Si-Young Kwak
,
Jae-Wook Baek
,
Jeong-Ho Nam
,
Jeong-Kil Choi
材料科学技术（英）
It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.
关键词:
Casting process
,
null
,
null
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
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
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
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
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
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
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
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
