燃烧合成/准热等静压TiC-Fe基复合材料耐磨损性能的研究

利用燃烧合成结合准热等静压技术(SHS/PHIP)原位合成了TiC颗粒增强铁基复合材料。利用SEM,XRD研究了复合材料的相组成和显微组织。结果表明:该复合材料由TiC增强颗粒和金属Fe粘结相组成,组织较为致密,球形的TiC颗粒相被包围在近于立体网状结构的Fe粘结相中。TiC颗粒相和金属Fe粘结相的界面结合良好。在橡胶轮式磨损试验条件下,TiC颗粒增强铁基复合材料表现出良好的耐磨性能。其磨损机制主要是磨粒磨损和少量硬质相脱落。     

微波烧结原位合成(Ti_5Si_3+TiC)/TC4复合材料组织性能研究

通过Ti-SiC反应体系,选择粒径为45μm的基体TC4,5μm的增强相SiC(质量分数为5%和10%),经过低能球磨混粉后,微波烧结原位合成颗粒增强钛基复合材料。采用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱仪(EDS)对制备的钛基复合材料进行组织结构分析,并对钛基复合材料的致密度、显微硬度、压缩强度、抗拉强度、耐磨性和抗氧化性进行测试研究。结果表明,钛基复合材料主要由增强相TiC,Ti_5Si_3及基体Ti_3种物相组成。TiC呈颗粒状,有明显的棱角,而Ti_5Si_3呈熔融状颗粒,但是颗粒没有明显的棱角,增强相呈准连续网状分布,随着SiC含量的增加,网状结构不清晰,部分增强相团聚在一起。复合材料的相对密度、显微硬度和压缩强度随SiC含量的增加而增加,分别达到98.76%,HV729和2058MPa,但是复合材料的室温拉伸强度随SiC含量增加而降低。引入增强相后,复合材料的抗氧化性和耐磨性均高于基体,且耐磨性和抗氧化性随SiC含量增加而增加,其室温磨损机制主要为粘着磨损。     

TiC粒子增强钛基复合材料的显微组织与性能研究

探讨了添加粒子的形态对熔铸法制备的TiC粒子增强钛基复合材料力学性能与显微组织的影响。研究采用的TiC粒子增强的钛基复合材料是用预处理熔炼法 (PTMP)工艺制备的。将二次真空自耗电弧熔炼的铸锭用常规方法锻造成Φ13mm左右的棒材 ,在其上切取拉伸试样和蠕变试样 ,在 80 0～ 10 5 0℃温度范围内热处理 1h ,空冷。测试复合材料的室温和高温拉伸以及蠕变性能。研究结果表明 ,TiC粒子在基体分布均匀 ,添加尺寸为 5 μm以下的球形或近似球形TiC粒子时 ,粒子增强的钛基复合材料的综合性能优异 ,具有良好的热强性与室温塑性匹配 ,直至 65 0℃ ,复合材料仍具有良好的综合机械性能     

(GNPs+B)/TC4复合材料组织和硬度研究

采用放电等离子烧结技术(SPS),制备石墨烯纳米片(GNPs)、硼粉(B)增强TC4钛基复合材料(TiMCs).利用扫描电镜、拉曼光谱对混合粉末以及烧结后材料的组织进行了研究.利用维氏硬度仪对复合材料进行硬度测试.结果表明:GNPs和B与基体原位反应生成TiC颗粒(TiCp)和TiB晶须(TiBw)构成的非连续网状结构...     

不连续增强钛基复合材料的研究进展

不连续增强相能有效改善钛基体的力学性能，提高钛基体的耐磨性、高温强度和抗氧化性，拓宽了钛合金的应用领域。陶瓷增强相具有硬度高、耐磨性好、热稳定、成本低廉等优点，成为不连续增强钛基复合材料的首选增强相，其中使用最为广泛的是TiC颗粒和TiB纤维。纳米碳材料因具有高弹性模量以及高抗拉强度等优异性能，可有效改善复合材料的强度、塑性，被用来制备高比强度的钛基复合材料，近年来成为最具潜力增强体材料。本文从增强体材料的选择出发，归纳总结了近十年不连续增强钛基复合材料的研究进展，综述了不同增强体材料对钛基体组织与力学性能的影响以及强化机理，提出进一步的研究方向，为提高钛基复合材料的整体性能和扩大其应用范围提供一定的依据。     

