(Ti,W)C-Ni金属陶瓷的显微组织和力学性能研究

采用商用(Ti_(0.76),W_(0.24))C、(Ti_(0.69),W_(0.31))C、(Ti_(0.58),W_(0.42))C和Ni粉末,通过真空烧结制备了(Ti,W)C-Ni金属陶瓷。研究了(Ti,W)C中W含量对(Ti,W)C-Ni金属陶瓷显微组织和力学性能的影响。研究结果表明,(Ti,W)C-Ni金属陶瓷具有芯-环结构显微组织。随着W含量升高组织中芯相体积分数下降,环形相体积分数明显上升。当a(Ti)∶a(W)为0.69∶031时,金属陶瓷组织中出现了少量的无芯相,但进一步增加W含量,金属陶瓷中析出WC相和石墨相。较之传统的Ti(C,N)基金属陶瓷,(Ti_(0.69),W_(0.31))C-Ni金属陶瓷具有优异的断裂韧性(KIC),其数值为16.94 MPa·m~(1/2)。环形相与芯相的体积分数比例是影响(Ti,W)CNi金属陶瓷力学性能的关键因素。     

原位烧结合成(Ti,V)C/Fe复合材料的组织及形成机理

以钛粉、铁粉、钒铁粉、铬铁粉、钼铁粉及石墨粉为原料,通过原位烧结制备了(Ti,V)C/Fe复合材料.利用X射线衍射(XRD)、扫描电镜(SEM)和能谱EDS分析了材料的组织结构.结合差示扫描量热法分析(DSC)和高温x射线衍射分析研究了Fe-Ti-V-C体系原位烧结的动力学过程.结果表明:(Ti,V)C/Fe复合材料致密化程度高.增强相(Ti,V)C的形态比TiC更规则,TiC颗粒中存在富Mo的"环形结构",而(Ti,V)C中没有"环形结构".合成(Ti,V)C/Fe复合材料的动力学过程为:在770℃左右发生钒的碳化反应生成VC,1140.4℃时发生Ti的碳化反应生成TiC,随着温度升高,VC和TiC发生固溶反应形成(Ti,V)C固溶体.在1400℃烧结时,硬质相(Ti,V)C(或TiC)在液相中根据Gibbs-Thomson效应,按照小颗粒不断溶解,大颗粒相应粗化的模式长大.     

激光熔覆原位合成TiC/Ti复合材料试验研究

利用激光熔覆技术，在工业纯钛表面原位合成了TiC／Ti复合材料。结果表明：选择不同的激光熔覆工艺参数，可使碳粉和Ti粉通过原位合成反应在钛表面生成TiC／Ti复合材料熔覆层；激光功率和扫描速率是影响熔覆层质量的主要因素：激光功率越大，形成的增强相颗粒尺寸越大，相应合金元素氧化也越严重；扫描速率越大，Ti与C的作用时间变短，增强相颗粒尺寸越细小，且增强相所占的体积分数也相应减少。用XRD、DES和SEM证明了TiC颗粒的存在，同时发现颗粒分布具有一定的均匀性，原位生成的TiC颗粒主要以等轴状和块状两种形态存在。     

热压原位合成TiC-xNi复合材料的组织与性能

以钛粉、石墨、钼粉和镍粉为原料,热压原位合成TiC-xNi复合材料。研究碳钛比及镍含量对热压原位合成TiC-xNi复合材料的组织和力学性能的影响。用扫描电镜和X射线衍射仪对复合材料的组织和物相组成进行分析,测试复合材料的致密度、硬度和抗弯强度。结果表明,热压原位合成的碳化物颗粒比较细小,尺寸为0.5~4μm。碳钛比及镍含量对最终产物的相组成没有影响。随碳钛比的增大(从0.9增大到1.0),热压合成TiC-xNi复合材料的组织变得复杂,出现了亮环形组织、亮核/环形结构组织和灰核/环形结构组织,且碳化物颗粒和粘结相的边界平直化。随着镍含量的增加,复合材料的致密度、硬度和抗弯强度都有所降低,碳钛比对复合材料的致密度和硬度影响不大,但抗弯强度随碳钛比的增大明显减小。热压原位合成TiC-xNi复合材料的弯曲断口以沿晶断裂为主,40vol%TiC-Ni复合材料的断口中还出现了一些撕裂棱。     

