共查询到20条相似文献,搜索用时 78 毫秒
1.
S. G. Warrier S. H. Chen S. K. Wu R. Y. Lin 《Metallurgical and Materials Transactions A》1996,27(5):1379-1394
Interfacial reactions between several ceramic fibers (SCS-0, SCS-6, and carbon fibers) and a liquid titanium-nickel-copper
alloy were investigated using electron microscopic analysis. Composite spec-imens were produced using a rapid infrared manufacturing
(RIM) process. In SCS-O/Ti alloy com-posites, SiC dissolved in the alloy. The main reaction product was discontinuous agglomerates
of titanium carbide which formed from the reaction between dissolved carbon and titanium. Polygonal precipitates of Ti5Si3, which are believed to have formed during cooling, were also noticed. Two distinct interface morphologies were observed in
these composites: uniform fronts caused by iso-thermal dissolution and scalloped fronts formed as a result of an accelerated
dissolution mechanism caused by localized heating. The presence of the accelerated dissolution mechanism suggests that SiC
fibers cannot be infiltrated with liquid titanium alloys without applying a coating. In the C/Ti system, carbon fibers reacted
with the liquid alloy to form a continuous layer of TixC1-x. Further growth of this layer occurred by the diffusion of carbon atoms across the reaction product. In SCS-6/Ti alloy composites,
free carbon present in the coating formed a discontinuous layer of Ti^C,^, whereas SiC particles dissolved in the alloy. Due
to channeled dissolution in the coating, the accel-erated dissolution mechanism was not observed in these composites. As a
result, the presence of the carbon-rich coating prevented degradation of the fibers. Although the coating present on SCS-6
fibers moderately retarded reactions in the SiC/Ti alloy composite system during infrared liquid infiltration, it is recommended
that the fibers be coated with pure carbon to effectively limit the attack of the fiber by molten titanium.
Formaly Postdoctoral Fellow, Department of Materials Science and Engineering, University of Cincinnati 相似文献
2.
A. Muthuchamy G. D. Janaki Ram V. Subramanya Sarma 《Transactions of the Indian Institute of Metals》2018,71(4):941-949
In the current research work, spark plasma consolidated beta-titanium alloy Ti–15V–3Cr–3Al–3Sn composites reinforced with SiC fibers (Sigma SM1240) were subjected to high temperatures (1173, 1223 and 1273 K) for different time periods (2.7, 11, 25 and 44 h) to investigate the kinetics of the chemical reactions at the fiber/matrix interface. Through microstructural studies and room temperature tensile tests, we have attempted to study the effect of the formed brittle reaction zone on the final mechanical properties of the composite. We have observed that, prior to the SiC fiber, the protective carbon coating reacts with the matrix and results in the formation of a reaction zone (predominantly TiC) at the fiber/matrix interface. The reaction zone propagates into the matrix with increase in time at the expense of the carbon coating, and finally ends with the onset of titanium silicide reaction. The reaction kinetics at the fiber/matrix interface was predominantly controlled by diffusion of carbon through the reaction zone and the activation energy for the same was calculated to be 149 kJ/mol. It was clear from the tensile test results that the mechanical properties of the composites do not earnestly decrease until the commencement of titanium silicide reaction. 相似文献
3.
采用Ti、Si、TiC粉末为原料,通过放电等离子反应烧结制备TiC-Ti<,3>SiC<,2>梯度功能材料.采用X射线衍射(XRD)、扫描电镜(SEM)和能谱分析(EDS)等手段,分析梯度材料的相组成和微观结构特征.结果表明,采用放电等离子烧结,升温速度为100℃/min时,在1 350℃保温15min、加压40MPa... 相似文献
4.
