材料期刊网

Grain Size Control of Semisolid A356 Alloy Manufactured by Electromagnetic Stirring

Z.Yang , P.K.Seo , C.G.Kang

材料科学技术（英文）

To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.

关键词: Semisolid metal process , null , null , null

添加SeO2对电沉积纳米晶Cu的影响

张含卓 , 江中浩 , 连建设

材料保护 doi:10.3969/j.issn.1001-1560.2007.08.015

采用扫描电镜、X射线衍射等方法,研究了SeO2作为添加剂对直流电沉积纳米晶Cu表面形貌、微观结构和硬度的影响.结果表明,加入O.02 g/L SeO2可使沉积层表面平整致密,沉积Cu层的(111)晶面择优取向程度上升,晶粒尺寸减小至27.9 nm左右,显微硬度升至277 HV,约为粗晶铜硬度的6倍.

关键词: SeO2 , 电沉积 , 纳米晶 , 铜 , 形貌 , 微观结构 , 显微硬度

SNOEK-Ke-K■STER PEAK OF INTERNAL FRICTION IN Fe-P-N ALLOYS

Y.Y.Che , G. Y.Zeng , Y. C. Xu and J. W , Ji(College of Science , Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

The internal friction and precipitate phases of the deformed Fe-P-N alloys have been investigated. It has been found that the ratio of depends on the content of P and the relation holds if the content of N is lower than 30wt.ppm and the content of P is lower than 640wt.ppm. It shows that the intercept K2 is related to the presence of the atomic pairs and clusters of P in the alloy matrix.

关键词: internal friction , null

关于K-p两体问题的相对论修正

王万章 , 张启仁 , 高春媛

原子核物理评论 doi:10.3969/j.issn.1007-4627.2005.04.033

从基本理论出发,导出并求解了含有相对论修正的K介子与质子的两体薛定谔方程.其解可看作有统计解释的波函数.计算了K p的散射长度,结果表明相对论效应是很明显的.

关键词: K-p系统 , 相对论修正 , 散射长度

Crystal structure and thermal properties of compound K(2)Zn(3)(P(2)O(7))(2)

Powder Diffraction

K(2)Zn(3)(P(2)O(7))(2) was synthesized by solid state reaction and its crystal structure was determined by ab initio method from powder X-ray diffraction (XRD) data. The title compound was determined to be orthorhombic with space group P2(1)2(1)2(1), Z=4, and lattice parameters a=12.901(8) angstrom, b=10.102(6) angstrom, and c=9.958(1) angstrom. Values of lattice parameters from 303 to 573 K were measured by temperature-dependent XRD. Thermal expansion coefficients alpha(0), lattice parameters, and cell volume at 0 K were determined to be alpha(0)(a)=1.62327X 10(-4)/K, a(0)=12.855(4) angstrom, alpha(0)(b) = 1.17921 X 10(-4)/K, b(0)=10.070(8) angstrom, alpha(0)(c)=2.62364X 10(-4)/K, c(0)=9.880(4) angstrom, and alpha(0)(V) = 6.599 X 10(-2) /K, V(0) = 1278.967(0) angstrom(3). The specific heat equation as a function of temperature was determined to be C(p)=0.77115 +0.00231 T-1241.60027T(-2)- 1.4133 X 10(-6)T(2) (J/K g), for temperatures from 198 to 710 K. The melting point estimated from the mu-DTA heating curve is 795 degrees C. (C) 2008 International Centre for Diffraction Data. [DOI: 10.1154/1.2992517]

关键词: K(2)Zn(3)(P(2)O(7))(2);structure determination;thermal expansion;coefficient;specific heat;powder-diffraction;refinement;zno

应力比对40CrMnSiMoVA钢P-da/dN-△k曲线 影响研究

李淑兰 , 杨玉芬

兵器材料科学与工程 doi:10.3969/j.issn.1004-244X.2008.03.016

在介绍40CrMnSiMoVA钢的力学性能和试验条件基础上,根据金属材料疲劳裂纹扩展的统计分析方法,求出Pa-N和P-da/dN-△k曲线,并对不同应力比条件下的试验数据进行可靠性分析和比较,探讨中值da/dN-△k曲线和99.9%可靠度dddN-△k曲线的变化规律.研究结果表明,P-da/dN-△k曲线与应力比有很强的相关性,随着应力比增强,裂纹扩展速率增加.当可靠度要求增加时,这种趋势更明显.根据研究结果,恰当地考虑40CrMnSiMoVA钢对于不同应力比的影响,便于进行概率断裂力学分析.

