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镝氢化物掺杂钕铁硼稀土永磁体的研究

向丽君 , P.J.McGuiness , Robin Stuart Mottram , 闫阿儒 , 胡伯平 , 严高林

中国稀土学报 doi:10.11785/S1000-4343.20140505

发现了采用减量化重稀土镝添加高效制备块状超高矫顽力稀土永磁体新型方法.在钕铁硼(Nd-Fe-B)系稀土永磁材料中以DyH3的形式掺入稀土镝(Dy)元素,在不同烧结温度1020,1040,1050,1060,1080℃下进行烧结,制备成一系列DyH3掺杂(PrNd) 30 Fe69B磁体和未掺杂的(PrNd) 30 Fe69B磁体.研究剩磁、矫顽力与烧结温度及显微结构之间的关系.结果显示:随着温度的升高,剩磁不断上升;矫顽力在烧结温度1020 ～1050℃时达到最大.重稀土Dy添加可有效增加Nd-Fe-B磁体的矫顽力.采用扫描电镜和能谱仪研究了不同烧结温度对磁体晶粒尺寸、Dy在晶粒内与晶界处成分分布的影响,发现温度超过1060℃时,晶粒会过度长大,使其矫顽力随之下降.稍低的烧结温度1020～1050℃可以获得Dy分布于晶粒呈“壳”状结构并使得Dy尽量分布于晶界处,获得了制备高矫顽力块体稀土永磁较满意的Dy减量化方法.

关键词: 镝 , 钕铁硼 , 矫顽力 , 烧结 , 稀土氢化物

pp和p碰撞中J/ψ的光生过程（英文）

朱佳庆 , 何俊伟 , 李云德

原子核物理评论

计算了pp和p碰撞中J/ψ的领头阶光生过程的产额。运用非相对论量子色动力学回顾了重夸克偶素产生的色单态机制与色八重态机制,并将它们分别用于处理直接光子过程和分解光子过程。通过与J/ψ产生的领头阶结果的对比可以看出,光生过程对J/ψ产额的修正在大横动量区域变得明显。

关键词: 光生过程 , 大横动量区域 , 重夸克偶素

J4不锈钢及化学镀Ni-P和Ni-Cu-P镀层在液-固两相流中的冲刷腐蚀行为

方信贤白允强王章忠

金属学报 doi:10.3724/SP.J.1037.2009.00499

用质量损失法系统研究了不同温度(25和50℃)和不同冲刷速率(0.63-1.88 m/s)下,J4不锈钢、Ni-P和Ni-Cu-P合金镀层, 及对比材料316L不锈钢在液-固两相流(20% H₂SO₄+20 g/L Al₂O₃)中的冲刷腐蚀行为. 结果表明:不锈钢和镀层的抗冲刷腐蚀性能由高到低依次为镀态Ni-Cu-P, 镀态Ni-P,热处理态Ni-Cu-P, 316L, J4. 提高两相流介质温度均使它们的冲刷腐蚀速率增大. 316L不锈钢在25℃液-固两相流介质中的冲刷腐蚀速率分别为镀态Ni-Cu-P, 镀态Ni-P和热处理态Ni-Cu-P镀层的8.5倍, 8倍和2.6倍以上, 而在50℃下分别为392倍, 80倍和14.8倍以上; J4不锈钢在25和50℃液-固两相流介质中的冲刷腐蚀速率分别为316L不锈钢的28倍和13倍以上. 在25和50℃, J4不锈钢分别为选择性腐蚀和均匀腐蚀, 而316L不锈钢均为轻微选择性腐蚀, Ni-P和Ni-Cu-P合金镀层均为均匀腐蚀.