原位反应合成致密Al2O3p-TiCp/Al复合材料

采用高能球磨细化晶粒、原位反应合成及热压技术制备了致密的Al2 O3 p TiCp/Al复合材料 ,并用XRD、SEM、以及EDAX等手段分析了复合材料的相组成、显微组织。结果表明 :Al TiO2 C三元体系在热压反应烧结后 ,可制得致密度较高的Al2 O3p TiCp/Al原位复合材料 ,其显微组织中Al2 O3 和TiC颗粒尺寸为 1μm左右 ,分布均匀。高能球磨有利于增强颗粒细化及弥散分布和反应。     

铜与氧化石墨烯协同增强钛基复合材料显微组织及性能研究

通过放电等离子烧结(SPS)技术制备铜(Cu)和氧化石墨烯(GO)协同增强的钛基复合材料(GO/Cu/TA1),研究了氧化石墨烯和Cu元素对钛基复合材料组织、硬度及拉伸性能的影响。结果表明：GO/Cu/TA1复合材料晶内析出金属间化合物Ti_2Cu相,晶界处存在非连续分布的TiC颗粒。复合材料的抗拉强度和屈服强度较TA1纯钛分别提高了66%和82%,显微硬度提升了58.4%,且延伸率保持在15%左右。硬度及强度的提升归因于晶界处分布的TiC颗粒与晶内析出的金属间化合物Ti_2Cu相的协同强化作用。     

发动机用石墨烯表面镀Cu增强钛基复合材料的制备及力学性能

通过微波烧结法制备石墨烯(GNPs)表面镀Cu增强钛基(Ti6Al4V)复合材料,探讨石墨烯表面镀Cu后对钛基复合材料显微组织和力学性能的影响。结果表明:石墨烯表面成功镀覆一层较均匀分布的Cu颗粒;石墨烯与基体Ti界面反应严重,容易生成粒径为2~5μm的TiC,石墨烯表面镀Cu后,界面反应产生的TiC含量更多,同时生成了Ti_2Cu相;相比于单纯外加石墨烯,石墨烯表面镀Cu后,提高了复合材料的力学性能,其相对密度、显微硬度、抗压强度分别达到95.48%、468 HV_(0.1)、1 406 MPa;室温磨损机制由基体(Ti6Al4V)的磨粒磨损转变为GNPs-Cu/Ti6Al4V复合材料的黏着磨损。     

加温拉伸条件TiCp—AlNp／Al复合材料组织与力学性能

主要研究了加温拉伸下TiCp—AlNp/Al复合材料组织与力学性能,具体探讨了温度对此复合材料屈服强度的影响,并结合不同温度拉伸断口的形貌来讨论复合材料的断裂机制;基于实验数据和电镜观察,讨论了复合材料塑性与拉伸温度的关系,分析了自生相颗粒TiC和AIN在加温拉伸的过程中强化基体的微观机制。     

颗粒增强钛基复合材料缓进深切磨削加工研究

正颗粒增强钛基复合材料(以下简称PTMCs)是以钛合金(Ti-6Al-4V)为基体、以TiC颗粒等为增强相的金属基复合材料。可以在极大改善钛合金基体材料比强度、比模量的同时,拥有良好的延展性与韧性,具有更好的高温性能、耐腐蚀性能和抗疲劳性     

TiC含量对激光熔覆TiC增强双相不锈钢复合涂层性能的影响

采用激光熔覆技术在40 Cr Ni Mo基材上制备了TiC增强双相不锈钢复合熔覆层,熔覆层物相主要由奥氏体、马氏体、M₇C₃型碳化物和TiC组成。其中M₇C₃型碳化物主要包括Fe₇C₃、Cr₇C₃或者(Fe、Cr)₇C₃三种,TiC按尺寸可分为熔解后析出的微米级TiC以及粗大的未熔TiC颗粒。析出的TiC颗粒为方块状,随着TiC添加量增加,呈花瓣状长大。未熔TiC颗粒与基材形成了扩散界面,具有很好的界面结合性。当加入30 wt.%TiC时,熔覆层具有最好的耐磨性,硬度可达55.26 HRC,磨损体积为2.54×10^-2 mm³,耐磨性是基材的3.37倍。     

Fabrication of TiC/Fe–Ni cermet coatings by reactive thermal spraying of Fe–Ti–Ni–C composite powder

