材料期刊网

DESIGN AND PREPARATION OF SILICON NITRIDE COMPOSITE WITH HIGH FRACTURE TOUGHNESS AND NACRE STRUCTURE

Y Huang , H.N Hao , Y.L. Chen and B.L.Zhou (1)Department of Materials Science and Engineering , Tsinghua University , Beijing 100084 , China 2)Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China Manuscript received 26 August 1996)

金属学报(英文版)

A new way of designing and preparing silicon nitride ceramic composite with high fracture toughness and nacre structure has been proposed. To mimic the laminated structure of nacre, Si_3N_4 matrix ceramic layer can be obtained through compacting rolling method. To mimic the secondary toughening of nacre structure, SiC whisker is added into Si_3N_4 and acts as the secondary toughening phase. Boron nitride (BN)is selected to mimic the organic layer in nacre so as to form the weak interfaces between Si_3N_4 layers. Alumina is added into BN to adjust the bonding strength of the interface.The Si_3N_4 sheets are stacked into the die after coating with BN. After the removal of the organic matter in them, the green body is hot pressed at 1820℃for 1.5 hours under N_2 atmosphere. The fracture toughness of the so-made Si_3N_4 composite at room temperature is 20.36MPa m~(1/2), the three-point bending strength at room temperature is 651.47MPa. The crack spreads and deflects along the interface between BN and Si_3N_4 layer and extends through the BN layer into Si_3N_4 layer. The improvement of the fracture toughness may be due to the staircase-shape-like crack which provides the long crack path, the fracture and deformation of Si_3N_4 layer, and the pullout of SiC whiskers from the Si_3N_4 layer.

关键词: :secondary toughening , null , null , null

ELECTRONIC STRUCTURE OF Pd-Y-Si GLASSES

LUO Meiqing CHEN Nianyi Shanghai Institute of Metallurgy , Academia Sinica , Shanghai , ChinaYU Zhizhong Shanghai Institute of Testing Technics , Shanghai , ChianNING Yuantao ZHOU Xinming Kunming Institute of Precious Metals , Kunming , China CHEN Nianyi , Professor , Shanghai Institute of Metallurgy , Academia Sinica , Shanghai 200050 , China

金属学报(英文版)

The electronic structure of Pd-Y-Si glass has been investigated by ESCA and quantum chem- ical calculation.It was found that the valence electrons of Y transferred to Si atoms in this metallic glass,forming polar covalent bonds.Perhaps these strong covalent bonds link Si and Y atoms to form clusters that hinder the process of crystallization.

关键词: Pd-Y-Si glass , null , null , null

SOLUBILITIES OF Ce,Nd AND Y IN α-Fe

LI Laifeng XING Zhongshu Institute of Metal Research , Academia Sinica , Shenyang , China XING Zhongshu , professor , Institute of Metal Research , Academia Sinica , Shenyang 110015 , China

金属学报(英文版)

The solubilities of Ce,Nd and Y in α-Fe at 873 to 1153 K have been deter mined by means of electron microprobe quantitative analyses.The temperature dependences of the solubilities were obtained from the experimental data.The results have been compared with those deter- mined by three other technigues,very good agreement was obtained between the results of all these techniques.

关键词: α-Fe , null , null , null , null

沸石Y用于组装纳米CdS

翟庆洲 , 蔡建岩 , 于淼

稀有金属材料与工程

以沸石Y及以甲基三甲氧基硅烷对沸石Y进行表面改性后的Y(m)沸石作主体,用离子交换法制备Cd-Y及Cd-Y(m)样品,然后以硫代乙酰胺取代有毒的硫化氢作硫源,水热法制备Y-CdS及Y(m)-CdS主-客体纳米复合材料.利用粉末XRD、化学分析、红外光谱、固体扩散漫反射吸收光谱、发光研究对制备的样品进行了表征.化学分析表明,CdS已进入沸石Y(Ym)主体中;XRD结果表明,CdS进入沸石Y(Ym)后,制得的复合材料沸石骨架仍然存在,且保持高度有序性,不改变骨架的长程有序性;红外光谱结果表明,在所制备的Y-CdS及Y(m)-CdS样品中,有Si-O-Cd新键生成;固体扩散漫反射吸收光谱结果表明,沸石Y和Y(m)对可见光基本无吸收,Y-CdS和Y(m)-CdS吸收无明显差别;组装CdS后,Y-CdS及Y(m)-CdS产生发光现象.所制得的Y-CdS及Y(m)-CdS主-客体纳米复合材料具有作为发光材料的潜在性.

关键词: Y沸石 , Y改性沸石 , 甲基三甲氧基硅烷 , 纳米CdS , 主-客体纳米复合材料 , 表征

Microstructure Formation and Mechanical Property Involving Icosahedral Quasicrystal Phase of Y Rich Mg-Zn-Y Quasicrystal Alloy

D.Q. Wan , G.C. Yang

金属学报(英文版)

The microstructure formation and mechanical property involving icosahedral quasicrystal (I-phase) in the Y-rich Mg-Zn-Y alloy have been studied. The equilibrium formation of I-phase from the Y-rich Mg-Zn-Y melt is through a peritectic reaction between the Y-rich melt and the primary W-phase, which is discussed in detail. The independent nucleation and coupling growth mechanism between the W-phase and the I-phase, from the melt, are revealed, which is significant for understanding the peritectic reaction process involving icosahedral quasicrystal in the Mg-Zn-Y alloy. The mechanism of the quasicrystal phase strengthened magnesium alloys is also discussed here.

