材料期刊网

THE COMPUTATION AND EXPERIMENT ANALYSIS OF ELECTROMAGNETIC CONTINUOUS CASTING WITH SOFT-CONTACTED MOULD

K. Deng , Z.M. Ren , Y.B. Zhong , G.C. Jiang and S.M.Hu 1) School of Materials , Shanghai University , Shanghai 200072 , China 2) Shanghai BAOSTEEL Group , Shanghai 200941 , China

金属学报(英文版)

In this paper, coupling the quasi-3D numerical simulation of electromagnetic field and the experiments of continuous casting with soft-contacted mould with some metals such as tin, aluminum, copper and steel, the electromagnetic characteristics of continuous casting with soft-contacted mould is analyzed. It is shown that the electromagnetic pressure on the surface of billet is increasing with the rising of power frequency as a logarithmically parabolic function, with that of electric conductivity of billet as a power junction, and with that of the current in inductor as a parabolic junction.

关键词: continuous casting (CC) , null , null , null , null

Secondary M6C precipitation in K40S cobalt-base alloy

Materials Letters

Secondary M,C precipitation was investigated in K40S cobalt-base alloy after 100 h aging at 950 degreesC. The results showed that it was closely related to the tungsten-rich zones inherited from the as-cast condition and the degeneration of the primary M7C3 carbide. A direct element reaction, 6M + C --> M6C, in which C comes from the decomposition of the M7C3 carbides, is suggested as the mechanism of secondary M6C precipitation in K40S alloy. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: M6C precipitation;aging;M7C3 carbide;superalloy

Fe-C合金M_s的热力学计算及马氏体相变驱动力

徐祖耀 , 张鸿冰 , 罗守福

金属学报

为适合电子计算机进行计算,本文将各学者的ΔG_(Fe)~(γ→α)值公式化。应用各种ΔG~(γ→α)的计算模型,如经修正的Fisher,KRC和LFG模型,引入不同的ΔG_(Fe)~(γ→α)值,计算得到Fe-C合金的M_s温度。经比较后发现:M_s的计算值不仅取决于ΔG~(γ→α)的计算模型,而且极大地依赖于ΔG_(Fe)~(γ→α);若按照LFG模型并取Mogutnov的ΔG_(Fe)~(γ→α)值,和按照徐祖耀模型并取Kaufman的ΔG_(Fe)~(γ→α)值,计算所得结果均与M_s的实验值吻合得很好,而徐祖耀模型要比普遍公认的LFG模型简单得多。本文较精确地测定了x_C=0.01—0.05 Fe-C合金的M_s值,它们与Kaufman等人(1962)给出的数据很好吻合。Greninger所得x_C=0.06的M_s实验值看来是偏高的。驱动力的计算值不仅依赖于ΔG~(γ→α)的计算模型,而且还极大地取决于ΔG_(Fe)~(γ→α)值以及所选用的M_s值。计算表明:随含碳量的增加,相变驱动力将单调地增大。

关键词:

液相色谱-串联质谱法检测畜禽产品中维吉尼亚霉素M1和S1残留

邱元进 , 杨方 , 刘正才 , 林永辉 , 刘素珍

色谱 doi:10.3724/SP.J.1123.2012.01020

建立了畜禽产品中维吉尼亚霉素M1和S1药物残留检测的液相色谱-串联质谱分析方法.样品以甲醇-乙腈溶液(1:1,V/v)提取,上清液经0.01 mol/L磷酸二氢铵溶液稀释后,Oasis HLB固相萃取小柱净化,Luna C18色谱柱分离,以乙腈和含0.1％(体积分数)甲酸的5 mmol/L乙酸铵水溶液作为流动相进行梯度洗脱,电喷雾正离子模式电离(ESI+).多反应监测(MRM)模式检测,外标法定量.该方法对两物质线性范围均为0.15～10.O μg/L,相关系数r2均大于0.999；定量下限均为0.25 μg/kg.在不同基质中,0.25、0.50、2.5 μg/kg 3个添加水平的平均回收率范围为71.2％～98.4％,精密度范围为3.6％～15.4％.该方法具有快速简便、灵敏度高、准确性强等特点,适用于畜禽产品中维吉尼亚霉素的检测.

关键词: 液相色谱-串联质谱(LC-MS/MS) , 维吉尼亚霉素M1 , 维吉尼亚霉素S1 , 残留 , 畜禽产品

Transient of alumina oxide scale on beta-NiAl coated on M38G alloy at 950 degrees C

Intermetallics

The phase transformation of alumina formed during oxidation of beta-NiAl coating prepared on M38G alloy by pack cementation was investigated. Oxidation experiments were conducted at 950 degrees C for various times from 2 to 180 min. The phase composition and microstructure of the oxide scales were investigated by using glancing angle XRD, AFM and SEM. The results showed that at the initial oxidation stage needle-like theta-Al2O3 was formed and then it covered the sample surface rapidly. The formation of alpha-Al2O3 grains beneath the theta-Al2O3 layer was favored by depletion of Al in the beta-NiAl coating during oxidation. alpha-Al2O3 preferred growing on the top (ridge) of beta-NiAl grains, which resulted in the formation of net-like alpha-Al2O3 inner layer. With increasing time, theta-Al2O3 transformed to alpha-Al2O3 gradually. After 180 min oxidation, most of alpha-Al2O3 grains transformed into alpha-Al2O3. A mechanism of excessive voids' formation at the oxide/coating interface was also proposed in this paper. (c) 2007 Elsevier Ltd. All rights reserved.