关键词: Ni-Cu-P , Ni–P , J4 stainless steel , 316L stainless steel , liquid–solid two–phase flow , erosion and corrosion

J4不锈钢及化学镀Ni-P和Ni-Cu-P镀层在液-固两相流中的冲刷腐蚀行为

方信贤 , 白允强 , 王章忠

金属学报 doi:10.3724/SP.J.1037.2009.00499

用质量损失法系统研究了不同温度(25和50℃)和不同冲刷速率(0.63-1.88 m/s)下,J4不锈钢,Ni-P和Ni-Cu-P合金镀层,及对比材料316L不锈钢在液-固两相流(20%H_2SO_4+20 g/L Al_2O_3)中的冲刷腐蚀行为.结果表明:不锈钢和镀层的抗冲刷腐蚀性能由高到低依次为镀态Ni-Cu-P,镀态Ni-P,热处理态Ni-Cu-P,316L,J4.提高两相流介质温度均使它们的冲刷腐蚀速率增大.316L不锈钢在25℃液-固两相流介质中的冲刷腐蚀速率分别为镀态Ni-Cu-P,镀态Ni-P和热处理态Ni-Cu-P镀层的8.5倍,8倍和2.6倍以上,而在50℃下分别为392倍,80倍和14.8倍以上;J4不锈钢在25和50℃液-固两相流介质中的冲刷腐蚀速率分别为316L不锈钢的28倍和13倍以上.在25和50℃,J4不锈钢分别为选择性腐蚀和均匀腐蚀,而316L不锈钢均为轻微选择性腐蚀,Ni-P和Ni-Cu-P合金镀层均为均匀腐蚀.

关键词: Ni-Cu-P , Ni-P , J4不锈钢 , 316L不锈钢 , 液-固两相流 , 冲刷腐蚀

J~P assignments of Λ_c~+ baryons

中国物理C

关键词:

J/Ψ衰变的Roper共振态结构的研究

平荣刚

原子核物理评论 doi:10.3969/j.issn.1007-4627.2004.02.026

通过J/Ψ→pp-,pN-*,N*N-*衰变,研究了Roper共振态的混杂态结构对衰变角分布和分支比的影响.计算结果表明,如果Roper共振态为纯混杂态,那么J/Ψ→pN-*,N*N-*的角分布几乎相等,而J/Ψ衰变到混杂态的衰变宽度还不到J/Ψ→pp-的1%,给出了Γ(J/Ψ→ N*p-)/Γ(J/Ψ→pp-)和Γ(J/Ψ→ N*N-*)/Γ(J/Ψ→pp-)随混合参数的变化关系,并讨论了在J/Ψ衰变中研究Roper混杂态结构的可能性.

关键词: Roper共振态结构 , 混杂态 , J/Ψ

Spin waves in a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab)=J(cd)not equal J(bc)=J(da))

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

EFFECT OF SPECIMEN SIZE ON J_R RESISTANCE CURVE

H.P. Chen and Z.J. Deng (State Key Lab. for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China)

金属学报(英文版)

The effect of specimen thinkness on JR resistance curve has been investigated using low and middle strength steels. As the J dominance regime is reached, the initial J-integral values, J(i), are definite even if the elastic component Ji(e) and plastic component Ji(p)vary with the thinkness of specimen. The wider the specimen width, the larger the Ji(e)/Ji and the smaller the Ji(p)/Ji. The crack propagation resistance, dJR/da and dJp/da, decreases, while dJe/da increases linearly with increasing specimen thinness.Based on the above experimental results, an empirical formula dJ/da = α+β. B is given, which can be used to evaluate the safety of practical structural components.A modified J-integral is presented, upon which a new view is Put forward that the increase in crack growth resistance is induced mainly by the increase in the plastic J-integral component with the crack propagation,

关键词: : fracture mechanics , null , null , null

通过J/Ψ→N(N-)M衰变研究N*时的核子极点效应

沈彭年 , 梁伟红 , 邹冰松

原子核物理评论 doi:10.3969/j.issn.1007-4627.2004.02.009

研究了J/Ψ→ p(p-)π衰变过程中核子极点图的贡献,特别是由离壳效应带来的贡献.发现衰变宽度对形状因子是敏感的.在通过用J/Ψ→ p(p-)π衰变研究N*时,核子极点图作为背景道的贡献是非常重要的; 在通过J/Ψ→ p(p-)η和 p(p-)η研究N*时,核子极点图的贡献可忽略不计; 在通过J/Ψ→ p(p-)ω研究N*时,核子极点图有明显的贡献.