First Principle Calculation of Electromagnetic Mechanism for Fe_2Si Bulk Material

The electronic structure and the magnetic properties of Fe_2Si bulk have been calculated by the first-principle density function theory method. The band structure shows that the hexagonal Fe~2 Si bulk is ferromagnetic which is a metal structure under spin-up, and a semiconductor with the band gap of 0.518 eV under spin-down. The density of states shows the Fe~1 3d–spin and Fe~3 3d–spin in the electronic system are the main factors that is the source of the ferromagnetic properties of Fe_2Si bulk. The electronic structure Si-ions is 3s23p6 and that of Fe-ions is e_g~2↑e_g~(*1)↓t_(2g)~3↑. The molecular magnetic moment of Fe_2Si is 2.00 μB. The potential diagram of Fe_2Si bulk shows the formation of covalent and ionic bonds between the Fe atom and the Si atom, it leads to the center charge of Fe is polarized and off center position. These special properties of Fe_2Si bulk are mainly caused by d-d exchange and p-d hybridization. The results offer a certain reference for the magnetic semiconductor Fe_2Si material.     

TiC,NbC,VC,B4C超硬质相耐磨堆焊材料的研究

采用钛、铌、钒、硼等铁合金与石墨等材料的混合粉,用TiC,B_4C硬质合金与F101,F314等自溶合金制成混合复合材料,以等离子转移电弧为热源进行了探索性的耐磨堆焊材料的试验研究。通过堆焊时的冶金反应,在堆焊金属中形成了TiC,NbC,VC等碳化物超硬质相,极大的提高了堆焊金属的硬度和耐磨性。试验数据表明,这种堆焊金属的耐磨性均超过国内目前F31,堆667,堆717堆焊材料的耐磨性,为堆焊材料领域开发新型材料提供了新的途径。     

Wear Behavior of In-situ TiC Particles Reinforced Aluminum Matrix Composite

The microstructure, tensile property and wear resistance of 7075 aluminum matrix composite reinforced with TiC particles prepared by in-situ reaction casting were investigated. The effect of TiC reinforcement on wear behavior was analyzed. The wear mechanism was also discussed. A micro-mechanism model of reaction kinetics for synthesis of TiC was acquired. Results show that TiC could increase the tensile and yield strength, but decrease the elongation. Besides, TiC particles improve the property of wear resistance of 7075 aluminum alloy. The wear mechanisms include abrasive wear and adhesive wear in wear test process.     

TiC/Fe-Al复合陶瓷材料量子化学计算研究

用离散变分密度泛函方法研究了TiC、FeAl、Fe3Al和TiC／Fe-Al复合陶瓷材料，讨论了材料组成、结构、化学键与性能等之间的关系。在TiC／FeAl和TiC／Fe3Al复合体系中，界面上两相之间的离子和共价相互作用都较强。从TiC、FeAl和Fe3Al单相，到TiC／FeAl和TiC／Fe3Al复合体系，离子键强度逐渐减弱，而共价键强度逐渐增强。TiC／Fe3Al复合体系中轨道相互作用和共价键比TiC／FeAl的强。这与TiC／Fe-Al系列样品中，随铝含量逐渐减少，即FeAl含量逐渐减少，Fe3Al逐渐增多，抗弯强度等增加的实验结果一致。     

Characteristics of Retained Austenite in TRIP Steels with Bainitic Ferrite Matrix

Heat treatment process for producing cold rolled transformation induced plasticity-aided (TRIP-aided) steels with bainitic ferrite matrix was adopted. Characteristics of retained austenite (RA) in such TRIP steels were investigated. SEM and OM determination results showed that the stable austenite retained at room temperature were mainly located between laths and some of them inside the coarse ferrite. The grains were uniformly distributed in heat treated steel matrix and the regularly dispersed RA represen...     

