材料期刊网

MICROSTRUCTURE AND COMPRESSIVE PROPERTIES OF REACTION-MILLED NiAl-10wt%TiC COMPOSITE

L.Z ZHOU and J.T. GUO(Dept. of Superalloy and Special Casting , Institute of Metal Research , The Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

A NiAl- TiC composite with fine grains was prepared by mechanical alloying elemental powders and hot pressing in vacuum. The TiC particles with diameters of about 50-100nm preferentially distribute on grain boundaries and those with a mean size less than 10nm disperse uniformly throughout the grains. Compressive properties of the composite at room temperature show significantly improved ductility and strength over that of cast NiAl, and its high temperature strength is 3 to 4 times as large as that of cast NiAl.

关键词: intermetallics , null , null , null

Effect of Casting Modulus on Microstructure and Segregation in K441 Superalloy Casting

Weiguo Jiang

材料科学技术（英文）

Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy (OM) and scanning electron microscopy (SEM). The micro-segregation was tested by energy dispersive spectroscopy (EDS) and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.16 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of Al increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of Al and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.

关键词: Superalloy

Effect of Casting Modulus on Microstructure and Segregation in K441 Superalloy Casting

材料科学技术（英文）

Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy (OM) and scanning electron microscopy (SEM). The micro-segregation was tested by energy dispersive spectroscopy (EDS) and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.16 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of Al increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of Al and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.

关键词: Superalloy;Turbine blade;Casting modulus;Microstructure;Segregation;grain-boundary segregation;single-crystal superalloy;ni-base;superalloy;cooling rate;behaviors

扩展的t-J模型中的非公度反铁磁自旋关联

马天星 , 梁颖 , 冯世平

低温物理学报 doi:10.3969/j.issn.1000-3258.2003.z1.032

在t-J模型和fermion-spin理论框架下,研究了电子次近邻跃迁t′对欠掺杂四方晶格铜氧化物材料的反铁磁非公度自旋关联的影响.结果表明,虽然电子次近邻跃迁项使得自旋结构因子的非公度峰强度增加,但对物理上合理的、较小的t′值,t-t′-J模型的非公度自旋关联与t-J模型定性一致.

关键词:

M40J和T300碳纤维的微结构

孙银洁 , 胡胜泊 , 李秀涛

宇航材料工艺 doi:10.3969/j.issn.1007-2330.2010.02.027

利用SEM、TEM、XPS、XRD、Raman和元素分析仪分析了M40J和T300的表面化学、物理及微观结构特征.研究发现:M40J含碳量高于T300纤维,而含氮量低于T300纤维,且表面活性基团比T300纤维低;M40J和T300碳纤维表面具有大量沟槽,前者相对长而浅,后者相对短而深;T300纤维端面皮芯结构明显,而M40J端面结构较均匀;M40J的微晶结构及取向性优于T300碳纤维.

关键词: M40J碳纤维 , 微观结构 , 化学特征 , 物理特征

T型接头蒙皮厚度对Z-pin增强效果的影响

李梦佳 , 陈普会 , 孔斌 , 彭涛 , 姚正兰 , 邱学仕

复合材料学报 doi:10.13801/j.cnki.fhclxb.20150930.002

在关于拉脱载荷下Z-pin增强T型接头的有限元模拟方法基础上,通过对2组蒙皮厚度分别为7.2 mm和4.0 mm的试验件的试验结果进行分析,研究了T型接头蒙皮厚度对 Z-pin增强效果的影响。结果表明：Z-pin增强效果随着蒙皮厚度的减小而增大。蒙皮厚度大于5 mm,Z-pin不能提高结构的最大承载能力,但可显著提高结构首次掉载后的承载性能,使T型接头在较大的加载位移下仍保持较高的承载能力；无论蒙皮厚薄,结构首次掉载后,各Z-pin增强T型接头可达到的载荷平台是相当的,且该载荷平台随蒙皮的变厚有降低的趋势。

关键词: 复合材料 , T型接头 , Z-pin , 蒙皮厚度 , 有限元模拟

t-t′-J-U模型中电子次近邻跃迁对Gossamer超导的影响

谢兰清 , 王彩霞

兵器材料科学与工程

基于重整化平均场理论,在二维空穴掺杂t-t′-J-U模型的框架下,用Gutzwiller平均场近似理论研究高温超导体的基态相图,分析了次近邻跃迁电子(t′)对电子平均双重占据数(d)的影响.发现在掺杂浓度δ≠0的掺杂Gossamer超导态,次近邻跃迁的引入使d的数值在欠掺杂浓度区增大,在过掺杂浓度区显著减少.

关键词: 高温超导体 , 相图 , 电子态 , 电子次近邻跃迁 , 双重占据

Z-pin参数对复合材料T型接头拉脱承载能力的影响

李梦佳 , 陈普会 , 孔斌 , 彭涛 , 姚正兰 , 邱学仕

复合材料学报 doi:10.13801/j.cnki.fhclxb.201502.002

利用二维平面应变模型对Z-pin增强T型接头试样进行失效分析,采用内聚力模型模拟界面的破坏情况,通过在分层的上下界面加入非线性弹簧元模拟Z-pin的增强作用,非线性弹簧元的力学性能(桥联律)由细观力学方法获得,数值结果与试验值吻合较好.在已验证有限元方法的基础上,研究了Z-pin直径、密度及植入角度等对T型接头拉脱承载能力的影响.结果表明:Z-pin增强可显著提高T型接头的拉脱承载能力,与未Z-pin增强的T型接头相比,Z-pin增强明显延缓了掉载;T型接头的拉脱承载能力随Z-pin直径和密度的增加而增大,随植入角度的增大而减小;在所研究的角度范围内,当植入角度为60°时,T型接头的拉脱承载能力最好;Z-pin直径和密度对拉脱承载能力的影响远比植入角度的影响显著.

关键词: 复合材料 , T型接头 , Z-pin , 非线性弹簧 , 桥联律

z-pin增强复合材料T型接头层间性能的建模与分析

李成虎 , 燕瑛

复合材料学报

提出了基于z-pin桥联力试验的z-pin增强复合材料T型接头层间性能的模拟方法.每根z-pin的作用有两部分:增加了分层的张开阻力与剪切阻力.在有限元模拟中通过在相应的节点上加两个方向(竖直方向和水平方向)的非线性弹簧模拟张开阻力和剪切阻力.通过张开型z-pin桥联力试验和剪切型z-pin桥联力试验得到两条力-位移曲线,再把曲线各自赋予到所有竖直非线性弹簧和水平非线性弹簧,从而模拟z-pin对复合材料T型接头层间性能的增强效果.在T型接头拉拔试验模拟分析中,研究了不同跨距和不同z-pin间距对拉拔力的影响.模拟分析表明跨距对拉脱位移影响较大,z-pin间距对最大拉拔力影响较大.

关键词: z-pin , 复合材料 , z-pin桥联力 , 张开型 , 剪切型 , 非线性弹簧

快速凝固Al-Li-Cu-Mg-Zr合金中Z相和T相的结构关系

张立春 , 何安强 , 吴玉琨 , 叶恒强 , 张永昌

金属学报

利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成

关键词: Al-Li-Cu-Mg-Zr合金 , Z hexagonal phase , T f.c.c. phase , shear structure