Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

Si对热压法制备Ti3SiC2/SiC复合材料的影响

通过热压法制备了Ti3SiC2／SiC复合材料,并通过扩散偶实验及组织观察,探讨了Si元素对热压制备Ti3SiC2／SiC复合材料的反应过程及组织的影响．结果表明,Si元素在反应过程中起主要作用,决定着反应进行的速度与方向．而且随着反应物中Si量的增加,更有利于Ti3SiC2／SiC复合材料的形成．     

Al—12.5Ti混合粉的机械合金化

通过Ｘ射线衍射、扫描电子显微镜及透射电子显微镜方法，观察了Ａｌ－１２．５Ｔｉ混合粉在机械合金化过程中粒度、形貌、显微结构及相的变化．机械合金化扩展了Ｔｉ在Ａｌ中的固溶度，最终形成了纳米晶过饱和固溶体．经真空退火后，Ａｌ基体上析出Ａｌ３Ｔｉ相．     

机械诱发自蔓延反应合成Ti3AlC2的机理研究

以3Ti／Al／2C粉体为原料,采用机械合金化的方法以合成Ti3AlC2材料。研究结果表明,在机械合金化过程中诱发自蔓延反应,反应会产生大量坚硬的小块体颗粒,大小约为0．2-11mm。粉体的组成相为TiC、Ti3AlC2、Ti2AlC,而块体仅含有TiC和Ti3AlC2。获得的粉体和块体产物中Ti3AlC2含量分别约为63wt％和84．8wt％。提出了一个机械诱发自蔓延反应合成Ti3AlC2的反应机制,即Ti3AlC2是从固相TiC与Ti-Al液相中形核并长大。     

α2—Ti3Al的价电子结构及合金化

计算了α2—Ti3Al、合金α2～Ti3Al的价电子结构。利用价电子结构给出的信息一实际可能存在的原子状态组数σN、结构单元总成键能力F、晶格电子密度ρv^L、共价电子密度ρv^c及共价电子的空间分布nα，讨论了α2—Ti3Al、合金α2—Ti3Al的精细价电子结构与合金相稳定性、范性、强度的关系，分析了以Nb为主的合金元素的合金化行为。     

Ti3SiC2的制备方法研究现状

Ti3SiC2材料兼具金属和陶瓷的性能,具有良好的导热性、导电性、自润滑性、耐磨损、高断裂韧性、高温抗氧化等优异性能,有着广阔的应用前景。本文介绍了目前Ti3SiC2材料的制备的方法及其研究现状。     

Electronic Structure and Chemical Bond of Ti3SiC2 and Adding Al Element

The relation among electronic structure, chemical bond and property of Ti3SiC2 and Al-doped was studied by density function and discrete variation （ DFT- DVM） method. When Al element is added into Ti3 SiC2 , there is a less difference of ionic bond, which does not play a leading role to influent the properties. After adding Al, the covalent bond of Al and the near Ti becomes somewhat weaker, but the covalent bond of Al and the Si in the same layer is obviously stronger than that of Si and Si before adding. Therefore, in preparation of Ti3 SiC2 , adding a proper quantity of Al can promote the formation of Ti3 SiC2 . The density of stnte shows that there is a mixed conductor character in both of Ti3 SiC2 and adding Al element. Ti3 SiC2 is with more tendencies to form a semiconductor. The total density of state near Fermi lever after adding Al is larger than that before adding, so the electric conductivity may increase after adding Al.     

Ti3SiC2/TiB2复合材料的制备及其组织和力学性能

以2TiC／Ti／Si／0．2Al／TiB2粉为原料，采用热压烧结工艺成功制备了Ti3SiC2／TiB2复合材料。结果表明：不同TiB2含量的试样中主晶相为Ti3siC2与TiB2两相，没有发现其它杂质相；当复合材料中TiB2的体积分数为10％时，其硬度、抗压强度、弯曲强度、断裂韧性都有显著的提高。经热处理后，Ti3SiC2／10％TiB2复合材料的弯曲强度由367．5MPa     

Formation mechanism of Ti5Si3 powder by mechanical alloying

The formation mechanism of stoichiometry Ti5Si3 by mechanical alloying (MA) from elemental powders has been investigated. The results of XRD and SEM analyses of the powder show that Ti5Si3 can be synthesized by MA in a planetary mill with two different formation mechanisms. Ti5Si3 was formed gradually with the mechanical collusion reaction (MCR) mechanism under a lower impact energy, and the Ti5Si3 was formed abruptly with the self-propagating high-temperature synthesis (SHS) formation mecha-nism under a higher impact energy.     

Ti3SiC2及Ti3SiC2基复合材料的研究现状及发展

介绍了Ti3SiC2陶瓷材料的微观结构与性能，认为该材料良好的综合性能有望解决陶瓷材料的脆性问题．并概述了Ti3SiC2及Ti3SiC2基复合材料各种制备方法的特点和研究状况、应用前景和发展趋势．     

层状三元碳化物Ti3SiC2及其制备研究

三元碳化物Ti3SiC2属于层状六方晶体结构，空间群为P63／mmC；它同时具有金属和陶瓷的优良性能，有良好的导电和导热能力，在室温下可切削加工，在高温下有良好的热稳定性和塑性变形能力，还具有优异的抗氧化性能，抗热震等；应用CVD、SHS、HP／HIP等方法可制备该化合物，用HIP方法能制备高纯、致密的Ti3SiC2陶瓷。最近，以元素单质粉为原料，采用放电等离子烧结工艺成功制备了高纯Ti3SiC2材料。     

Influence of mechanical alloying time on the properties of Fe_3Al intermetallics prepared by spark plasma sintering

The Fe3Al-based intermetallics were prepared by mechanical alloying and spark plasma sintering (SPS), and the influence of milling time on the properties of materials was investigated. The phase identification was investigated by X-ray, and the surface morphology and fractography were observed by scanning electron microscope (SEM). The mechanical properties such as bending strength, strain, and microhardness were tested. The results show that Fe reacts with Al completely to form Fe3Al during short SPS processing time. The relative densities of the sintered samples were nearly 100/. The mechanical properties of the sintered samples can be improved along with the milling time. The representative values are the bend strength of 1327 MPa and the microhardness of 434.     

Electronic Structures and Bonding Properties of Ti_2AlC and Ti_3AlC_2

The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SixAl1-xC has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al 3p.     

Effect of Nb on the Mechanical Properties of Ti／Al2O3 Composite

1　IntroductionMetallic Titanium and alloy are necessary to theaerospace materials because they have excellent propertiesof low density, high strength, and resistance to high tem perature and erosion. And alumina has fine properties ofcalorifics, m…     

Effect of Ti/B Additions on the Formation of Al3 Ti of in situ TiB2/Al Composites

ParticulatereinforcedMetalMatrixComposites(MMCs)showgreatpotentialforstrUctUralmaterialsduetotheirpromisingspecificstrengthandmodlllus.AmongthenumeroustechnologiesproducingparticulatereinforcedMMCs,thoseallowinginsituproductionofthereinforcementoffer...