R González
,
J O García
,
M A Barbés
,
et al
钢铁研究学报(英文版)
This research shows, through the analysis of three steels that comply with the EN 10149-2 Euronorm, examples of ultrafine grained (or ultrafine ferrite) ferrous alloys, with ASTM grain sizes close to 14 (2 3 m). These steels are microalloyed with Ti-Nb and have been produced by advanced hot rolling controlled techniques in the factories of ArcelorMittal de Avilés (Asturias, Spain) and are mostly used in automotive and construction applications. By comparison, other techniques to obtain ultrafine grained steels are mentioned, though they have not yet reached the industrial level and are produced in laboratories due to the fact that their mechanical properties (low strain hardening coefficient "n") don't allow cold working operations such as bending, stretching nor drawing.
关键词:
ultrafine steels;metallography;strain hardening;Euronorm
陈月娥
,
侯蓝田
材料导报
应用MATLAB软件对自然界中常用的15种稀土离子掺杂的光谱特性进行编程实现,光谱分析应用J-O理论给出智能化的输入输出界面,实现直接挂靠在吸收光谱仪后,使用者即使对J-O理论和计算机程序不了解,仍能正常使用,这样不仅扩大了稀土光谱分析在其他领域的应用,而且也使只关心光谱特性的研究者可以跨过J-O理论和计算机程序部分.此二次开发的模块可与玻璃计算软件联合应用进一步得到玻璃的光谱特性,为新型玻璃的开发提供指导.
关键词:
MATLAB
,
稀土掺杂
,
J-O理论
,
智能界面
吴爽爽
,
莫兴婵
,
韦成峰
,
韦小圆
,
朱文凤
,
覃远东
,
刘来君
材料导报
采用传统的固相反应法制备了Cu欠量的CaCu3 Ti4 O12 (CaCu2.7Ti4 O12)陶瓷,研究了不同烧结时间对CaCu2.7Ti4O12相结构、显微形貌、介电性能和J-E非线性特征的影响.结果表明,延长保温时间降低了CaCu2.7-Ti4 O12陶瓷的中低频介电损耗和击穿场强并且显著提高了其介电常数.采用肖特基热电子发射模型对其非线性特征和电学性能的变化机理进行了分析,认为耗尽层宽度是影响电学性能的主要因素.保温30 h的CaCu2.7Ti4 O12陶瓷有望作为低压压敏电阻应用于半导体电路中.
关键词:
CCTO陶瓷
,
电流-电压非线性
,
压敏电阻器
,
巨介电响应
臧超飞
,
何豫生
,
沈庆飞
,
昌俊
,
李春光
,
张国华
,
罗胜
,
齐志
,
尹道乐
,
丁克俭
低温物理学报
doi:10.3969/j.issn.1000-3258.2001.04.008
我们应用脉冲电流的方法测量了Bi2Sr2CaCu2O8单晶在4特斯拉强场下的大电流时等温E-J特性.我们观察到在大电流时,样品电阻率ρ迅速增大,随着电流的继续上升,经过一段正曲率增长阶段,几乎达到饱和值,最后经过一段负曲率上升,达到正常态,显示出完整的S形.应用尹道乐等人的统一物质方程理论,给出了实验曲线较好的数值拟合.根据拟合结果,讨论了理论中各个参量的物理意义.
关键词:
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
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
李金灵
,
朱世东
,
屈撑囤
,
尹志福
,
卢永斌
,
刘立
腐蚀学报（英文）
综述了J55油套管钢腐蚀的研究进展,提供了影响J55油套管钢腐蚀的关键因素.研究发现,在温度、CO2分压、流速、矿化度、Cl、HCO3和时间条件下J55油套管钢的腐蚀速率均呈现极值,酸化液、硫酸盐还原菌(SRB)以及拉应力加速腐蚀,而微量H2S、pH值、嗜油好氧细菌、压和弯曲应力减缓腐蚀;腐蚀产物膜的成分与结构因腐蚀环境不同而各异,致密、结合力强的膜才能抑制腐蚀;原油、H2S和O2的加入改变反应的传质过程和界面状态.
关键词:
J55油套管钢
,
腐蚀
,
影响因素
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:
