材料期刊网

EFFECTS OF HDDR PROCESS ON STRUCTURE AND MAGNETIC PROPERTIES OF Nd(Fe,Ti)_(12)N_δ PREPARED BY MECHANICAL ALLOYING

B.Z Cui , X. K. Sun , X.G. Zhao , W.Liu , Q.F. Xiao , T. Zhao , Z.D. Zhang andY.C.Sui(Institute of Metal Research , The Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

The effects of the hydrogenation-disproportionation-desorption-recombination (HDDR) process on the structure and the magnetic properties of the mechanical alloying (MA) prepared Nd8Fe84 Ti8 alloy and its nitride counterpart have been studied in detail. It has been found that Nd(Fe, Ti)12Hδ is formed in the temperature range from 300 to 550°℃. The disproportionation is ready to start at 550°℃ and is complete at 960°℃.The desorption and the recombination are almost synchronized. The phase of Nd(Fe,Ti)7 is formed at 750°℃ during the HDDR treatment. With increasing temperature of HDDR process, the metastable structure of TbCu7 type is gradually transformed into the structure of ThMn12 type. The intrinsic coercivity and the maximum magnetic energy product increase with increasing temperature of HDDR process.

关键词: Nd(Fe , null , null , null

Response to the Comment on 'Conjectures on exact solution of three-dimensional (3D) simple orthorhombic Ising lattices'

Philosophical Magazine

The error of Equation (15b) in my article [Z.D. Zhang, Phil. Mag. 87 (2007) p.5309] in the application of the Jordan-Wigner transformation does not affect the validity of the putative exact solution, since the solution is not derived directly from that equation. Other objections of Perk's comment [J.H.H. Perk, Phil. Mag. 89 (2009) p.761] are the same as those in Wu et al.'s comments [F.Y. Wu et al., Phil. Mag. 88 (2008) p.3093; p.3103], which do not stand on solid ground and which I have sought to refute in my previous response [Z.D. Zhang, Phil. Mag. 88 (2008) p.3097]. The conjectured solution can be utilized to understand critical phenomena in various systems, whereas the conjectures are open to rigorous proof.

关键词: 3D Ising model;exact solution;conjecture;critical phenomena;ferromagnetism;magnetic phase transition;model;analyticity

PIP工艺制备2D C/SiC复合材料Z-向穿刺工艺

王其坤 , 胡海峰 , 陈朝辉 , 张玉娣 , 罗征

稀有金属材料与工程

针对2D C/SiC复合材料存在碳布层间缺乏纤维增强,层间结合较差的问题,提出通过Z-向穿刺工艺提高碳布层间结合,克服材料使用时可靠性不高的问题,并比较了穿刺工艺对复合材料微观结构和力学性能的影响.结果表明,通过Z-向穿刺工艺制得试样2D C/SiC-Z_(pin)的弯曲强度、弯曲模量和剪切强度分别为247.8 MPa、37.8 GPa和32.1 MPa,而未穿刺试样2D C/SiC的弯曲强度、弯曲模量和剪切强度分别只有219.3 MPa、34.4 GPa和23.3 MPa,由此可见,采用Z-向穿刺工艺能明显提高复合材料的力学性能.微观结构分析认为,试样力学性能提高的根本原因在于采用Z-向穿刺纤维加强了碳布层间结合,使材料具有较好的整体性,克服了复合材料层间结合较弱对力学性能带来的不利影响.

关键词: 2D , C/SiC , Z-向穿刺 , 微观结构 , 力学性能

2D-C/SiC复合材料低温动态Z向压缩性能

叶龙海 , 邓琼 , 汤忠斌

复合材料学报

采用Hopkinson压杆试验装置,对2D-C/SiC复合材料进行了低温条件下的Z向动态压缩性能试验研究,低温条件通过控制酒精和液氮的配比系数得到,通过改变波形整形器几何尺寸的方法来实现恒应变率加载,以得到准确、可信的试验结果.试验结果表明:由于复合材料内部含有大量初始微缺陷,2D-C/SiC复合材料在低温动态加载条件下呈现伪塑性行为,其破坏时并未表现出典型的脆性破坏,而是在应力达到压缩强度时出现了显著的应变软化现象,在经历了较大的变形后才最终破坏.随着温度的降低,复合材料的动态Z向压缩强度增加,但失效应变减小.2D-C/SiC复合材料在低温环境下,其内部纤维和基体之间界面结合力增强,同时强的界面结合力可以导致高的压缩强度.