Abstract

A mixture of ferrotitanium, nickel powders and sucrose was heated with an intention of carbonising the sucrose. The tiny ferrotitanium, nickel particles are bound by the carbon obtained from pyrolysis of the sucrose to form a unique structure of Fe–Ti–Ni–C composite powder for reactive thermal spraying. The carbon is a reactive constituent as well as the binder in the composite powder. TiC/Fe–Ni cermet coating was prepared by reactive plasma spraying of this powder. A mass of TiC particles were in situ synthesised and uniformly distributed in the Fe–Ni alloy matrix without residuals of raw materials in the coating. The coating is consisted of two different areas: one is the composite area, where lots of spherical fine TiC particles (100–500 nm) are homogeneously distributed within the Fe–Ni alloy matrix; the other is a small fraction of TiC accumulation. The volume fraction of composite area is >87%.     

Evaluation of Centrifugal Casting Process Parameters for In Situ Fabricated Functionally Gradient Fe-TiC Composite

A gradient Fe-TiC composite was successfully produced via combination of in situ reaction with centrifugal casting techniques. Additionally, some of the effective parameters of the centrifugal casting process have been studied. Cast iron and ferrotitanium, which were used as raw materials, were melted using a high-frequency induction furnace coupled with centrifugal equipment. The microstructure and phase characterization of the fabricated composite was studied by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results show that the production of a pearlite matrix composite reinforced by TiC particles is feasible. The distribution of TiC in the pearlitic matrix is completely uneven as a result of density difference between molten medium and TiC in the centrifugal casting process.     

钢与TiC颗粒之间界面润湿性分析

 TiC粒子具有高硬度、高熔点和高热力学稳定等特点,以TiC粒子作为增强相具有提高钢基体强度、耐高温和耐磨损等性能的潜力,近年来相关钢种的开发受到越来越多的关注。增强相颗粒与钢基体之间良好的润湿性是提高界面结合强度、防止颗粒在磨损过程中脱落的关键。因此,为了明确TiC粒子与钢基体之间的润湿程度,指导以TiC为增强相的耐磨钢的开发,采用高温座滴法观察钢液滴在TiC基片上的铺展行为,采用电子探针分析钢与TiC颗粒之间微区的元素分布,并结合热力学计算,探究高温下钢液与TiC之间界面润湿行为。结果表明,钢液与TiC之间的润湿性很好,在升温以及保温过程,钢样熔化后能通过TiC基片中的微孔快速渗入到基体内部,表现为钢样向下“坍塌”,直至钢样从观察窗口中完全消失。钢液进入TiC基片内部的同时,钢中氮元素向周围TiC相扩散。电镜分析表明钢液与TiC颗粒界面上没有产生新的相。TiC(TiN)与铁组成的二元相图表明,与TiN相比,TiC在钢液中有较大的溶解度,这解释了TiC-钢系统比TiN-钢系统润湿性好的原因。钢液与TiC颗粒之间的界面润湿性好且不发生化学反应,保证了TiC颗粒可作为增强相来提高钢的耐磨性能。为TiC颗粒与高钛钢之间的润湿性研究提供借鉴,为高钛耐磨钢成分的设计提供理论指导。     

X-ray diffraction study of the dependence of the fine TiC structure on dispersion of hardening phase particles

The special features of the fine structure of the TiC—based composite were studied by the methods of X-ray diffraction, the methods of local X-ray spectrum analysis and optical microscopy. The correlation between the thin TiC structure parameter values and dispersion of TiN phase particles was established.     

TiB_2和TiC复合熔敷棒的制备及电火花涂层特性

利用粉末冶金法制备TiB2和TiC复合材料熔敷棒,并通过电火花沉积在点焊镀锌钢板用电极的表面制备TiB2和TiC复合涂层。利用SEM和XRD分析涂层的微观结构和物相,运用点焊实验测试涂层电极的使用寿命。结果表明:复合材料熔敷棒中TiB2和TiC颗粒细小均匀,电火花涂层致密无分层,涂层物相为Cu、TiB2和TiC;Cu从基体扩散到涂层表面,涂层表面Cu含量(原子分数)达到28%,过渡层出现Cu和Ti的梯度分布,涂层与基体间为牢固的冶金结合;复合涂层存在少量裂纹,其显微硬度达到850HV,高于TiB2涂层和TiC涂层硬度;点焊时电极头部的平均磨损率大大降低,电极的点焊寿命比无涂层电极提高4倍。     

NiTi and NiTi-TiC composites: Part IV. Neutron diffraction study of twinning and shape-memory recovery