关键词: 断裂 , 40CrMnSiMOVA钢 , P-da/dN-△k曲线 , 应力比

KⅧ-TbLⅣ离子3s3p 3P1-3s2 1S0 的自旋禁戒跃迁

牟致栋 , 魏琦瑛

原子核物理评论 doi:10.3969/j.issn.1007-4627.2004.01.015

在对KⅧ-TbLⅣ离子3s3p 3P1能级结构的多组态相互作用理论HXR方法计算的基础上, 分析了各种效应对等电子序列离子能级结构的影响, 找出了能级沿等电子序列变化的规律性. 预测计算了K Ⅷ-Tb LⅣ离子3s3p 3P1的能级. 由此进一步计算了KⅧ-TbL Ⅳ离子自旋禁戒跃迁3s3p 3P1-3s2 1S0的谱线波长、振子强度和跃迁概率.

关键词: KⅧ-TbLⅣ离子 , 自旋禁戒跃迁 , 波长 , 振子强度和跃迁概率

La对Fe-P-N合金Snoek-Ke-K■ster峰的影响

戢景文 , 魏全金 , 张国福 , 赖祖涵 , 陈廷国

金属学报

研究了F? P—N合金加?对Snoek—Ke-Koster(SKK)峰的影响,发现与合金含La,P的原子浓度比(C_(La)/C_p)有关:对于C_(La)/C_p较大(例如4.56和2.6)的合金,La有明显增强SKK阻?效应:对于C_(La)/C_p=0.27的P过饱和合金,La对SKK峰无明显影响。

关键词: 内耗 , Snoek-Ke-Koster peak , Fe-P-La-N alloy

Phase relations and flux research for zinc oxide crystal growth in the ZnO-K(2)O-P(2)O(5) system

Journal of Alloys and Compounds

The subsolidus phase relations of the ternary system ZnO-K(2)O-P(2)O(5) were investigated by means of Xray diffraction (XRD). There are 7 binary compounds. 6 ternary compounds and 20 three-phase regions in this system. The phase diagram of the pseudo-binary system KZn(4)(PO(4))(3)-ZnO was also investigated by means of XRD and differential thermal analysis (DTA) methods. KZn(4)(PO(4))(3)-ZnO is a eutectic system with eutectic temperature about 952 degrees C and eutectic point at about 2 mol% ZnO. Only narrow composition range in the KZn(4)(PO(4))(3)-ZnO system is suitable for the growth of ZnO crystals. (C) 2008 Elsevier B.V. All rights reserved.

关键词: ZnO-K(2)O-P(2)O(5) system;ZnO semiconductor;Phase diagrams;X-ray;diffraction;single-crystals;potassium;zno;orthophosphates;monophosphate;equilibria;knowledge;(kpo3)x;na

Ga、K双掺杂P型Bi0.5Sb1.5Te3材料的制备及热电性能

段兴凯 , 胡孔刚 , 丁时锋 , 满达虎 , 张汪年 , 马明亮

稀有金属

采用真空熔炼和热压方法制备了Ga和K双掺杂Bi0.5Sb1.5Te3热电材料.XRD结果表明,Ga0.02Bi0.5Sb1.48-xKxTe3块体材料的XRD图谱与Bi0.5Sb1.5Te3的XRD图谱对应一致,但双掺杂样品的衍射峰略微向左偏移.热压块体材料中存在明显的(001)晶面择优取向.SEM形貌表明材料组织致密且有层状结构特征.Ga和K双掺杂可使Bi0.5Sb1.5Te3在室温附近的Seebeck系数有一定的提高,而双掺杂样品的电导率均得到了不同程度的提高,其中Ga0.02Bi0.5Sb1.42K0.06Te3样品的电导率得到较明显的改善.在300～500 K测量温度范围内,所有双掺杂样品的热导率高于Bi0.5Sb1.5Te3的热导率,在300 K附近双掺杂样品的ZT值得到提高,其中Ga0.02Bi0.5Sb1.42K0.06Te3样品在300 K时ZT值达到1.5.

关键词: 双掺杂 , 真空熔炼 , 热压 , 显微结构 , 热电性能