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

Theoretical study of the superhyperfine parameters for Cu(2+) in K(2)PdX(4) (X = Cl, Br)

Hyperfine Interactions

The superhyperfine parameters T(j) (j = x, y, z) for Cu(2+) in the square-planar K(2)PdX(4) (X = Cl, Br) are theoretically studied from the perturbation formulas of these parameters for an octahedral 3d(9) cluster, by considering both the contributions from the crystal-field and charge-transfer mechanisms. The related molecular orbital coefficients are determined from the cluster approach in a uniform way. Based on one adjustable proportional factor rho for the orbital admixture coefficients, the calculated results of present work show reasonable agreement with the observed values.

关键词: Electron paramagnetic resonance (EPR);Superhyperfine interactions;Cu(2+);K(2)PdX(4) (X = Cl, Br);atomic screening constants;square-planar;angular distortions;liquid-membrane;scf functions;absorption;k2pdcl4;spectra;complexes;carrier

K60、X70管线钢奥氏体晶粒长大及再结晶的对比分析

孙震 , 张备

上海金属

通过金相观察的方法,研究了K60、X70管线钢在不同加热温度下奥氏体晶粒长大的规律及在不同变形量和变形温度下奥氏体晶粒再结晶的规律.结果表明:加热温度分别达到1 150℃和1 200℃时,K60、X70晶粒尺寸急剧增大;随着变形温度的提高,K60、X70奥氏体再结晶的临界变形量均降低;变形温度在1 150℃,变形量分别为50％和30％时,K60、X70再结晶程度可达90％以上.相比K60,X70未再结晶区狭小,为避免混晶的产生,轧制过程应尽量避开部分再结晶区.

关键词: 管线钢 , 再结晶 , 奥氏体晶粒 , 控制轧制

Investigations on the EPR Parameters for the Square Planar Cu(2+) Centers in K(2)PdX(4) (X = Cl, Br)

Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences

The EPR parameters g factors g(parallel to), g(perpendicular to) and the hyperfine structure constants A(parallel to) and A(perpendicular to) for the square planar Cu(2+) centers in K(2)PdX(4) (X = Cl, Br) are theoretically investigated from the perturbation formulas of these parameters for a 3d(9) ion under tetragonally elongated octahedra. In these formulas, not only the contributions from the conventional crystal-field (CF) mechanism, but also those from the charge-transfer (CT) mechanism are taken into account. The related molecular orbital coefficients are uniformly determined from the cluster approach, and the tetragonal field parameters Ds and Dt are obtained from the superposition model and the local structures of the systems. Based oil only one adjustable parameter, the present results are in reasonable agreement with the observed Values. Importance of the charge-transfer contributions is more significant for ligand Br than that for Cl due to the stronger covalency and much larger spin-orbit coupling coefficient of the former.

关键词: Crystal- and ligand fields;Electron paramagnetic resonance (EPR);Cu(2+);K(2)PdX(4) (X = Cl, Br);charge-transfer transitions;atomic screening constants;liquid-membrane;scf functions;crystal;complexes;spectra;resonance;cucl42;model

K60、X80管线钢连铸坯的高温塑性

张双平 , 刘靖 , 张艳 , 张备 , 韩静涛 , 彭杰

机械工程材料

采用Gleeble 1500型热模拟试验机研究了K60、X80管线钢连铸坯在1 350～650℃、1.0×10-3 s-1应变速率下拉伸时的高温塑性.结果表明:两种钢坯的第Ⅰ脆性区间为熔点～1 300℃;在高温区1 300～900℃时两种钢的塑性均很好,没有产生明显脆化;第Ⅲ脆性区间为900～700℃,该区域可分为γ单相区和γ+α两相区两部分.

关键词: 管线钢 , 高温塑性 , γ→α相变 , 动态再结晶

Bi2Sr2CaCu2Oy单晶的变温(77～300K)X射线衍射研究

胡林生 , 孙学峰 , 赵霞 , 李晓光

低温物理学报 doi:10.3969/j.issn.1000-3258.1999.02.009

我们进行了Bi2Sr2CaCu2Oy(Bi2212)单晶变温X射线衍射(XRD)研究,定量给出温度从77K变化至300K时,c轴晶格参数和0038主峰的半高宽(FWHM)Δθ的变化.实验发现,从77K至140K,晶格参数c值变化是线性的,随温度较慢地单调增大;从140K附近至300K,c值的变化偏离了原来的线性,随温度较快地单调增大.另外,0038主峰的半高宽Δθ随温度的变化在140K附近出现一个极大值.这表明Bi2212单晶在140K附近发生了明显的反常结构变化.

关键词:

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature

La_（0.60）Sr_（0.40-x）K_xMnO_3系列材料的磁电阻效应

赵福伟 , 唐贵德

材料科学与工程学报

利用溶胶-凝胶法（sol-gel）制备了多晶类钙钛矿型稀土锰氧化物La0.60Sr0.40-xKxMnO3（x=0.00,0.15,0.20,0.30）。发现K＋取代部分Sr2＋后,可使样品的居里温度降至室温附近,并且使样品的室温磁电阻比替代前明显增大。在1.8T的磁场下,x=0.30的样品磁电阻峰值为21%,相应的峰值温度为304K。而母体La0.60Sr0.40MnO3的磁电阻峰值仅为6.4%,峰值温度为373K。可见K＋离子替代使室温附近样品的庞磁电阻效应有了明显的改善。

关键词: 钙钛矿锰氧化物 , 磁电阻 , 溶胶-凝胶法

X70管线钢J1d和K1a与V型缺口Ak关系研究

朱杰武 , 柳永宁 , 许雁 , 冯耀荣

机械工程材料 doi:10.3969/j.issn.1000-3738.2005.06.007

在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.

关键词: 管线钢 , 断裂韧度 , 止裂韧度 , 韧-脆断裂转变

Investigations of EPR g Factors and Rhombic Distortion for the Rhombic Cu2+ Centers in K2Zn1-x Cu (x) F-4 Crystals at Low Temperature

Applied Magnetic Resonance

The electron paramagnetic resonance g factors g (i) (i = x, y, z) of two rhombic Cu2+ centers, Cu2+(II) and Cu2+(III), in K2Zn1-x Cu (x) F-4 crystals found at low temperature are calculated from the complete diagonalization (of energy matrix) method based on the cluster approach. The calculations show that the ground state wave function of the two rhombically compressed Cu2+ centers is with a small admixture of . The rhombic distortions for both Cu2+ centers are obtained from the calculations. The results are discussed.

关键词: electron-paramagnetic-resonance;atomic screening constants;hyperfine;parameters;gyromagnetic factor;spin resonance;scf functions;field;copper(ii);dependence;spectra