的明暗条纹;当一束激光正入射(010)切片时,产生衍射现象;用同步辐射白光X射线形貌术拍摄了(100)、(010)和(001)切片的Laue像,观察到了晶体的孪晶结构,再借助(010)切片的化学腐蚀研究,推出该晶体为规则的聚片双晶,其结合面为(001).

关键词: Na5[B2P3O13]晶体 , 双晶 , 同步辐射X射线白光形貌术 , 激光衍射

Superposition model parameters (b)over-bar(2) and t(2) for d(5) ion Cr+ in sulfides

Physica B-Condensed Matter

The superposition model has been applied to the studies of the zero-field splitting b(2)(0) for AgGaS2: Cr+ crystal and the uniaxial stress EPR data for ZnS: Cr+ crystal. These studies show that for [CrS4](7-) groups in crystals, the intrinsic parameter (b)over-bar(2)(R-0) approximate to -0.035(8)cm(-1) with the reference distance R-0 approximate to 2.378(20) Angstrom and the power-law exponent t(2) approximate to 14(4). To our knowledge, this is the first time that the superposition model parameters (b)over-bar(2) and t(2) are given for Cr+-S2- combination (or other Crc-X combinations). (C) 1999 Published by Elsevier Science B.V. All rights reserved.

关键词: electron paramagnetic resonance;superposition model;Cr+ ion;AgGaS2;ZnS;zero-field splittings;crystals;transition;mn-2+;fe-3+

B位Co掺杂对Sr14Cu24O41的结构和电输运的影响

林颖 , 魏伟 , 熊锐 , 胡妮 , 汪丽莉 , 余祖兴 , 汤五丰 , 石兢

低温物理学报 doi:10.3969/j.issn.1000-3258.2007.04.003

采用固相反应法制备了系列Sr14(Cu1-xCox)24O41(x=0,0.02,0.06,0.1,0.14,0.18)的样品,X-射线衍射结果显示所有样品均为单相,且Co的掺杂几乎不改变样品的晶格常数,电子衍射和X-射线光电子能谱的测量结果证实Co替代的是链上的Cu原子;电输运的测量显示,Co掺杂样品表现为半导体行为,且渡越温度T 随掺杂量的增加逐渐减小.

关键词: 强关联 , Sr14Cu24O41 , 自旋梯状结构 , 电输运

Structural transition, electrical and magnetic properties of the B-site Co doped Sr(14)Cu(24)O(41) compounds

Journal of Physics-Condensed Matter

The effect of Co substitution for Cu on the structure and physical properties of Sr(14)(Cu(1-x)Co(x))(24)O(41) compounds was studied by analyzing the selected-area electron diffraction and convergent-beam electron diffraction patterns, and by measuring the magnetic susceptibility, the electrical resistivity and Raman spectra. It is found that the space group of the CuO(2) chain is changed from Amma to Ammm upon Co doping, but the structure of the Cu(2)O(3) ladder remains unchanged. This indicates that the displacement between two neighboring CuO(2) chains has disappeared due to Co doping. Once a small amount of Co ions are doped into the compound, exceptional changes in the Weiss temperature and in the number of dimers occur. The remarkable increase in the absolute value of the Weiss temperature indicates that the antiferromagnetic interaction in CuO(2) chains becomes very strong due to Co doping. The increase in the Curie coefficient and the number of dimers implies that the Co doping causes Zhang-Rice singlets in the chains to be decoupled into free spins Cu(2+) and holes. Then, the free spins Cu(2+) are coupled into dimers, and the holes transfer from chains to ladders, which causes the resistivity to decrease when the Co dopant concentration is low (x < 0.10). When the Co dopant concentration is high ( x > 0.10), some Co ions are directly substituted for the Cu ions in the ladders, which results in an increase in resistivity with increasing Co dopant content.

关键词: raman-active phonons;spin-ladder;chain compounds;sr(14-x)a(x)cu(24)o(41);la;substitution;gap;ca;resistivity;dynamics

Synthesis, structure, and magnetic properties of Pr5Co19B6

Physical Review B

A compound Pr5Co19B6 has been synthesized successfully and its crystal structure has been investigated by x-ray powder diffraction. It belongs to the Rm+nCo5m+3nB2n (R = rare earth) family with m = 2 and n = 3. The space group is P6/mmm. The lattice parameters are alpha = 5.1264(4) Angstrom and c = 16.5602(6) Angstrom. Each unit cell contains one formula unit of Pr5Co19B6, and there are nine kinds of equivalent positions in each unit cell, i.e., 1b, 2e(1), 2e(2), 4h(1), 6i(1), 6i(2), 3f, 2d, and 4h(2), which are occupied by 1Pr((1)), 2Pr((2)), 2Pr((3)), 4Co((1)), 6Co((2)), 6Co((3)), 3Co((4)), 2B((1)), and 4B((2)), respectively. Magnetic measurements indicate that this compound is ferromagnetic with a Curie temperature of 380 K. Its saturation magnetic moment at 5 K and room temperature an 23.7 mu(B) /f.u. and 11.9 mu(B) /f.u., respectively. Based on the experimental results of the saturation magnetization, three kinds of Co sites with different magnetic moment are proposed. The Pr5Co19B6 compound exhibits huge planar anisotropy with an anisotropy held of 250 kOe at 5 K. No spin reorientation was detected from the temperature dependence of the magnetization and the temperature dependence of the ac susceptibility curves from 5 FC to room temperature. The behavior of magnetocrystalline anisotropy is analyzed using the single-ion model.

关键词: anisotropy;system;field;gd