机械合金化Fe100-xCux体系的X射线吸收精细结构研究

利用X射线吸收精细结构(XAFS)方法研究机械合金化制备的Fe_100-xCu_x(x=0,10,20,40,60,70,80,100,x为原子百分比)合金中Fe和Cu原子的局域环境结构.对于Fe_100-xCu_x(x≥40)二元混合物,球磨160h后,Fe原子的近邻配位结构从bcc转变为fcc,但Cu原子的近邻结构保持其fcc不变.与之相反,在Fe₈₀Cu₂₀和Fe₉₀Cu₁₀(x≤20)合金中,Fe原子的近邻配位保持其bcc结构而Cu原子的近邻配位结构从fcc转变为bcc结构.XAFS结果还表明,fcc结构的Fe_100-xCu_x样品中Fe的无序因子σ(0.0099nm)比bcc结构的Fe_100-xCu_x中的σ(0.0081nm)大得多;并且在机械合金化Fe_100-xCu_x(x≥40)样品中Fe原子的σ(0.0099nm)比其Cu原子的σ(0.0089nm)大.这表明机械合金化Fe_100-xCu_x样品中Fe和Cu原子可以有相同的局域结构环境但不是均匀的过饱和固溶体,而是由Fe富集区和Cu富集区组成的合金.我们提出互扩散和诱导相变机理来解释在球磨过程中Fe_100-xCu_x合金产生从bcc到fcc和从fcc到bcc变化的结构相变 关键词： XAFS 100-xCu_x合金')" href="#">Fe_100-xCu_x合金 机械合金化     

DDT管材料对颗粒状RDX床燃烧转爆轰（DDT）影响的实验研究

 采用盖帽探针、离子探针实验研究了点火药点燃时,DDT管材料变化（钢和铝）对颗粒状RDX床的燃烧转爆轰的影响。     

名校基础知识自测 高二年级

一、选择题椭圆a2扩一的值为(冬犷一1的一个焦点是(一2,0),则‘(A)(C)1一万 4一1士万 41一万 4一1士万 4、lj、,BD了、了叮、2.双曲线的一个焦点是(甲产丽,。),两条渐近线方程是 3x士Zy一。,则两准线间的距离是().‘A,击俪(C,矗俪旦、,顺百13甲一冀、烦百13一BD了、/.、3.过抛物线少~4x的焦点作直线l,交抛物线于A、B 两点,若AB中点的横坐标为3,则}ABI等于 (). (A)10(B)8(C)6(D)44.两个共扼双曲线的离心率分别为e;,e:则有 ().(A)e、=eZ(c)生 生一1(B)el .eZ=心1仑2(D)粤十粤 Cl已25.已知椭圆茸 其一1(。>b>。),椭圆G和已知椭 a一…     

连续浸提-分光光度法测定硼泥中不同形态的硼

采用连续浸提法将硼泥中的硼划分为七种物理形态,即:水溶态、醇溶态、盐溶态、络合态、硫酸盐等结合态、Fe-Mn结合态及残渣态。用分光光度法测定各形态硼的含量。测定结果的相对标准偏差为4.4%(n=4),回收率为91.7%~102.4%。     

微扫描对光电成像系统图像噪声的影响

介绍了光电成像系统的噪声,运用功率谱分析方法推导了插值技术对噪声的影响。插值技术使时间噪声的功率谱变大,使固定模式噪声功率谱的谱值出现再分配,引起图像质量的改善。用计算机进行了模拟实验。     

High beam quality broad-area diode lasers by spectral beam combining with double filters

A modified spectral beam combining(SBC) approach based on double asymmetrical filters was proposed. By using this scheme, the high-order lateral modes at the edge of the far-field pattern can be suppressed in the external cavity, and the beam quality in the slow-axis direction was improved from 16.1 to 13.4 compared to the conventional SBC. In the meanwhile, the electrical-to-optical efficiency from the modified SBC was more than 40% with an output power of 34.1 W, which is similar to that of the conventional SBC.     

Sphere-cone-polynomial special window with good aberration characteristic

Optical windows with external surfaces shaped to satisfy operational environment needs are known as special windows. A novel special window, a sphere-cone-polynomial (SCP) window, is proposed. The formulas of this window shape are given. An SCP MgF2 window with a fineness ratio of 1.33 is designed as an example. The field-of-regard (FOR) angle is ±75°. From the window system simulation results obtained with the calculated fluid dynamics (CFD) and optical design software, we find that compared to the conventional window forms, the SCP shape can not only introduce relatively less drag in the airflow, but also have the minimal effect on imaging. So the SCP window optical system can achieve a high image quality across a super wide FOR without adding extra aberration correctors. The tolerance analysis results show that the optical performance can be maintained with a reasonable fabricating tolerance to manufacturing errors.     

含钼碱性电解液中乙醇在铂黑电极上氧化循环伏安曲线的2,3,5周期及非周期振荡

中图分类号Ｏ６５７·１４文献标识码Ａ通常乙醇在铂黑电极上氧化的循环伏安曲线在经过开始的一段过渡期后会变得稳定，但在特定的条件下也会出现不稳定的振荡现象〔１～５〕．由于钼的存在可以促进有机小分子氧化过程中强吸附物种的氧化，降低过电位〔６〕，因此我们设想...