原位合成(Ti,V)C/Fe基复合材料

采用粉末冶金与原位合成相结合的方法制备了(Ti,V)C/Fe复合材料,用X射线衍射(XRD)、扫描电镜(SEM)研究了该复合材料的物相结构和显微组织,用MM-200磨损试验机对复合材料进行了耐磨性实验.结果表明,复合材料的相组成为(Ti,V)C和a-Fe;合成的硬质相(Ti,V)C颗粒细小,在珠光体基体中均匀分布;在重载干滑动磨损条件下,该复合材料显示了很好的耐磨性能.     

反应热压(Al2O3+TiB2+Al3Ti)/Al复合材料的组织形成机制

采用B或B2O3、TiO2和Al粉反应热压制备了原位 (Al2O3 TiB2 Al3Ti)/Al复合材料,采用光学显微镜、扫描电镜和透射电镜分析了原位复合材料的显微组织.热压状态下,反应生成相Al3Ti呈大块不规则形状,尺寸约几十微米; Al2O3和TiB2为细小弥散质点,TEM分析发现TiB2颗粒呈六边形,而Al2O3颗粒呈等轴状.在以Al粉、TiO2粉和B粉为原料制备的复合材料中,除反应生成了大块的Al3Ti相外,还有细小针状Al3Ti相沉淀析出,且呈弥散分布.热挤压后大块的Al3Ti被破碎成细小弥散质点.Al2O3在TiO2和B2O3粉末表面生成; TiB2在B或B2O3粉表面形成,因而均呈弥散分布,且尺寸细小.自TiO2中还原出的Ti溶入液态Al中形成Al3Ti时,Ti可在液态Al中长距离扩散,因而Al3Ti呈大块不规则状.     

自生Ti2AlC/TiAl复合材料的组织及反应过程

采用自蔓延燃烧合成及真空电弧熔炼的方法,以碳纤维(Cf)、钛粉及铝粉为原料,合成了Ti2AlC/TiAl复合材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了复合材料的物相组成和微观结构,讨论了原位合成Ti2AlC的反应和二次Ti2AlC的析出过程。结果表明,复合材料铸锭由Ti2AlC、TiAl和Ti3Al3相组成,基体由α2(Ti3Al)+γ(TiAl)片层和γ(TiAl)等轴晶粒构成,原位自生的Ti2AlC分布均匀,呈短纤维状或颗粒状。1200℃均匀化热处理促使Ti3Al分解为TiAl和Ti2AlC,导致Ti2AlC粗化,同时基体表面析出细小的二次Ti2AlC颗粒。     

(Ti,W)C颗粒增强铁基表面复合材料微观组织的研究

利用粉末冶金技术,在45钢表面制备了(Ti,W)C/Fe复合材料,采用扫描电镜(SEM)、X射线衍射(XRD)分析了表面复合材料的微观组织和相组成。结果表明:表面复合材料主要相组成为(Ti,W)C和α-Fe;所合成的硬质相(Ti,W)C颗粒在铁基体中均匀分布;表面复合材料与45钢之间的界面结合良好。     

原位自生TiC和(Ti,W)C增强Fe基复合材料的研究

利用块体原材料原位合成10%TiC-Fe和(Ti,W)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10%(Ti,W)C-Fe复合材料,其中(Ti,W)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(Ti,W)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,(Ti,W)C的密度更接近Fe,更适合作为大型铸件的增强相.     