原位自生TiC和（TiW）C增强Fe基复合材料的研究

利用块体原材料原位合成10vol%TiC-Fe和(TiW)C-Fe两种复合材料,采用扫描电镜分析了复合材料的微观结构,利用X射线分析了相组成。结果表明,在TiC-Fe复合材料中,TiC作为唯一的第二相呈现粒状和条状两种形态。分析认为,粒状相为亚共晶相,而条状第二相为共晶相。通过用W替代部分Ti,成功地制备了10vol%(TiW)C-Fe复合材料,其中,(TiW)C作为唯一的第二相比较均匀地分布在Fe基体中,其形态大部分呈粒状,条状相较少。在粒状(TiW)C相中,中心富Fe,而边缘W、Ti和C元素的分布是均匀的。与TiC相比,(TiW)C的密度与Fe更为接近,它更适合作为大型铸件的增强相。     

Microstruetures and Mechanical Properties of TiC Particle Reinforced TiAl Composites by Spark Plasma Sintering

Using spark plasma sintering（SPS） technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was ahnost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.     

Fuzzy矩阵的亚容度计算

提供了借助于Fuzzy矩阵的Ⅲ型方程来计算Fuzzy矩阵的亚容度的方法，并给出简单易行的Fuzzy矩阵的亚容度为1的判别方法。     

化学沉淀-铁氧体法处理重金属废水试验研究

重金属离子排放到环境中只能改变形态或被转移、稀释、积累,对生物危害很大。为了处理含多种重金属离子的废水,本试验采用化学沉淀-铁氧体法处理主要含铅、锌、镉离子的废水。以云南弛宏锌锗股份有限公司废水为原水,在对影响处理效果的各种要素如温度、pH值、搅拌时间进行了条件试验后,得出了去除重金属离子废水静态试验的最佳条件。     

Microstructures and Mechanical Properties of TiC Particle Reinforced TiAl Composites by Spark Plasma Sintering

Using spark plasma sintering(SPS)technique,TiC particle reinforcedγ-TiAl composites were prepared with varying weight fraction of TiC powders.The effects of the TiC fractions and distributions on the properties of the composites were investigated.The composite containing 7wt%TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforcedγ-TiAl intermetallic.The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC,which acted as crack initiation and propagation sites.The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles.The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa,respectively,by the grain refinement and dislocation strengthening,the total of which was almost in accordance with the improvement in that of the unreinforcedγ-TiAl intermetallic when considering normal estimation errors.     

原位合成TiC/Fe基复合材料的组织结构和磨损性能

利用粉末冶金技术,在真空状态下使Fe-Ti-C体系进行碳化反应原位合成TiC/Fe基复合材料,用扫描电镜(SEM)、X射线衍射(XRD)分析复合材料的组织结构和相组成,用热分析法和高温X射线衍射研究Fe-Ti-C体系原位合成的反应机理,用MM-200磨损试验机对复合材料进行耐磨性实验.研究结果表明,反应合成的复合材料主要相组成为TiC、α-Fe和Fe3C,所合成的硬质相TiC颗粒细小,在铁基体中均匀分布.三元体系Fe-Ti-C的反应机理为,首先在765.6 ℃发生Fe的同素异构转变,即α-Feγ-Fe;其次在1078.4 ℃,Ti与Fe共熔而形成低共熔体Fe2Ti;最后在1138.2 ℃,C与Fe2Ti反应生成TiC.在重载干滑动磨损条件下此复合材料显示了很好的耐磨性能.     

