材料期刊网，材料期刊，材料类期刊，材料期刊投稿

在连铸过程中,结晶器保护渣在通过控制润滑来实现较好的可浇性和铸坯质量方面起到重要作用.在缺乏结晶器保护渣不同热物性的情况下,黏度是判断结晶器保护渣润滑性能的必要参数.许多研究人员(包括笔者)证实了熔融的结晶器保护渣的流变性能.实际操作中,在剪切速度约为10～40 s-1的结晶器上表面,为减少卷渣,需要高黏度保护渣;但是在剪切速度为100～1 000 s-1的结晶器壁,为了保证最大的润滑性能,保护渣黏度应该低.因此,这个特定的属性可能有利于实际连铸过程.目前的研究试图通过用旋转黏度计测量CaO-CaF2-SiO2、CaO-CaF2-B2O3-SiO2和CaO-CaF2-SiO2-Si3N4基保护渣体系的黏度来表征该体系的黏弹性(名为流变性能).旋转黏度计配备一个1 623 K温度下受控氧逸度的熔炉.而且,通过拉曼光谱和XPS分析来了解结晶器保护渣黏弹性和结构之间的关系.根据结果,所有经检测的结晶器保护渣都具有流变性能,当剪切速率增大时,黏度降低.应用Os-wald-De Waele指数模型来定量每个结晶器保护渣的剪切变稀度,得出每个结晶器保护渣的聚合度与剪切变稀行为的强度大体上成比正.

关键词: 结晶器保护渣 , 非牛顿流体 , 剪切变稀 , 碱度 , 聚合度

AN INVESTIGATION OF THE HO-NI PHASE-DIAGRAM

Journal of Alloys and Compounds

The phase diagram of the Ho-Ni binary system was investigated by X-ray diffraction, differential thermal analysis, optical microscopy and electron probe microanalysis techniques. The existence of eight intermediate phases has been confirmed: Ho3Ni, Ho3Ni2, HoNi, HoNi2, HoNi3, HO2Ni7, HoNi5, and Ho2Ni17. The homogeneity region of the HoNi2 phase extends from 65.6 to 66.7 at.% Ni. The other phases are line compounds. No appreciable solid solubility of holmium in nickel or of nickel in holmium was observed. Ho3Ni2 exists in two structural modifications depending on the temperature. HoNi and HoNi5 melt congruently at 1060 and 1370-degrees-C respectively. There are seven peritectic reactions and three eutectic reactions in this system.

关键词: intermetallic compounds

Cr,Tm,Ho∶YAG中Tm→Ho的能量转移

王燕 , 常勇 , 殷绍唐 , 王晓光 , 曹余惠

人工晶体学报 doi:10.3969/j.issn.1000-985X.2002.04.014

本文采用Boltzmann分布近似,计算了不同温度下Tm→Ho的净能量转移;计算了实验中不同温度下Ho3+离子的荧光发射强度在整个Tm-Ho体系荧光发射中的比例.我们的实验和计算表明,对Tm-Ho准三能级体系采用Boltzmann分布近似,其计算结果是可信的.

关键词: Cr,Tm,Ho∶YAG晶体 , Boltzmann分布近似 , 能量转移效率

Effect of Ho on the microstructure and compressive properties of NiAl-based eutectic alloy

Materials Letters

The effect of various holmium content on the microstructure and compressive behavior of NiAl-28Cr-6Mo-0.15Hf eutectic alloy has been investigated by using combination of SEM, TEM and compression test. The results suggest that appropriate Ho addition improves the compressive ductility at room temperature and the high temperature strength at 1273 K of the alloy significantly. In addition, lamellar microstructure inside of eutectic cell and eutectic cell get refinement gradually, but the intercellular region become coarse, with increase of Ho content. Furthermore, Ni2Al3Ho phase, with hexagonal cristal structure, is observed in the alloy. (C) 2008 Elsevier B.V. All rights reserved.