Synthesis mechanism of an Al-Ti-C grain refiner master alloy prepared by a new method 总被引:1,自引:0,他引:1
B. Q. Zhang L. Lu M. O. Lai H. S. Fang H. T. Ma J. G. Li 《Metallurgical and Materials Transactions A》2003,34(8):1727-1733
The mechanisms of in-situ synthesis of an Al-Ti-C grain-refiner master alloy, prepared by adding a powder mixture of potassium titanium fluoride and
carbon into an aluminum melt, have been systematically studied. It was found that vigorous reactions occurred at the initial
stage of reaction and then slowed down. After about 20 minutes, the reactions, which led the formation of blocky titanium
aluminides and submicron titanium carbides in the aluminum matrix, appeared to reach completion. Potassium titanium fluoride
reacted with aluminum and carbon at 724 °C and 736 °C, respectively, resulting in the formation of titanium aluminides and
titanium carbides in the aluminum matrix as well as in the formation of a low-melting-point slag of binary potassium aluminofluorides.
The reaction between potassium titanium fluoride and carbon is believed to be the predominant mechanism in the synthesis of
TiC by this method. 相似文献
5.
Metallurgical and Materials Transactions A - The interface structure of semicoherent titanium carbide (TiC) nanoparticles and incoherent micron-sized TiC precipitates in Fe–C–Ti alloy... 相似文献
6.
Specific features and regularities of reactions of titanium carbide alloyed over the sublattice of nonmetals (N, O) with the nickel melt are analyzed. It is established that the partial substitution of carbon in TiC by nitrogen decreases its dissolution rate in nickel and increases the degree of process incongruence (the transfer of carbon into the melt is preferential compared with titanium). The concentration dependence of the dissolution rate of TiCxNz in nickel changes its sign to the opposite one compared with approaching the system to equilibrium. Titanium carbonitride is not recrystallized through the nickel solution as the only phase, and mainly its carbide component is subjected to recrystallization. It is revealed that the partial substitution of carbon in TiC to oxygen increases its dissolution rate in nickel. The dissolution of oxycarbide TiC0.6O0.4 in nickel is accompanied by the gradual loss of its carbon until titanium monoxide is formed and by its further disproportionation. The peculiarity of the interaction mechanism of titanium oxycarbides with the nickel melt is determined by reaction [C] + [O] = CO↑ in the liquid phase. 相似文献
7.
Y. F. Yang H. Y. Wang J. G. Wang Q. C. Jiang 《Metallurgical and Materials Transactions A》2009,40(11):2514-2518
The ignition temperature of the thermal explosion reaction from the Ti-C system under air is much lower than that under Ar
atmosphere. The ignition mechanism for the Ti-C system under air is determined to be a mechanism of chemical oven, and the
reaction mechanism is dissolution, reaction, and precipitation. Namely, the heat generated from the oxidation and nitrification
of Ti and C can promote the melting of Ti inside the compact; subsequently, the carbon atoms dissolve into the Ti melt and
TiC precipitate. 相似文献
8.
T. N. Oskolkova E. A. Budovskikh V. F. Goryushkin 《Russian Journal of Non-Ferrous Metals》2014,55(2):196-200
The surface of the VK10KS hard alloy is hardened to 25 GPa; it is affected by pulsed plasma jets formed by the electric explosion of coal-graphite fibers and aluminum or titanium foil. It is established that intense hardening is inherent in alloys after electroexplosive alloying with titanium due to the formation of TiC and (Ti, W)C carbides in the surface layer. 相似文献
9.
碳含量对真空烧结钼合金的影响 总被引:2,自引:0,他引:2
通过在真空烧结TZM合金中添加不同比例的碳元素,研究了碳元素在不同温度下真空烧结时与其他元素的作用及其反应机理。结果表明:(1)添加碳元素的量要与钼合金未烧结坯料中的氧元素成一定比例,才能同时保证有效降低氧含量和合金中碳元素处于适中范围。(2)从热力学反应生成自由能计算结果来看,在Mo-Ti-Zr-C四元烧结体系中钛锆优先与碳反应生成(Ti,Zr)C;部分碳元素先与Mo反应生成Mo2C,在有Ti、Zr元素存在时,Mo2C将会与Ti、Zr发生Mo2C+2Ti=2TiC+Mo方式的反应,生成金属Mo和(Ti,Zr)C。 相似文献
10.