关键词: nickel aluminides, based on NiAl;oxidation;phase transformations;coatings, intermetallic and otherwise;high-temperature oxidation;theta-alpha-al2o3 transformation;behavior;coatings;superalloy;transition;layers

局域规范群C∞(M,G)上不存在有限不变正测度

孙为民 , 陈相松 , 王凡

原子核物理评论 doi:10.3969/j.issn.1007-4627.2001.04.014

研究了对Faddeev-域规范群C∞(M,G)(M为一紧致流形, G为一矩阵李群)上不存在有限的平移不变的正测度.

关键词: Faddeev-Popov 方法 , 局域规范群 , 不变测度

Fe-Ni-C合金马氏体相变驱动力及M_s的计算

李箭 , 徐祖耀

金属学报

选取了三种不同的热力学模型,(1)LFG模型;(2)徐祖耀三元系规则溶液模型;(3)本文处理方法(Fisher-徐模型加Zener参数),计算了Fe-Ni-C合金马氏体相变驱动力,求得马氏体相变驱动力与奥氏体在Ms温度的固溶强化呈线性关系:△G~(a→)M=Aσ_(0.2)(Ms)+908J/mol,对不同模型选取系数A’略有差异.利用所导出的奥氏体在Ms温度时的屈服强度,计算了Fe-Ni-C合金的MS温度,计算结果与以往的实验值符合得很好。

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MAGNETIC PROPERTIES OF Nd_2(Fe_(1-x)M_x)_(14)B(M=C,Si)ALLOYS

XING Feng JIANG Chao HE Wenwang Department of Physics , Peking University , Beijing , China [Originally published in ACTA METALL SIN (CHINESEEDN) 24 (5) 1988pp B348—B352 , received 22 October 1986:in revised form 8 May 1987]

金属学报(英文版)

The magnetic properties of Nd_2(Fe_(1-x)M_x)_(14)B(M=C and Si) compounds have been investi- gated.Substituting Fe by small amount of metalloid C and Si atoms,the compounds are in tetragonal structure and have uniaxial anisotropy.The substitution of C for part of Fe de- creases the Curie temperature of the compounds and the intrinsic coercivity of bond samples at low temperature.The replacement of Fe by Si makes the Curie temperature increase with a maximum at the vicinity of x=0.15.When the range of the content of Si is 0≤x≤0.10,the coercivity distinctly increases at room temperature.from 62.7 kA/m at x=0 to 138.7kA/m at x=0.06,where the residual magnetization has a maximum:in the mean time the saturation magnetization decreases only by a small amount.

关键词: Nd-Fe-B alloy , null , null

Nd_2(Fe_(1-x)M_x)_(14)B(M=C,Si)合金的磁性

邢峰 , 江潮 , 何文望

金属学报

本文研究了Nd_2(Fe_(1-x)M_x)_(14)B的磁性。少量类金属原子C和Si取代部分Fe,能形成四方结构,且具有单轴各向异性。碳取代Fe,使化合物的Curie温度降低,低温下粘结体样品的内禀矫顽力减少;而Si对Fe的取代可使Curie温度升高,并在x=0.15附近达到极大值。含Si样品在0≤x≤0.10范围内,矫顽力显著增加,室温下从x=0的62.7kA/m增加到x=0.06的138.7 kA/m,并且在x=0.06附近,剩磁有一个极值,饱和磁化强度减少不多。

关键词: Nd-Fe-B合金 , magnetic properties , Curie temperature

Short-term oxidation resistance and degradation of Cr(2)AlC coating on M38G superalloy at 900-1100 degrees C

Corrosion Science

High temperature oxidation behavior of the Cr(2)AlC coating was investigated at 900-1100 degrees C. During the oxidation, a continuous Al(2)O(3) scale formed, resulting in the improvement of the oxidation resistance of the substrate. Meanwhile, the oxidation induced depletion of Al within the Cr(2)AlC coating resulted in the transformation of Cr(2)AlC to Cr-C phases. Compared with bulk Cr(2)AlC, the Cr(2)AlC coating possessed similar oxidation behavior, but with higher oxidation rate. This is because a great number of columnar grain boundaries existed in the as-deposited coating, through which oxygen and nitrogen could diffuse inwardly, resulting in the internal oxidation and nitridation. (C) 2011 Elsevier Ltd. All rights reserved.

关键词: Ceramic;Sputtered films;Oxidation;Internal oxidation;high-temperature oxidation;ab-initio calculations;internal;nitridation;phase-transformation;m(n+1)ax(n) phases;cyclic oxidation;base superalloy;k38g superalloy;bulk cr2alc;al-c