J.F. Li
,
J.G. Li
,
X.P. Zhang and Y.H. Zhou (School of Materials Science and Engineering
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China)
金属学报(英文版)
Bulk Fe-30Ni alloy melt was nudercooled up to 337K by combining the glass fluxing technique with superheating-cooling cycle. Grain refinement at low undercoolings was observed in the experiment in addition to that at high undercoolings. The current grain refinement mechanisms were examined, and it is concluded that the refined gains are all developed from dendrites, however the grain refinement at low undercoolings is due to chemical superheating, while that at high undercoolings due to rapid solidification contruction.
关键词:
Fe-Ni alloy
,
null
,
null
Z.M. Xu
,
T.X. Li
,
J.G. Li
金属学报(英文版)
A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe, Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. The quantity of in situ granular eutectic reaches up to 8% 12%, and its grain size is in the range from 10μm to 20μm. The austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. The wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.
关键词:
steel matrix composite
,
null
,
null
崔岩
,
鲁二敬
,
吴晓明
,
张艳辉
,
吴昊
机械工程材料
通过拉伸、冲击、弯曲、硬度和金相等试验对S355J2G3低合金钢MAG焊焊接接头的力学性能与显微组织进行了研究。结果表明：采用G383G3Sil焊丝对S355J2G3低合金钢进行焊接时，可获得拉伸、弯曲和冲击性能均良好的焊接接头；接头硬度的分布较均匀，最高不大于380HV；焊缝组织为沿柱状晶晶界析出的块状先共析铁素体，晶内为细小密集的针状铁素体和少量珠光体；热影响区组织主要为先共析铁素体、针状铁素体、珠光体和少量的粒状贝氏体；母材为均匀细小分布的铁素体和珠光体。
关键词:
S355J2G3低合金钢
,
焊接接头
,
力学性能
,
显微组织
Physica B-Condensed Matter
The high-order perturbation formulas for the zero-field splitting parameters D and E, and g factor g(x), g(y), g(z) for 3d(3) ions in rhombic symmetry are derived by using a two spin-orbit coupling parameter model, in which both the contributions from the spin-orbit coupling of central d(3) ion and that of the ligands are considered. From these formulas, spin Hamiltonian parameters for the rhombic defect centers Cr3+-Li+ and Cr3+-Na+ in Cs2CdC4, crystals are calculated by considering the suitable defect-induced lattice distortions. The results agree well with the observed values. The contributions to spin Hamiltonian parameters from the spin-orbit coupling of ligands are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.
关键词:
crystal- and ligand-field theory;electron paramagnetic resonance;spin-orbit coupling;Cr3+;Cs2CdCl4;superposition model;ions
Doris Smith
,
Ken Lynam
环境化学
本文中使用安捷伦SPEC C18AR固相萃取膜盘成功萃取了水中的有机氯农药残留和除草剂.使用双柱配置的GC/μECD系统进行检测,安捷伦J&W DB-35ms UI超高惰性色谱柱作为分析柱,DB-XLB色谱柱为确认柱.该方法为浓度接近或低于最大污染限值的含氯有机物提供了高度灵敏的分析方法.根据预估的分析物萃取浓度,方法使用的校准范围为1-100 ng· mL-1.分别对0.01 μg·L-1的加标水样和一个自来水水样进行了萃取和分析,结果证明可满足水中的有机氯农药残留和除草剂的测定.
关键词:
有机氯农药
,
除草剂
,
色谱柱
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
阎峰云
,
刘兰
,
夏心俊
,
何玲
功能材料
doi:10.3969/j.issn.1001-9731.2017.02.032
采用化学共沉淀法制备出SrAl2O4∶Eu3+红色荧光粉,尝试向粉体中添加辅助激活剂(Li+、Na+、K+),改变粉体中基质元素相对比例,并对粉体进行XRD、荧光光谱分析.结果表明,样品中加入相同摩尔的Li+、Na+、K+辅助激活剂,掺入Li+的粉体发光强度最好.改变Li+的掺入量,当Li+的量为0.04 mol时,粉体发光强度最好.改变粉体中基质Sr2+的含量,当掺入Ba2+时,荧光粉发射峰出现"蓝移"现象;当掺入Ca2+时,荧光粉发射峰出现"红移"现象.
关键词:
共沉淀
,
红色荧光粉
,
辅助激活剂
,
基质