关键词: 陶瓷基复合材料 , Hopkinson压杆试验装置 , 低温 , 动态Z向压缩力学性能 , 界面强度

Three-dimensional (3D) Ising universality in magnets and critical indices at fluid-fluid phase transition

Phase Transitions

Experimental data for critical exponents in some magnetic materials are compared with recent theoretical results on the three-dimensional (3D) Ising model, as derived by one of us (ZDZ) based on two conjectures [Z.D. Zhang, Conjectures on the exact solution of three-dimensional (3D) simple orthorhombic Ising lattices, Phil. Mag. 87 (2007), pp. 5309-5419]. It is found that critical exponents in some bulk magnetic materials indeed form a 3D Ising universality. Our attention is then focused on the critical indices at fluid-fluid phase transition. We suggest to use Zhang's exponent = 3/8 to fit the experimental data over the wider asymptotic region near the critical point of a fluid-fluid phase transition. The 3D Ising universality should exist for critical indices in a certain class of magnets and at fluid-fluid phase transition.

关键词: magnetically ordered materials;fluid-fluid;phase transitions;order-disorder effects;ferromagnetic curie temperature;liquid critical phenomena;x-ray-scattering;critical exponents;critical-point;coexistence;curves;binary-solutions;ionic-solutions;behavior;equation

First-principle investigation of 3d transition metal elements in gamma '-Co(3)(Al, W)

Journal of Applied Physics

The alloying effect of 3d transition metal elements on the lattice constants and their site preferences in gamma'-Co(3)(Al, W) are systematically studied based on a supercell model. The lattice constant of the gamma' phase is modified by the addition of 3d transition metal elements, and it increases in the order of Fe < Ni < Mn < Cr < V < Ti. Four types of site preference are identified for these 3d elements in gamma' phase by analyzing the binding energy and the impurity formation energy. Ni, Fe, V, and Ti are recognized to stabilize the gamma' phase. Their distinct alloying effect is further revealed by investigating the impurity-induced charge density difference and the partial density of states. These results are in agreement with the experimental data ever reported. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3319650]

关键词: augmented-wave method;co-base superalloy;electronic-structure;site;preference;ni3al;phase;temperature;stability;magnetism;alloys

MICROSTRUCTURE AND PROPERTIES OF SiC_w/6061Al COMPOSITE The Author is now with Institute of Metal Research,Academia Sinica,China

MA Zongyi YAO Zhongkai Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure

关键词: composite , null , null , null

CRACK GROWTH RATE IN WELD METAL OF HOMEMADE OFFSHORE STRUCTURE STEEL 36Z

ZANG Qishan LIU Kang Institute of Metal Research , Academia Sinica , Shenyang , ChinaKE Wei ZHENG Yuli Institute of Corrosion and Protection of Metals , Academia Sinica , Shenyang , China

金属学报(英文版)

Investigation was carried out of the crack growth rate in weld metal and heat affected zone (HAZ)of offshore structural steels,homemade steel 36Z together with foreign steel A537 of similar strength grade by comparison,in artificial sea water undergone fatigue with different frequencies.The crack growth rate in weld metal and HAZ of steel 36Z fatigued at low fre- queney may be 3—5 and 4—10 times as high as that at high frequency respectivley.The crack growth rate for steel 36Z may fairly match that of A537,The crack growth model and frac- ture of weld metal in corrosive medium were also discussed.

关键词: weld metal , null , null , null , null

EFFECTS OF METAL IONS ON THE CONFORMATIONAL CHANGES OF DNA

G.Q. Liu , Y.Y. Meng , S.H. Liu , Y.H. Hu

金属学报(英文版)

DNA takes on multi-different conformations such as A-, B-, C-, D- and Z-form. These conformations can transit to one another when DNA deposited in some metal ions solutions or when changing the concentrations of the same metal ions. Here, several major conformational transitions of DNA induced by metal ions under different environment were introduced and the mechanism of the interaction of metal ions with DNA was discuss in detail.

关键词: DNA , null , null

Luoyang Institute of Refractories Research Ministry of Metallurgical Industry

ZHONG Xiangchong Luoyang Institute of Refractories Research , Luoyang , China.

材料科学技术（英）

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