关键词: NiAl-based alloy;microstructure;mechanical properties;mechanical-properties;composites;toughness;cr

激光晶体Zn:Ho:LiNbO3的生长及其光学性能

赵业权 , 徐悟生 , 徐衍岭 , 杨春晖 , 徐玉恒

人工晶体学报 doi:10.3969/j.issn.1000-985X.1998.01.011

在生长LiNbO3晶体过程中掺进ZnO和Ho2O3,生长出Zn:Ho:LiNbO3晶体.测试了Zn:Ho:LiNbO3晶体的双折射梯度、光损伤阈值、吸收光谱和荧光光谱.研究表明,Zn:Ho:LiNbO3晶体是优良的激光介质材料.

关键词: Zn:Ho:LiNbO3晶体 , 光损伤阈值 , 荧光光谱 , 吸收光谱 , 引上法晶体生长 , 激光晶体

Magnetic properties of Ho2Co17-xGax compounds

Journal of Alloys and Compounds

We have studied the magnetic properties of Ho2Co17-xGax compounds (x less than or equal to 7) by means of magnetic measurements and X-ray diffraction on magnetically aligned powders. The Curie temperature and the spontaneous moment decrease strongly with increasing Ga concentration. The compounds that are magnetically ordered at roam temperature have an easy magnetisation direction at room temperature which is perpendicular to the c-direction. (C) 1998 Elsevier Science S.A.

关键词: rare earth compounds;Co rich compounds;magnetic properties

Yb,Ho:YAG晶体的生长及光谱性能

成诗恕 , 程艳 , 赵呈春 , 李东振 , 徐晓东 , 徐军

人工晶体学报

采用中频感应提拉法成功生长出Yb (15 at%),Ho (1 at%):YAG激光晶体,研究了室温下晶体的吸收光谱,发射光谱特性和荧光寿命.吸收光谱中在938 nm处存在Yb3+的吸收带,能与InGaAs 激光二极管(LD)有效耦合,适合激光管二极抽运.荧光光谱中存在两个荧光主峰,分别位于1907 nm和2091 nm附近.研究表明:Yb,Ho:YAG晶体是一种有发展前景的激光增益介质.

关键词: Yb,Ho:YAG晶体 , 提拉法 , 晶体生长 , 光谱特性

Magnetocaloric effect in Ho(2)In over a wide temperature range

Applied Physics Letters

The compound Ho(2)In exhibits two successive magnetic phase transitions: a spin-reorientation transition at T(SR)=32 K and a magnetic-ordering transition at T(C)=85 K. The maximum reversible -Delta S(M) values are 6.3 and 11.2 J/kg K at T(SR) and T(C), respectively, for a field change of 5 T. These two -Delta S(M) peaks with the same sign are partly overlapping, which results in a wide temperature interval with appreciable magnetocaloric effect. The results on Ho(2)In indicate that materials with successive SR and magnetic-ordering transitions may constitute an important new class of magnetic refrigerants since they work in a wider temperature range than the conventional refrigerant materials.

关键词: holmium alloys;indium alloys;magnetic cooling;magnetic moments;magnetic transitions;magnetic refrigeration;diffraction;capacity;heat

Enhanced ferroelectricity in orthorhombic manganites Gd(1-x)Ho(x)MnO(3)

Journal of Applied Physics

A series of orthorhombic manganites Gd(1-x)Ho(x)MnO(3) (0 <= x <= 0.5) are synthesized. The Ho doping leads to a transition of paraelectric phase into ferroelectric one, making Gd(1-x)Ho(x)MnO(3) multiferroic. It is argued that the enhanced electric polarization originates from the transition of the A-type Mn(3+) anti-ferromagnetic state into the spiral spin order driven by the reduction of Mn-O-Mn bond angle due to the doping. The noncollinear spin order of the A-site Ho(3+) spins at high doping level may also make contribution to the polarization. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3535543]

关键词: polarization;perovskite