J. T. Niu
,
H. T. Li
,
X. D. Meng and P. Karjaleinen 1) Analysis and Measurement Center
,
Harbin Institute of Technology
,
Harbin 150001
,
China 2) Department of Mechanocal Engineering
,
The University of Oulu
,
Finland
金属学报(英文版)
With the development of modern science and technology, especially computer science, the numerical simulation method has been widely used in material hot-working. Mary achievements have been made in this field by using the numerical simulation method. The numerical simulation method, especially finite element method fully described in this paper.Applications of the numerical simulation method in material hot-working are also discussed. Finally, the future of the numerical simulation method is outlined.
关键词:
numerical simulation
,
null
,
null
J. T. Niu
,
Y. H. Tian
,
B. Y. Li
,
J. J. Xu
,
L.M. Liu (National Key Laboratory of Advanced welding Production Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
Tensile strength of diffusion welded joint of aluminum matrix composite is very low due to its poor weld- ability.In this paper, solution and age treatments were conducted on the welded joint of Al2O3p/ 6061Al composite subjected to diffusion welding using Gleeble 1500 machine, and ensile strength and microstructure of welded joint aged at175℃ were measured and analyzed respectively, Results showed that aging precipitation of welded joint is promoted effectively because of redistribution of reinforcement and a few number of dislocations in the matrix of weld zone resulting from welding pressure,and hence tensile strength of welded joint is increased significantly after aging treatment.
关键词:
aluminum matrix composite
,
null
,
null
J. T. Niu
,
L. M. Liu
,
J. P. Zhai
,
J. Yu
,
X. M. Zhang (National Key Laboratory of Advanced Welding Production Technology
,
HIT
,
Harbin 750001
,
China)
金属学报(英文版)
Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for the loss of joint strength was analyzed.It was pointed out that the key processing parameters affecting the strength of joint was the welding temperature.The high quality joint can be successfully obtained with appropriate diffusion welding parameters.
关键词:
particle reinforced aluminium matrix composite
,
null
,
null
孙银洁
,
胡胜泊
,
李秀涛
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2010.02.027
利用SEM、TEM、XPS、XRD、Raman和元素分析仪分析了M40J和T300的表面化学、物理及微观结构特征.研究发现:M40J含碳量高于T300纤维,而含氮量低于T300纤维,且表面活性基团比T300纤维低;M40J和T300碳纤维表面具有大量沟槽,前者相对长而浅,后者相对短而深;T300纤维端面皮芯结构明显,而M40J端面结构较均匀;M40J的微晶结构及取向性优于T300碳纤维.
关键词:
M40J碳纤维
,
微观结构
,
化学特征
,
物理特征
谢兰清
,
王彩霞
兵器材料科学与工程
基于重整化平均场理论,在二维空穴掺杂t-t′-J-U模型的框架下,用Gutzwiller平均场近似理论研究高温超导体的基态相图,分析了次近邻跃迁电子(t′)对电子平均双重占据数(d)的影响.发现在掺杂浓度δ≠0的掺杂Gossamer超导态,次近邻跃迁的引入使d的数值在欠掺杂浓度区增大,在过掺杂浓度区显著减少.
关键词:
高温超导体
,
相图
,
电子态
,
电子次近邻跃迁
,
双重占据
王昂
,
公茂琼
,
吴剑峰
工程热物理学报
微微型节流制冷器在微小元件和制冷应用中有广阔的前景.本文通过对搭建一微型压缩机驱动的微型混合工质节流制冷器系统,取得初步结果.该微微型J-T节流制冷器采用3D打印技术,通道特征尺寸为0.1 mm,突破了传统机械加工的极限.通道深宽比达到8:1.初步实验表明,微微型J-T节流制冷器达到了230 K温区.由于采用微型压缩机驱动,系统结构紧凑,可在便携生物储存设备、低温医疗以及电子器件冷却等领域应用并能长期运行.
关键词:
微微型节流制冷器
,
混合工质
,
3D打印
Communications in Theoretical Physics
By using strong-field scheme, the complete d(5) energy matrix with D-2d symmetry has been constructed. Then, by diagonalization of this matrix at normal and various pressures, the whole energy spectrum [including the ground-state zero-field splitting (GSZFS)] and its pressure-induced shift (PS) of ZnTe:Mn2+ have uniformly been calculated. The results are in very good agreement with experimental data. According to the eigenfunctions and PS, the assignments of four absorption bands have been given. By taking into account the effect of different deformations of t(2) and e radial wavefunctions on t(2)(3)((4)A(2))e(2)((3)A(2))(4)A(1) and t(2)(3)(E-2)e(2)((3)A(2))E-4, the position of the third absorption band at normal pressure has been estimated. The tetragonal field is important for GSZFS of ZnTe:Mn2+ and its PS, which supports the existence of tetragonal Jahn-Teller distortion in ZnTe:Mn2+. The physical essentials of typical levels, GSZFS and their PS have been revealed.
关键词:
crystal fields;high pressure;optical properties;energy spectrum;Jahn-Teller effect;covalency effect;ZnTe : Mn2+;ligand-field calculation;theoretical calculations;zn1-xmnxte;ruby;epr
Journal of Physics-Condensed Matter
The temperature dependences of the magnetization, internal energy and specific heat in a three-sublattice ferrimagnet or ferromagnet with /J(ab)/ = /J(bc)/ not equal /J(ca)/ are calculated within the framework of the linear spin-wave approximation, by employing retarded Green's functions. For both the ferromagnet and the ferrimagnet, the internal energy and the specific heat decrease with increasing J ' /J and/or the value of the spins. For fixed values of S,, Sb, S, and J ' /J, the internal energy and the specific heat increase, whereas the sublattice magnetization decreases with increasing temperature theta. The three-sublattice ferrimagnet has some particular characteristics which are not shown by the systems with two sublattices. For ferrimagnets, the antiferromagnetism of the system becomes weaker with increasing J ' /J. The sublattice magnetization at low temperatures (also the magnetization M(0) at 0 K) of a ferrimagnet increases with increasing J ' /J for fixed values of S(a), S(b) and S(c). The effects of the spins S(a) (S,) and Sb On the magnetizations of other sublattices differ. The characteristics of the a-sublattice are the same as those of the c-sublattice, due to their similarity as well as the symmetry of the system. The behaviours of the b-sublattice are different from those of the a- and c-sublattices, due to the asymmetry of the three-sublattice system. The spin-value dependences of the spin deviation Deltam per spin land also the energy for the zero-point quantum fluctuation) of the system are different for different sublattices. These differences are ascribed to the asymmetry of the three-sublattice systems, which leads to the new intrinsic properties of the systems.
关键词:
layered heisenberg ferrimagnets;spin-wave theory;elementary;excitations;superlattices;systems;magnetoresistance;antiferromagnet;interfaces