关键词: Mg-Zn-Y , null , null

EFFECT OF Y ON MECHANICAL PROPERTIES OF Fe-20Cr-4Al-Y ALLOY

LI Bei WU Shuangxia MENG Guang'en JIANG Liping PANG Wenjie Baotou Research Institute of Rare Earth , Baotou , China Baotou Research Institute of Rare Earth , P.O.Box 131 , Baotou 014010 , China

金属学报(英文版)

With the increase of Y content in the Fe-20Cr-4AI-Y alloy,the uniform deformability of tensile specimens was found to be slightly decreased,as well as,the fracture strength and re- duction after necking remarkably dropped.This seems to be dependent upon the brittle phase containing Y.The behaviour of Y-containing phase may be improved by adjusting the metallurgical technological process.

关键词: Fe-Cr-A1 alloy , null , null

THE　EFFECTS　OF　Y,Zr　AND　Si　ADDITIONS　ONCYCLICOXIDATIONBEHAVIOUROFFeAlINTERMETALLICS

腐蚀学报（英文）

研究了Y、Zr、Si对FeAl金属间化合物在1000～1200℃下循环氧化性能的影响,并用X射线衍射、扫描电镜及能谱分析等手段分析了氧化产物。结果表明,Y、Zr、Si的加入大大提高了FeAl金属间化合物表面氧化膜的抗剥落能力。从氧化动力学上看,Y和Zr或Y和Si的同时加入比单独加Zr效果好。

关键词: FeAl金属间化合物 , null , null

Au-Ag-Y三元系富Au-Ag区域(Y≤34at%)的700℃等温截面

张康侯 , 陈亮维 , 尹俊美 , 陈藜莉 , 谢明 , 符世继

贵金属 doi:10.3969/j.issn.1004-0676.2008.04.001

在Au-Ag、Au-Y和Ag-Y二元合金相图的基础上,采用X-射线衍射分析、电子探针等手段研究了Au-Ag-Y三元系中富金-银区域(Y≤34at%)的700℃等温截面.发现:在该截面的富金银侧沿着Au-Ag二元匀晶系存在一个单相区Au(Ag)或Ag(Au);在二元金属间化合物Au2Y和Ag2Y之间存在一个无限固溶体区域(Au2Y)或(Ag2Y).在该部分700℃等温截面上一共有6个单相区:Au(Ag) 或 Ag(Au)、Au6Y、Au51Y14、α(Au2Y) 或 (Ag2Y)、 Au3Y和 Ag51Y14;9个两相区:Au(Ag)+ Au6Y、 Au(Ag)+ Au51Y14、 Au(Ag)+ Au3Y、 Au(Ag)+ α(Au2Y)、 Au(Ag)+ Ag51Y14、Ag51Y14+α(Au2Y)、α(Au2Y)+ Au3Y、 Au3Y+ Au51Y14 和 Au51Y14+ Au6Y;4个三相区: Ag51Y14+α(Au2Y)+Au(Ag)、α(Au2Y)+ Au3Y+ Au(Ag)、 Au3Y+ Au51Y14+ Au(Ag) 和 Au51Y14+ Au6Y+ Au(Ag).在Au-Ag-Y三元系的该成分区域没有发现新的三元中间相.

关键词: 材料科学基础学科 , Au-Ag-Y三元系 , 合金 , 相图 , 等温截面

Multiferroic phase diagram of Y partially substituted Dy(1-x)Y(x)MnO(3)

Applied Physics Letters

The effect of nonmagnetic Y partial substitution at the Dy site in Dy(1-x)Y(x)MnO(3) up to x=0.2 on magnetism, specific heat, and ferroelectricity is investigated, which resulted in a preliminary multiferroic phase diagram. It is revealed that the Y partial substitution suppresses the Dy-spin ordering point (T(Dy)) and ferroelectric ordering point (T(FE)) but enhances the Mn-spin ordering point (T(N)). The interaction between the spins of Dy and Mn is remarkably affected by Y substitution. The measured electrical polarization depends on the Y substitution in a complex way because the ferroelectricity is sensitive to the interaction between the spins of Dy and Mn. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3536506]

关键词: ferroelectricity;polarization

Ni液中Y-S平衡的研究

王龙妹 , 杜挺

金属学报

用直接平衡法研究了1500,1550,1600℃Ni液中Y-S平衡关系,测定了钇的脱硫常数lgK_(YS)及Y,S的一阶活度相互作用系数e_S~Y与温度的关系,并进行了有关的热力学计算。由测得的数据算出Ni液中YS的标准生成自由能△G_((Y)S),钇的标准溶解自由能△G_((Y)(l)→[Y]Ni),活度系数γ_Y~o,以及钇的克原子分数自相互作用系数∑_Y~Y和百分浓度自相互作用系数e_Y~Y与温度的关系。 对于反应[Y]_(Ni)+[S]_(Ni)=YS_(s) △G_((Y)S)=-215000+95.53T(cal/mol)脱硫常数: lgK_(YS)=-47000/T+20.86 e_S~Y=-350200/T+179 △G_((Y)(l)→[Y]Ni)=126200-79.31T(cal/mol) lgγ_(Y)=27584/T-15.151 ∑_Y~Y=-127T05/T+69.79 e_Y~Y=-364.8/T+0.2018

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