S. Q. Yang
,
Z. Dong
,
J. C. Yan and J. B. Ju( National Key Laboratory of Advanced Welding Production Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
The energy conversion during ultrasonic plastic welding is analyzed on the basis of the theory of vis- coelastic mechanics,.The temperature field and the temperature change of the ABS specimen with ener- gy director during ultrasonic welding is simulated with finite element method(FEM). In the simu- lation process,the melting of the energy energy is also considered. The calculation results are in good agreement with the temperature measurement results, which proves that the simulation results are reli- able.
关键词:
ultrasonic plastic welding
,
null
,
null
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
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
吉日木图
原子核物理评论
研究自旋和轨道量子数不同的介子之间的质量劈裂对检验夸克势模型非常重要.在以往的夸克势模型计算中,η_c-J/ψ的质量劈裂都很难达到实验的值.用正规化形状因μ~2/(q~2+μ~2),在对完整的动量空间中的Breit夸克势实施一次正规化下研究了η_c-J/ψ和新介子ηb与Υ(1s)之间的质量劈裂.结果表明,正规化形状因子中的屏蔽质量μ应与介子折合质量有关,当将其展开为介子折合质量的三阶多项式时,上述介子质量劈裂可以精确重现实验的结果.另外,由于完整的Breit 势包含有自旋一轨道耦合相互作用的项,因而还可以研究χ_(c0),χ_(c1)和χ_(c2)之间的质量劈裂.
关键词:
夸克势模型
,
矩阵元
,
介子束缚态
,
正规化
,
质量劈裂
姜志进
原子核物理评论
在核吸收与随动者吸收理论的基础上,给出了在有QGP相变情况下高能重离子碰撞中的J/Ψ微分产生截面,并用其讨论了CERN的NA50合作组给出的入射动量为158 AGeV/c的Pb-Pb碰撞中的J/Ψ反常抑制现象。理论较好地解释了实验结果。
关键词:
J/Ψ反常抑制
,
核吸收
,
随动者
梁浩
,
赵明久
,
陈胜虎
,
徐勇
,
王永利
,
戎利建
金属学报
doi:10.11900/0412.1961.2015.00255
采用OM,SEM,TEM,EPMA和二次离子质谱(SIMS)等手段,研究了B对J75抗氢合金晶界η相析出的抑制作用机制,采用饱和热充氢、三维原子探针(3DAP)技术和氢渗透实验方法,研究了B对合金抗氢性能的影响机制.结果表明,不含B合金中存在Ti的晶界偏聚,导致晶界7相在时效过程中析出;含B合金中,由于B抑制了Ti的晶界偏聚,使玎相难以形核长大,从而抑制了晶界η相的析出.B和H原子存在位置竞争关系,B降低合金的氢扩散系数,阻碍H原子的扩散和迁移,减少晶界偏聚H原子数量,抑制氢致裂纹形成.
关键词:
J75合金
,
B
,
抗氢性能
,
η相
Physical Review B
The Hamiltonian for a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab) = J(cd) not equal J(bc) = J(da)) was established. An extended Bogoliubov transformation was developed by solving an equation group, consisting of 20 equations and 20 unknowns. The procedure for solving the equation group was carried out by introducing a simple way of reducing the numbers of the equations and the unknowns. The spin-wave spectra in the present system have been determined by performing the standard Holstein-Primakoff transformation and the Bogoliubov one. It has been found that the spin-wave spectra of the present system depend on the exchange constants and that the degeneracy of the spin-wave spectra remains. The results for a special case (J(ab) = J(bc)) i.e., an antiferromagnet are discussed briefly. The spin-wave spectra of the four-sublattice Heisenberg antiferromagnet are found to be degenerative also and they are linear in k for small k.
关键词:
model
董元篪
,
魏寿昆
,
彭(忄育)强
,
朱元凯
金属学报
<正> As一向认为是钢铁中的有害元素。除少数耐腐蚀钢种外,脱As是钢铁冶炼的一个问题。欲脱As必先知As在铁液中的热力学行为。文献中只报道过As的活度相互作用系数e_(As)~C,e_(As)~S及e_(As)~N。本文是继续前文研究As在Fe液中的热力学行为,旨在利用下列反应: 3(CaC_2)+2[As]=(Ca_3As_2)+6[C] (1) 求出Fe-As-C-j熔体中的
关键词:
陈建刚
,
卢凤双
,
张敬霖
,
张建生
,
张建福
金属功能材料
3J33(C)马氏体时效钢是以无碳(或超低碳)铁镍马氏体为基体的时效强化型高弹性合金.采用工业电炉处理合金,高温固溶处理后,再经过4次变温循环相变,基体组织由高温固溶后220 μm的粗大等轴晶细化为15 μm左右的均匀细小晶粒.进一步时效处理后,合金抗拉强度、屈服强度、弹性极限、硬度提高10%以上,断面收缩率、断后伸长率、冲击吸收功提高30%以上.
关键词:
马氏体时效钢
,
变温循环相变
,
时效
,
力学性能
