Ordering transformation in icosahedral quasicrystals and related crystalline phases

Arcs of diffuse intensity appear in various shapes and positions in the diffraction patterns from the icosahedral phase, violating the parity rule for simple icosahedral (SI) symmetry. In the process of annealing treatment, the diffuse spots also evolve in the centre of the arcs and become sharp. These extra diffuse spots change the symmetry of the quasilattice fromP-type toF-type. The ordered and disordered structures in quasicrystal have been linked to the ordered and disordered structures present in the crystalline α (Al-Mn-Si) and α (Al-Fe-Si) alloys.     

Morphology of ordering Fe-Si alloys

The microstructure of some Fe-Si alloys water-quenched from 700–1200°C and aged at 550–675°C for various times has been studied by means of transmission electron microscopy (TEM). It has been shown that at temperatures of 700°C and above the microstructure of the alloy is a solid solution with two-dimensional particles of a B2 ordered phase. These particles have a FeSi composition and lie along (100) planes of the matrix. At temperatures of 675°C and below a modulated microstructure is formed; in its enriched modulations the composition of the Fe₃Si phase is attained and D0₃ ordering occurs. Phase composition of some high-silicon alloys has been determined by X-ray diffraction phase analysis. It corresponds to + B2 or + D0₃. These results are plotted on the accepted Fe-Si phase diagram.     

机械合金化法制备Cr掺杂Fe-Si合金

采用高能行星式球磨机制备了Cr掺杂Fe-Si混合粉,用X射线衍射（XRD）测试研究Cr掺杂Fe-Si合金的机械合金化过程,实验结果表明,随着球磨强度的增加,Fe、Cr、Si粉末通过原子扩散实现机械合金化,最佳的球磨工艺参数为：球磨时间35h、球磨机转速360r/min、球料比40：1。     

Effect of oblique-angle deposition on early stage of Fe-Si growth

We have investigated the initial stage of Fe growth on an Si substrate during reactive oblique-angle deposition (ROAD) at 470 °C by means of atomic force microscopy, reflection high-energy electron diffraction, and high-resolution Rutherford backscattering spectroscopy. During deposition along the normal direction, many Si atoms are displaced from their lattice positions because of reactions with the deposited Fe. However, for ROAD, the number of displaced Si atoms decreases significantly along with a selective growth of nanoislands with diameters of a few 10 nm. Evidently, the local nucleation processes required for iron silicide formation are modified by the geometrical deposition conditions.     

Microstructure characterization of fluidized bed nitrided Fe-Si and Fe-Si-Al foils

This work deals with the structural modifications of FeSi and FeSiAl foils when subjected to a thermochemical nitriding treatment (TNT) performed in a fluidized-bed laboratory furnace. The investigations on the nitrided samples were carried out by optical and SEM microscopic observations, X-ray diffraction and Mössbauer spectroscopy. Both the compound and diffusion layers were investigated.     

Reactions of slip dislocations with twin boundary in Fe-Si bicrystals

Specimens for in situ TEM straining were prepared from Fe-5.5 at.%Si Σ 3 bicrystals with {112} grain boundary plane. They were strained under three different directions of the stress at the boundary with respect to the orientation of the grains. Transfer of slip across the boundary was analysed. In one case, the transfer of slip was realized by a transformation of the slip dislocation in one grain into the slip dislocation in the other grain. Low energy dislocation was created in the GB in accordance with general transfer criteria. In the second case, the incoming and outgoing slip systems were in direct contraction to the general transfer criteria. In the third case, oriented for common slip system in both grains, the trapped incoming slip dislocations dissociated into twinning dislocations which created twins on the other side of the boundary.     

Fe-Si磁性颗粒/环氧树脂复合材料的冲击和磁学性能

采用双酚A型WSR-615和缩水甘油胺型AG-80环氧树脂为基体,以Fe-Si磁性颗粒为填料,通过热压成型方法制备了高含量磁性Fe-Si颗粒/环氧树脂复合材料。研究了环氧树脂基体的玻璃化温度和冲击强度及Fe-Si磁性颗粒含量对Fe-Si/环氧树脂复合材料的冲击强度和磁化强度的影响及温度敏感性。研究结果表明：随着磁性颗粒含量的增加,Fe-Si/环氧树脂复合材料的冲击强度和磁性能增加。当磁性颗粒体积分数由54 vol%增加到66 vol% 时,Fe-Si/环氧树脂的冲击强度和饱和磁化强度分别由4.03 kJ/m²和162.07 emu/g增加到7.16 kJ/m²和175.04 emu/g。Fe-Si/环氧复合材料在-60 ℃~140 ℃ 范围内的温度敏感性低,符合实际应用对复合材料稳定性的要求。     

Ordering of Glassy Alloys

The short-range ordering and acoustic properties of Fe-base glassy and ordered alloys are studied. The role of ordering in crystallization processes is examined, and structural analogs are considered. The experimental data are compared with calculations in a dynamic model.     