(Ti,V)C原位烧结钢结硬质合金热处理后的组织与性能

以钛粉、钒铁粉、铬铁粉、钼铁粉、铁粉及石墨粉为原料,在真空烧结炉中原位合成了(Ti,V)c钢结硬质合金.研究了(Ti,V)C钢结硬质合金的热处理组织及力学性能.结果表明,该钢结硬质合金在1000℃淬火后的组织为片状马氏体+(Ti,V)C硬质相颗粒+少量未溶碳化物;经1000 ℃淬火+500℃回火时发生二次硬化现象,硬度达86 HRA左右,抗弯强度达1540MPa,其断口形貌为硬质相解理、基体准解理及韧窝;经1000℃淬火+250℃回火、1000℃淬火+500℃回火后该硬质合金的耐磨性分别是经深冷处理高铬铸铁的3.8和3.5倍,其磨损机理是基体形变磨损和硬质相脱落.     

NiMo粘结的Ti(C,N)基金属陶瓷的组织与力学性能

本文通过粉末冶金法制备Ni Mo粘结的Ti(C,N)基金属陶瓷,研究Ni Mo粘结相含量和烧结温度对Ni Mo粘结的Ti(C,N)基金属陶瓷的组织和力学性能的影响。结果表明,随着Ni Mo粘结相含量的增加,硬质相颗粒弥散分布更加均匀,黑芯相得到细化,芯-环结构更加完整,环形相变厚,组织更加均匀。当Ni质量分数为30%时,在XRD图谱中出现明显的Ni4Mo类型的金属间化合物的衍射峰。粘结相含量越高,Ni Mo粘结的Ti(C,N)基金属陶瓷的抗弯强度越高,硬度越低。随着烧结温度升高,黑芯相尺寸变小,环形相变厚。抗弯强度随着温度先升高后降低,粘结相含量越高,抗弯强度峰值对应的烧结温度越低。1 430℃烧结的20Ni Mo金属陶瓷硬度HRA达到91,抗弯强度大于2 000 MPa。     

Effect of (Ti,W, Mo,V)(C,N) powder size on microstructure and properties of (Ti,W, Mo,V)(C,N)-based cermets

Three kinds of (Ti, 15 W, 5Mo, 0.2 V)(C, N) powders with different particle size were prepared from a mixture of oxides and carbon powders by carbothermal reduction-nitridation method. (Ti, W, Mo, V)(C, N)-based cermets were obtained by mixing Co, Ni, WC, MoC₂ and (Ti, 15 W, 5Mo, 0.2 V)(C, N) powders, and then processed via a conventional P/M technique. The influence of (Ti, 15 W, 5Mo, 0.2 V)(C, N) particle size on the microstructure and mechanical properties of (Ti, 15 W, 5Mo, 0.2 V)(C, N)-5WC-10MoC₂-7Co-8Ni cermets has been studied. When the particle size of (Ti, W, Mo, V)(C, N) is 0.2–0.5 μm, (Ti, 15 W, 5Mo, 0.2 V)(C, N)-based cermets can be characterized by weak core/rim structure. With the particle size of (Ti, W, Mo, V)(C, N) increasing to 1–1.5 μm, the microstructure of (Ti, 15 W, 5Mo, 0.2 V)(C, N)-based cermets develops into composite structure that consists of typical core/rim and no core/rim. Accordingly, typical core/rim structure is obtained in the case of the particle size of 3–5 μm. With the coarsening of raw (Ti, 15 W, 5Mo, 0.2 V)(C, N) powders, the fracture toughness of (Ti, 15 W, 5Mo, 0.2 V)(C, N) cermets is greatly improved, but the hardness continues to decline. (Ti, 15 W, 5Mo, 0.2 V)(C, N) cermets with composite structure have higher bend strength of 2165 MPa.     