关于质点系动能定理的商榷

质点系动能定理,即理想约束系统的动能的增量等于作用于质点系主动力的元功和。笔者认为,对稳定的理想约束系统是真实的,而对非稳定的理想约束系统则不一定真实。     

Fuzzy对称可实现矩阵容度的计算

本文讨论了 Fuzzy 对称可实现矩阵的容度问题。找出了可计算的一个下界估计,借助于文〔8〕和文〔9〕提出的Ⅱ型 Fuzzy 关系不定方程的求解,给出了计算容度和计算相应的一组实现矩阵的算法。     

铁基复合材料中原位TiC增强颗粒生成机制

在合金熔体中采用不同时间取样，通过液淬的方法，将铁基复合材料的液态合金熔体迅速冷却到室温，固定熔融条件下的形态，观察金相组织，分析其变化情况．结果表明：根据热力学及动力学分析，合金熔体在富碳区TiC的形核率很高，形核驱动力足以在正常熔炼温度下形成众多的小晶核；熔体中TiC颗粒的形成可分为形核与长大阶段，首先活性Ti原子包围C，溶入合金中的Ti与C在碳表面形成一复杂反应中间层，随着反应进行，Ti和C颗粒不断减少，生成的TiC不断弥散分布于熔体中；其长大过程伴随着TiC颗粒的相互堆砌、聚集和形态规则化．     

改进单纯形法中基于新基矩阵的逆矩阵计算

研究了改进单纯形法中基于新基矩阵的逆矩阵计算问题,获得了B-11=EB-1中关于ξ的一般表达式,并且给出了具体算例.     

含磷废水的一级处理--化学沉淀法

以含磷废水为研究体系,研究了以氯化镁、碳酸氢铵为复合沉淀剂去除水中磷过程的工艺条件.该工艺过程保留了化学沉淀法操作弹性大、除磷效率高、操作简单的特点,生成的MgNH4PO4·6H2O结晶大,容易过滤.该除磷体系中最佳的工艺条件为:初始液pH值为9 4,沉淀剂加入量[NH4+]/[P]=1,[Mg2+]/[P]=1 3(摩尔比).     

分块矩阵在行列式及逆矩阵计算中的应用研究

线性代数,尤其是矩阵与行列式在自然科学及工程技术等领域应用广泛。在介绍分块矩阵基本概念的基础上,结合分块矩阵的相关性质,通过具体事例对分块矩阵在高阶矩阵的逆矩阵与高阶行列式中的应用进行分析。     

基于BP神经网络的TRIZ理论冲突矩阵

使用Matlab ANN工具箱，将传统TRIZ理论的核心——冲突矩阵变换为一个以工程参数及其冲突为输入层，以冲突解决原理为输出层，并包括一个隐含层的三层BP人工神经网络模型。该模型基于具有较快收敛速度的改进BP算法——弹性反馈学习算法RPROP，利用已有的发明实例和问题解决方案作为学习样本，使模型的建立及修正更加容易，新问题的解决更具有针对性，为企业应用TRIZ提供一种较为简便的实用方法。根据问题的规模和计算需求确定了网络模型的详细参数，具体给出了由实例到样本的抽象过程。最终运行的结果显示了较好的收敛性和较快的收敛速度，证明了该方法的可行性。     

聚合物基纳米复合材料热导率计算

讨论了聚合物基高导热高绝缘纳米复合材料的导热机理与常用的导热理论模型。考虑到填充率、温度等的影响，用不同的理论模型计算了氧化铝纳米颗粒填充环氧树脂的热导率，并结合相关研究实验对不同的导热理论模型进行分析比较。通过添加高导热填料可显著提高聚合物材料的热导率，且热导率随填料填充率的增大而显著增大。热导率随在300 K到373 K的范围内，复合材料的热导率随着温度的升高而增大；而当温度超过373 K，复合材料的热导率则随着温度的升高缓慢下降。     

声子谱计算中动力学矩阵的约化

以（4,2）型手性碳纳米管为例,介绍利用晶体的对称性建立约化矩阵的方法．通过约化矩阵,将动力学矩阵约化成准对角形式,求解准对角形式的动力学矩阵得到本征值与本征矢．与直接求解动力学矩阵相比,经过约化处理的计算过程大幅度节省计算时间,并且计算结果按振动模对称性排序,省去分析本征矢判断本征值所属振动模对称性的步骤．