Neutron diffraction measurements of internal elastic strains and crystallographic orientation were performed during compressive deformation of martensitic NiTi containing 0 vol pct and 20 vol pct TiC particles. For bulk NiTi, some twinning takes place upon initial loading below the apparent yield stress, resulting in a low apparent Young's modulus; for reinforced NiTi, the elastic mismatch from the stiff particles enhances this effect. However, elastic load transfer between matrix and reinforcement takes place above and below the composite apparent yield stress, in good agreement with continuum mechanics predictions. Macroscopic plastic deformation occurs by matrix twinning, whereby (1 0 0) planes tend to align perpendicular to the stress axis. The elastic TiC particles do not alter the overall twinning behavior, indicating that the mismatch stresses associated with NiTi plastic deformation are fully relaxed by localized twinning at the interface between the matrix and the reinforcement. For both bulk and reinforced NiTi, partial reverse twinning takes place upon unloading, as indicated by a Bauschinger effect followed by rubberlike behavior, resulting in very low residual stresses in the unloaded condition. Shape-memory heat treatment leads to further recovery of the preferred orientation and very low residual stresses, as a result of self-accommodation during the phase transformations. It is concluded that, except for elastic load transfer, the thermal, transformation, and plastic mismatches resulting from the TiC particles are efficiently canceled by matrix twinning, in contrast to metal matrix composites deforming by slip.     

Al-TiC composites In Situ-processed by ingot metallurgy and rapid solidification technology: Part I. Microstructural evolution

The present work was undertaken to highlight a novel in situ process in which traditional ingot metallurgy plus rapid solidification techniques were used to produce Al-TiC composites with refined microstructures and enhanced dispersion hardening of the reinforcing phases. Microstructures of the experimental materials were comprehensively characterized by optical microscopy, electron microscopy, and X-ray diffraction. The results show that the in situ-synthesized TiC particles possess a face-centered cubic crystal structure with an atomic composition of TiC_0.8 and a lattice parameter of 0.431 nm. The typical ingot metallurgy microstructures exhibit aggregates of TiC particles segregated generally at the α-Al subgrain or grain boundaries and consisting of fine particles of 0.2 to 1.0 μm in size. The rapidly solidified microstructures formed under certain thermal history conditions contained a uniform, fine-scale dispersion of TiC phase particles with a size range of 40 to 80 nm in an α-Al supersaturated matrix of 0.30 to 0.85 μm in grain size. These dispersed TiC particles generally have a semicoherent relationship with the α-Al matrix. Based on the experimental results, a comprehensive kinetic mechanism of in situ TiC synthesis, which includes a solid-liquid interface reaction between the carbon particles and the Al melt and multiple nucleation and growth of TiC from the Al melt, was proposed. Then, the evolution of the aggregate TiC particles in a superheated melt before rapid solidification, i.e., dissolution, nucleation, and growth of the regenerated TiC dispersed particles, was analyzed. Furthermore, the behavior of rapid solidification kinetics, the nucleation of α-Al on TiC-dispersed particles, and the interaction between TiC particles and the solidification front were documented experimentally and theoretically. These studies provided the theoretical criteria and an experimental basis for the optimum design of this kind of composite.     

Microstructure and mechanical behavior of the NiAl-TiC In situ composite

The microstructure, interfaces, and mechanical properties of NiAl-matrix composites reinforced by 0 and 20 vol pct TiC particles have been examined. The composites were prepared by the hot-pressaided exothermic synthesis (HPES) technique. Portions of the HPES-processed samples were hot isostatically pressed (“hipped”) at 1165 °C/150 MPa for 4 hours or annealed at 1400 °C for 48 hours. In the as-fabricated state, TiC particles were generally polygonal and faceted, and the interfaces between TiC and NiAl were atomically flat, sharp, and generally free from any interfacial phase. At least two orientation relationships between TiC and NiAl were observed. In some cases, thin amorphous layers existed at NiAl/TiC interfaces. After “Hipping,” the TiC particles tended to become round and the TiC/NiAl interfaces became overlapped. Annealing at 1400 °C for 48 hours did not affect the microstructure or the interfacial structure of the composite in most cases. The compressive yield strengths (YSs) from room temperature to 1100 °C of the composite were considerably higher than that of the monolithic NiAl. At 980 °C, the tensile YS of the composite was approximately 3 times that of the monolithic NiAl. In addition, the ambient fracture toughness of the composite was 50 pct higher than that of the monolithic NiAl.