Interfacial segregation of Ti in the brazing of diamond grits onto a steel substrate using a Cu-Sn-Ti brazing alloy 总被引:1,自引:0,他引:1
Wen-Chung Li Shun-Tian Lin Cheng Liang 《Metallurgical and Materials Transactions A》2002,33(7):2163-2172
Diamond grits were brazed onto a steel substrate using a prealloyed Cu-10Sn-15Ti (wt pct) brazing alloy at 925 °C and 1050
°C. Due to the relatively high concentration of Ti in the brazing alloy, the braze matrix exhibited a composite structure,
composed of β-(Cu,Sn), a Cu-based solid solution, and various intermetallic compounds with different morphologies. The reaction of Ti with
diamond yielded a continuous TiC layer on the surfaces of the diamond grits. On top of the TiC growth front, an intermetallic
compound, composed of Sn and Ti, nucleated and grew into a randomly interwoven fine lacey structure. An interfacial structure
developed as the interwoven fine lacey phase was semicoherently bonded to the TiC layer, with the Cu-based braze matrix filling
its interstices. The thickness of such a composite layer was increased linearly with the square root of isothermal holding
time at 925 °C, complying with the law of a diffusion-controlled process. However, at 1050 °C, the segregation behavior of
Ti and Sn to the interfaces between the TiC layer and the braze matrix diminished, due to the increased solubility of Ti in
the Cu-based liquid phase. The enhanced dissolution of Ti in the Cu-based liquid phase at 1050 °C also caused the precipitation
of rod-like CuTi with an average diameter of about 0.2 μm during cooling. SnTi3 was the predominant intermetallic compound and existed in three different forms in the braze matrix. It existed as interconnected
grains of large size which either floated to the surface of the braze matrix or grew into faceted grains. It also exhibited
a nail-like structure with a mean diameter of about 1 μm for the rod section and a lamellar structure arising from a eutectic reaction during cooling. 相似文献
11.
Y. Choi M. E. Mullins K. Wijayatilleke J. K. Lee 《Metallurgical and Materials Transactions A》1992,23(9):2387-2392
Fine fibrous titanium carbide (TiC) was processed through the self-propagating high-temperature synthesis (SHS) method and
employed to fabricate aluminum matrix composites. Two consol-idation methods were investigated: (1) combustion synthesis of
TiC fiber/Al composites directly using titanium powders and carbon fibers ignited simultaneously with varying amounts of the
matrix metal powder and (2) combustion synthesis of TiC using titanium powders and carbon fibers followed by consolidation
into different amounts of the metal matrix powder, Al,via hot isostatic pressing (HIP). In the former method, when the amount of the Al in the matrix was increased, the maximum temperature
obtained by the combustion reaction decreased and the propagation of the synthesis reactions became difficult to maintain.
Preheating was required for the mixture of reactants with more than approximately 5 mole pct aluminum matrix powders in order
to ignite and maintain the propagation rate. Microstructural analysis of the products from the Al/C/Ti reaction without preheating
shows that small amounts of an aluminum carbide phase (AI4C3) are present. In the second method, following separation of the
individual fibers in the TiC product, dense composites containing the SHS products were obtained by HIP of a mixture of the
TiC fibers and Al powders. No ternary phase was formed during this procedure.
Formerly Graduate Research Assistant, Department of Chemical Engineering, Michigan Technological University, is with Particle
Technology, Inc., Hanover, MD 21076.
This paper is based on a presentation made in the symposium “Reaction Synthesis of Materials” presented during the TMS Annual
Meeting, New Orleans, LA, February 17–21, 1991, under the auspices of the TMS Powder Metallurgy Committee. 相似文献
12.
The anisotropic mechanical properties of a Ti matrix composite reinforced with SiC fibers 总被引:2,自引:0,他引:2
The anisotropic mechanical properties of a Ti alloy composite reinforced with SiC fibers have been investigated and rationalized
using analytical models. The appropriate material model for this composite involves the following features: an interface that
debonds and slides, a flaw insensitive ductile matrix, and high-strength elastic fibers subject to residual compressive stress
caused by thermal expansion mismatch. This, model is broadly consistent with the longitudinal, transverse, and shear properties
of the composite. 相似文献
13.
