Liu
,
B.X. Kang
,
X.G. Cao
,
J.L. Huang
,
B. Yinand H.C. Gu (Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)(Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)
金属学报(英文版)
In this paper; the recrystallization process during aging for a rapidly solidified Cu-Cr-Zr-Mg alloy has been investigated. It is found that the discotinuous crystallization process has been partially retarded by the ultra-fine and dispersed precipitation upon aging after deformation. Thus, a phenomenon of combined in situ and discontinuous recrystallization has been observed in the rapidly solidified Cu-Cr-Zr-Mg alloy.On the nucleation and growth of recrystallization, the precipitated phases are coarscned and dissolved in the front of grain boundaries following a re-precipitation in the recrystallization area,which results in the much more dispersed precipitates.
关键词:
rapid solidification; Cu-Cr-Zr-Mg alloy; aging precipitation; recrystallization
X.G. Cao
,
J.L. Huang
金属学报(英文版)
Rapidly quenching embrittlement (RQE) sometimes appears in Fe73.5 Cu1 Nb3Si13.5B9nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism ofRQE has been elucidated in the recent works of current authors. It was believed thatRQE is due to the structural relaxation but not related to α-Fe(Si) crystallization. Inthis paper, the high resolution TEM (HRTEM) method and image digital processingwere applied to analyze the HRTEM images of two FINEMET rapidly quenched rib-bons with different thicknesses in detail. In the thinner ductile sample, the orderingdomains with the size of about 3nm are observed. In the thicker RQE sample, themetastable nanocrystalline domains with the size are 18nm are observed along with thestructural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regionsextend when RQE induced by structural relaxation occurs.
关键词:
HRTEM
,
null
,
null
,
null
,
null
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
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
Y.G. Cao
,
X.Y. Sun
金属学报(英文版)
J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.
关键词:
FRASTA
,
null
,
null
null
,
null
金属学报
在工程上,经常由于应力腐蚀开裂和氢脆引起中强度钢结构件发生滞后破坏。这类脆断往往从结构件中预先存在的疲劳或焊接裂纹处开始,因此,运用传统的光滑试样的检验方法不能反映这类破坏的特点。 本文将弹塑性断裂力学中的J积分概念用于滞后破坏的研究,提出用带预制疲劳裂纹的悬臂弯曲试样测定J积分的临界值J_(Ic)和应力腐蚀开裂阈值J_(Iscc)的方法。测定了40CrNiMo钢的J_(Ic)值及其在硫化氢水溶液中的J_(Iscc)值。通过和三点弯曲方法测定的J_(Ic)值的对比,以及和满足线弹性条件时直接测定的应力强度因子K_I值的对比,说明这种方法的可靠性。最后,对悬臂弯曲方法的特点进行了讨论。
关键词:
慕立俊
,
张军
,
赵文轸
,
张春婉
机械工程材料
利用电化学阻抗谱(EIS)技术研究了J55钢在不同浓度NaHCO3溶液中的腐蚀行为.结果表明:在HCO3-质量浓度为1 g·L-1和5 g·L-1时,J55钢的EIS谱为单容抗弧,其末端收缩程度不同;当HCO3-质量浓度增大到10 g·L-1时,J55钢的E1S谱的高频区是一个容抗弧,低频区为感抗弧;当HCO3-质量浓度增大到30 g·L-1时,阻抗谱由高频区的容抗弧和低频区的Warburg阻抗组成;当HCO3-质量浓度从1 g·L-1增大到5 g·L-1时,弥散指数增大,而从5 g·L-1增大到30 g·L-1时,弥散指数减小;HCO3-质量浓度从1 g·L-1增大到5 g·L-1时,腐蚀速率增大,而从5 g·L-1增大到30 g·L-1时,腐蚀速率减小.
关键词:
J55钢
,
HCO3-
,
电化学阻抗谱
,
腐蚀行为
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