Mo对多弧离子镀(Ti,Mo)xN涂层组织与性能的影响

采用Ti/Mo复合靶 ,用多弧离子镀技术沉积了 (Ti,Mo) xN多元涂层 ,研究了Mo对该涂层组织与性能的影响。结果表明 ,涂层的主要结构为 (Ti,Mo) 2 N ,其中Mo的固溶度可达 4 56% (质量分数 ) ,并具有较高的显微硬度、抗氧化性和低的孔隙率。在沉积过程中存在着多元合金涂层与复合靶的成分离析现象 ,这与靶材的结构有关。     

Effect of Ti content and nitrogen on the high-temperature oxidation behavior of (Mo,Ti)5Si3

The binary intermetallic compounds Mo₅Si₃ (T1) and Ti₅Si₃ are prone to rapid oxidation below 1000 °C. Recent investigations on (Mo,Ti)₅Si₃, however, revealed that macro-alloying with 40 at.% Ti can result in a very good oxidation resistance in a wide temperature range (750–1300 °C) due to the formation of a duplex layer composed of a silica matrix with dispersed titania. Additionally, Ti decreases density making (Mo,Ti)₅Si₃ a promising key constituent of quaternary Mo-Si-B-Ti alloys considered for ultrahigh temperature structural applications. The aim of this study is to obtain an in-depth understanding of the influence of different Ti concentrations as well as of nitrogen on the oxidation behavior of (Mo,Ti)₅Si₃ at intermediate and elevated temperatures. The microstructure and oxidation mechanisms were analyzed using various experimental techniques. The experimental results were supported by ab initio and thermodynamic calculations.     

Extraction of Metal(Ti,V,Mo)-oxyl Cations by Monoacidic Phosphates and Phosphonates

The extraction of TiO~(2+),VO~(2+),VO_2~+ and MoO_2~(2+)by HDEHP,HEHEHP and HDTMPP was studiedrespectively.The orders of extraction ability for the three extractant systems are as follows:for TiO~(2+),VO~(2+):HDEHP>HEHEHP>HDTMPP;for VO_2~+, MoO_2~(2+):HDEHP< HEHEHP< HDTMPP.The experimental results were discussed from the point of view of extractant structures.     

Corrosion Behavior and Hardness of Al-M (M:Mo,Si,Ti,Cr) Alloys

The corrosion behavior of Al-5 at.%Cr,Al-5 at.%Si,Al-5 at.%Mo and Al-5 at.%Ti produced via casting and Al-5 at.%Cr produced by high-energy ball milling and subsequent consolidation by cold pressing was studied using potentiodynamic polarization and surface analysis following constant immersion tests.Alloys were characterized using a scanning electron microscope coupled with the energy-dispersive X-ray spectroscopy and X-ray diffraction analysis.Hardness,a representative of the strength,was also measured.The alloys produced by casting contained coarse intermetallics and therefore exhibited poor corrosion resistance.Al-5 at.%Cr alloy produced by high-energy ball milling exhibited a significantly improved corrosion resistance and hardness,which was attributed to the grain refinement to nanoscale and extended solid solubility of Cr in Al.The study indicated that the high-energy ball milling was capable of producing Al alloys with improved corrosion behavior and hardness.     

Mo element-induced wear behavior evolution of self-lubricant Ti(C,N)-based cermets

In the work, Mo element is used to adjust composition and distribution of the lubricating phase of the self-lubricant Ti(C, N)-based cermets. Ring-block wear test of self-mate pairs is conducted. The microstructure and wear behavior evolution of the cermets are investigated. The results indicate by adjusting the content of Mo, the distribution of graphite on the surface of the self-lubricant cermets changes. With the increase of Mo content, the volume of graphite decrease, and the undissolved Mo increase. During self-mate pair sliding wear, the tribolayer transform from graphite to graphite+MoOx and then to MoOx. The cermets with 4 wt%. Mo show the best tribological properties, which shows a smooth and dense composite tribolayer formed mainly by graphite and MoOx.     

Mo、Ni含量与Ti(C,N)基金属陶瓷组织和性能之间的关系

本文研究了Mo、Ni含量对Ti（C，N）基金属陶瓷组织和性能的影响．结果表明，Mo、Ni含量对组织和性能有很大影响，化学成分决定了组织和性能．