Erlin Zhang Songyan Zeng Qingchun Li Yang Bo Mingzhen Ma 《Metallurgical and Materials Transactions A》1999,30(4):1147-1151
The micromechanism and the macrokinetic process of synthesis TiC in preparing Al/TiC by direct reaction synthesis (DRS) have
been investigated in detail by observing the microstructure of the water-quenched preform by scanning electron microscopy
(SEM) and energy* dispersive X-ray (EDX) analysis. The results have shown that the micromechanism of reaction is a solution-precipitation
mechanism, in which carbon powders in the preform were surrounded by a Ti-rich Al-Ti-C melt layer and reacted with titanium
in the layer to synthesize TiC particles, and TiC precipitated from the layer and scattered over the alloy melt. The macrokinetic
model of reaction synthesis of TiC can be divided into four stages: heating and melting stage, initial reaction stage, complete
reaction stage, and cooling stage. In the end, a macrokinetic model has been set up based on the experimental results. 相似文献
14.
15.
I. V. Kud’ L. S. Likhoded L. I. Eremenko G. N. Makarenko V. B. Fedorus É. V. Prilutskii 《Powder Metallurgy and Metal Ceramics》2006,45(1-2):14-19
The structure and phase composition of the products of combined carbothermal reduction of titanium and niobium (tantalum)
oxides with an excess of carbon are studied. It is established that formation of solid solutions (Ti, Nb)C and (Ti, Ta)C occurs
through successive stages of synthesis of the individual carbides followed by dissolution of TiC in NbC (TaC). Excess of carbon
provides high dispersion of the reduction products and their purity with respect to oxygen. Features of solid solution (Ti,
Nb)C formation with interaction of niobium oxide and titanium carbide with an excess of carbon (12 mass%) are studied. Use
of fine-grained titanium carbide, pure with respect to oxygen, with excess carbon made it possible to reduce by 300 °C the
temperature for forming homogenous solid solution and to obtain powder with a particle size of less than 8 μm without grinding.
__________
Translated from Poroshkovaya Metallurgiya, Nos. 1–22(447), pp. 19–25, January–February, 2006. 相似文献
16.
采用燃烧波淬熄法,以Ti粉、Si粉和C粉为原料研究了层状可加工陶瓷Ti3SiC2在自蔓延高温合成(SHS)中的反应机理.淬熄试样中保留未反应区、反应区和已反应区,用扫描电子显微镜观察燃烧反应中显微组织的转变过程,用能谱仪分析各微区的成分变化,并通过差热分析(DSC-TGA)和XRD分析考察了从600℃到1500℃ Ti-C-Si系统的反应合成过程和相形成规律.结果表明:层状可加工陶瓷Ti3SiC2自蔓延高温合成的机理为溶解-析出机制,Ti粉与Si粉的固态扩散导致低熔点Ti-Si溶液形成,Ti、Si、C粉粒逐渐向Ti-Si溶液中溶解,当溶液中的Ti、Si、C浓度饱和时,从中析出TiC、SiC颗粒,最后形成最终产物Ti3SiC2. 相似文献
17.
Experiments on the reaction between graphite and liquid Fe-Ti alloys were performed with a mirror furnace on board an airplane
during parabolic flights. Small Fe-Ti alloy samples were melted in contact with graphite and held for some seconds at a temperature
of 1550 °C. The samples were melted and solidified during a microgravity period. Carbon and titanium atoms reacted in the
melt and titanium carbides were formed. In the experiments, a precipitation zone with faceted titanium carbide crystals dispersed
in high carbon Fe-C-Ti alloy matrix was obtained near the graphite/alloy interface. The thicknesses of the carbide precipitation
zones were measured and effects of alloy composition on the growth rates of the carbide zones were revealed by experiments
and calculations. It was shown that the process was controlled by the diffusion of titanium in the liquid at low titanium
concentrations and by diffusion of carbon through the precipitation layer at high titanium concentrations in the melt. Supersaturation
of the carbide in front of the reaction interface was predicted from the calculations. The analysis showed that homogeneous
nucleation of titanium carbide can readily occur in the alloys. Carbide morphologies were analyzed, and the mechanisms which
lead to their formation are discussed. 相似文献
18.