考虑批量订货成本的最优JIT订货与生产策略

由于增大单次订单量会降低企业订货灵活性,为此引入批量订货成本来衡量采购商从下达订单到收货期间所面临的与订货批量相关的风险成本。采购商通过综合权衡订货成本、运输成本、库存成本以及批量订货成本,从而得出合理的最优订货批量。基于由采购商和供应商组成的供应链,首先在JIT批量分解模式下,研究考虑批量订货成本后,集中式决策和分散式决策下的最优订货和生产策略。由于分散式决策下一方利益最大化时的最优决策常常是另一方无法接受的,进而分析了上下游企业间的不同议价能力,给出了双方均可接受的订货与生产策略。     

Effects of High Magnetic Field on Recrystallization Behavior in Fe-Si Alloys

Effects of high magnetic field on recrystallization, coarsening after primary recrystallization and texture evolution were studied in non-oriented and oriented 3% silicon steels. The highest applied magnetic field strength was 10 Tesla. It was found that primary recrystallization process and coarsening after primary recrystallization are both retarded by the application of magnetic field during annealing. A difference between primary recrystallization textures annealed with or without a magnetic field was found in both non-oriented and oriented 3% silicon specimens. It was found that the amount of texture component { 111 }<112> increases by the application of magnetic field during annealing.     

Ordering of free-standing Co nanoparticles

Colloidal Co particles of 11 nm diameter were deposited on Si substrate by spin coating and/or casting in magnetic field. A perpendicular magnetic field varying along the diagonal of the substrate was also applied. The samples were analyzed by transmission electron microscopy (TEM), field emission gun scanning electron microscopy (SEM-FEG), atomic and magnetic force microscopy (AFM/MFM). TEM micrographs show local order when a Co nanoparticle monolayer is deposited on Si. Drying the colloidal solution in a magnetic field leads to the formation of quite large clusters (0.3 μm) of Co nanoparticles. A stripe structure was then observed when the particles were deposited by casting in the varying magnetic field. AFM/MFM measurements show isolated Co clusters on the stripes. Magnetic features corresponding to the single Co cluster have been observed pointing out that all magnetic moments in the cluster are oriented along the field direction.     

关于DMRL序关系的几个性质

证明了ＤＭＲＬ序关系在平移变换下的不变性,并获得了一个充分必要条件,作为应用,进上步刻划了该序关系在更新过程中的行为特征。     

The role of stress state on hydrogen cracking in Fe-Si single crystals

While state-of-stress effects have long been known to play a major role in hydrogen embrittlement, there has been little direct evidence outside of thickness effects on threshold stress intensities. Also, there have been recent mechanisms proposed suggesting that enhanced plasticity effects may be more dominant than enhanced decohesion effects. If true, this would mandate different state of stress effects. The goal here was to settle this issue in at least one material, that being a semi-ductile, iron base single crystal. This was achieved by examining the crack initiation site under various loading and hydrogen interaction conditions in precracked Fe-3wt.%Si single crystals oriented in {001}<010> and {001}<110>. A strong dependency of hydrogen-induced cracking on the state of stress was evidenced by the consistent nature of a mid-section initiation stage and tunneling behaviour during crack propagation. This plane stress vs plane strain effect was quantified by analysing both small scale yielding and discretized dislocation computer solutions of the stress field. It was shown that the former did not provide sufficient stress and hydrogen in the local sense while the latter provided both high stress and hydrogen enrichment to cause decohesion. Finally, an assessment is made as to whether surface observations are helpful in sorting out the micromechanical aspects of cracking. This is addressed by examining surface plasticity with respect to the interior crack profile.     

铁硅二元合金在液锌中的腐蚀行为研究

研究了3种不同Si含量的铁硅二元合金在450℃液锌中的腐蚀行为,包括腐蚀速率、腐蚀层组织形貌和成分分析,探讨了Si对铁锌相层的影响规律.结果表明,随着硅含量的升高,腐蚀速率先升高后降低,Fe-l.5Si二元合金的腐蚀速率最高,为0.1617g/(cm2·h).硅的存在导致形成颗粒状的ζ相+η相的蜂窝状的两相混合组织, 使合金表现出最差的耐锌腐蚀能力.     

可变提前期下采购商独立订货及联合订货研究

假设订货提前期是与订货量相关的"U"型函数,这种提前期形式在生产交易中比较普遍。在此种提前期形式下,对于包含一个供应商和两个采购商的供应链,分别考虑采购商独立订货及联合订货的情形,构造数学优化模型。通过分析模型的性质,使用基于Lipschitzian优化的Direct算法求解,以求得模型的最优解。在实际应用中,可以根据提前期与订货量的数据拟合成"U"型函数,利用本文的模型和算法求解。数值分析表明,"U"型提前期下,供应商可以故意拖延,迫使采购商增加订货量;采购商可以与其他采购商联合订货,从而缩短提前期来节约总成本;最后,还分析了"U"型提前期存在的原因。     

低能离子束方法制备磁性Fe-Si合金薄膜

利用质量分离的低能离子束技术．获得了磁性Fe-Si合金薄膜。利用俄歇电子能谱法(AES)、X射线衍射法(XRD)以及交变梯度样品磁强计(AGM)测试了样品的组分、结构以及磁特性。测试结果表明在室温下制备的Fe-Si合金是Fe组分渐变的非晶薄膜,具有室温铁磁性。当衬底温度为300℃时制备的非晶Fe-Si薄膜中有Fe硅化物FeSi相产生．样品的铁磁性被抑制。