The mechanism and kinetics of the reduction-carbidization of titanium oxide by calcium hydride and carbide (hydride-calcium method) are studied. This process provides the production of single-crystal powdered titanium carbide. Theoretical analysis and experimental methods is found that the mechanism of the formation of TiC forms is staged and includes two sequential reactions: TiO2 + 2CaH2 = Ti + 2CaO + 2H2↑ and Ti + C = TiC. It is revealed that the formation of titanium carbide proceeds in a calcium melt by the dissolution of titanium and graphite in it with the subsequent crystallization of the TiC particles from the melt. It is noted that the kinetics of the process in the range t = 900?1200°C depends on the temperature and time of isothermal holding. At t > 1100 °C, its abrupt activization is observed. This is due to an increase in the amount of melt based on calcium and the enhancement of the solubility of titanium and carbon in it, which leads to the acceleration of reactions of reduction of titanium oxide to titanium and to the synthesis of titanium carbide. The optimum technological parameters of the process (temperature, time of isothermal holding, and conditions of the calculation of the charge) are determined. It is shown that titanium carbide obtained by this technology is homogeneous and has the content close to stoichiometric one, specifically, TiC1.0. 相似文献
19.
研究了500~670 ℃回火热处理对轧制钛/钢复合板界面组织与性能的影响,以期为复合板热加工的工艺参数制定提供指导。对轧态和回火态的钛/钢复合板进行了拉伸、冲击和剪切试验测试,并利用光学显微镜、扫描电镜、X射线衍射等研究手段表征了复合板的界面组织、剪切断口形貌及断口反应相。结果表明,回火热处理后,钛/钢复合板的剪切性能降低,随着回火温度的升高,剪切强度呈现下降趋势。轧态和回火态复合板界面反应相均为β Ti和TiC,其中TiC反应相的厚度随着回火温度的升高呈现增厚趋势。TiC脆性相厚度的增加导致了复合板剪切强度的下降,且使得剪切断口呈现脆性断裂倾向增大,撕裂特征减弱,呈现出明显的平滑断裂特征。 相似文献
20.
P. K. Liaw E. S. Diaz K. T. Chiang D. H. Loh 《Metallurgical and Materials Transactions A》1995,26(12):3225-3247
Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous
silicon carbide (SiC) fibers. The titanium composites had an eightply (0, 90, +45, -45 deg) symmetric layup. Fatigue life
was found to be sensitive to fiber layup sequence. Increasing the test temperature from 24 °C to 427 °C decreased fatigue
life. Interface debonding and matrix and fiber fracture were characteristic of tensile behavior regardless of test temperature.
In the tensile fracture process, interface debonding between SiC and the graphite coating and between the graphite coating
and the carbon core could occur. A greater amount of coating degradation at 427 °C than at 24 °C reduced the Ti/SiC interface
bonding integrity, which resulted in lower tensile properties at 427 °C. During tensile testing, a crack could initiate from
the debonded Ti/SiC interface and extend to the debonded interface of the neighboring fiber. The crack tended to propagate
through the matrix and the interface. Dimpled fracture was the prime mode of matrix fracture. During fatigue testing, four
stages of flexural deflection behavior were observed. The deflection at stage I increased slightly with fatigue cycling, while
that at stage II increased significantly with cycling. Interestingly, the deflection at stage III increased negligibly with
fatigue cycling. Stage IV was associated with final failure, and the deflection increased abruptly. Interface debonding, matrix
cracking, and fiber bridging were identified as the prime modes of fatigue mechanisms. To a lesser extent, fiber fracture
was observed during fatigue. However, fiber fracture was believed to occur near the final stage of fatigue failure. In fatigued
specimens, facet-type fracture appearance was characteristic of matrix fracture morphology. Theoretical modeling of the fatigue
behavior of Ti/SCS-6 composites is presented in Part II of this series of articles.
This article is based on a presentation made in the symposium entitled “Creep and Fatigue in Metal Matrix Composites” at the
1994 TMS/ASM Spring meeting, held February 28–March 3, 1994, in San Francisco, California, under the auspices of the Joint
TMS-SMD/ASM-MSD Composite Materials Committee. 相似文献