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1.
Although titanium (Ti) alloys possess desirable properties such as specific strength, corrosion resistance and low density,
their low specific stiffness and wear resistance have restricted their widespread application. Recently, composite strategies
have provided means for overcoming these limitations. Titanium boride (TiBw) in-situ whisker reinforcements are currently recognized as one of the most compatible and effective reinforcements for Ti.
This paper provides an overview of recent activities in this evolving area of Ti–TiB composites, covering processing, properties
and potential applications. 相似文献
2.
Zhiqiang Zhang Ping Shen Yan Wang Yunpeng Dong Qichuan Jiang 《Journal of Materials Science》2007,42(19):8350-8356
Steel matrix composites locally reinforced by in situ TiC and TiB2 particulates were successfully fabricated using self-propagating high-temperature synthesis (SHS) in a Fe–Ti–B4C–C system during casting. The locally reinforced steel matrix composites consist of three distinct regions: (i) a TiC and
TiB2 particulate-reinforced region, (ii) a transition region, and (iii) a steel matrix region. The TiC and TiB2 particulates in the locally reinforced regions display a relatively uniform distribution, and their sizes decrease with the
increase in Fe content from 10 wt.% to 40 wt.%. The wear resistance of the locally reinforced region of the steel matrix composites
is much higher than that of the unreinforced steel matrix. 相似文献
3.
Tiesong Lin Minxuan Yang Peng He Chao Huang Feng Pan Yudong Huang 《Materials & Design》2011,32(8-9):4553-4558
Carbon–carbon composite (C–C composite) and TiB whiskers reinforced Ti–6Al–4V composite (TiBw/Ti–6Al–4V composite) were brazed by Cu–Ni + TiB2 composite filler. TiB2 powders have reacted with Ti which diffused from TiBw/Ti–6Al–4V composite, leading to formation of TiB whiskers in the brazing layer. The effects of TiB2 addition, brazing temperature, and holding time on microstructure and shear strength of the brazed joints were investigated. The results indicate that in situ synthesized TiB whiskers uniformly distributed in the joints, which not only provided reinforcing effects, but also lowered residual thermal stress of the joints. As for each brazing temperature or holding time, the joint shear strength brazed with Cu–Ni alloy was lower than that of the joints brazed with Cu–Ni + TiB2 alloy powder. The maximum shear strengths of the joints brazed with Cu–Ni + TiB2 alloy powder was 18.5 MPa with the brazing temperature of 1223 K for 10 min, which was 56% higher than that of the joints brazed with Cu–Ni alloy powder. 相似文献
4.
The TiC–TiB2/Al composites were fabricated by self-propagating high-temperature synthesis (SHS) from Al–Ti–B4C compacts. The addition of Al to the Ti–B4C reactants facilitates the ignition occurrence, lowers the reaction exothermicity, and modifies the resultant microstructure.
The maximum combustion temperature and combustion wave velocity decrease with the increase in the Al amount. The B4C particle size exerts a significant effect on the combustion wave velocity and the extent of the reaction, while that of
Ti has only a limited influence. The reaction products are primarily dependent on the B4C particle size and the Al content in the reactants. Desired products consisting of only the TiC, TiB2, and Al phases could be obtained by a cooperative control of the B4C particle size and the Al content. 相似文献
5.
The flake-forming behaviour of powders of molybdenum, niobium, nickel, BS 316 S 12, Ni–17Cr–6Al–0.6Y, iron, titanium and Ti–6Al–4V,
using a wet ball mill, was investigated. MgO–Al2O3–SiO2 (MAS) glass composites reinforced with these flaked particles were fabricated, and improvements in flexural strength evaluated.
The MAS glass composites reinforced with flaky metallic particles such as molybdenum, niobium, iron, nickel and Ni–17Cr–6Al–0.6Y,
showed an improvement. The effect of molybdenum particle size on the flake-forming behaviour of molybdenum, flexural strength
and fracture toughness of MAS glass/molybdenum composites, were investigated. The flake-forming behaviour shows a high degree
of dependence on molybdenum particle size and, upto a size of 32 μm, becomes conspicuous with increasing particle size. At
32 μm, the aspect ratio reaches a value of 17 and, above 32 μm, flake forming saturates. Fracture toughness is closely related
to flake-forming behaviour and the more marked the flake forming, the greater is the increase in fracture toughness. A composite
of MAS glass with flaky molybdenum particles has a greater improvement effect on fracture toughness than composites with SiC
whiskers, SiC platelets or ZrO2 particles. This is closely linked to plastic deformation of the flaky metallic particles at the crack tip at the time of
fracture.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
6.
Dan Zhu Mingxia Gao Shengcai Zhang Hongyan Wu Yi Pan Yongfeng Liu Hongge Pan Filipe J. Oliveira Joaquim M. Vieira 《Journal of Materials Science》2012,47(12):4921-4927
A high-strength SiC composite with SiC whiskers (SiCw) as reinforcement has been fabricated by liquid silicon infiltration (LSI) using pyrolyzed rice husks (RHs) as raw material.
RHs were coked and pyrolyzed subsequently at high temperature to obtain a mixture containing SiC whiskers, particles, and
amorphous carbon. The pyrolyzed RHs were then milled and modeled to preforms, which were then used to fabricate biomorphic
SiCw/SiC–Si composites by liquid silicon infiltration at 1,450, 1,550, and 1,600 °C, respectively. Dense composite with a density
of 3.0 g cm−3 was obtained at the infiltration temperature of 1,550 °C, which possesses superior mechanical properties compared with commercial
reaction-sintered SiC (RS-SiC). The Vickers hardness, flexure strength, elastic modulus, and fracture toughness of the biomorphic
SiCw/SiC–Si composite were 18.8 ± 0.6 GPa, 354 ± 2 GPa, 450 ± 40 MPa, and 3.5 ± 0.3 MPa m1/2, respectively. Whereas the composites obtained at the other two infiltration temperatures contain unreacted carbon and show
lower mechanical properties. The high flexure strength of the biomorphic composite infiltrated at 1,550 °C is attributed to
the dense structure and the reinforcement of the SiC whiskers. In addition, the fracture mechanism of the composite is also
discussed. 相似文献
7.
Magnesium matrix composites reinforced with a network of TiC and TiB2 compounds have been successfully synthesized via an in-situ reactive infiltration technique. In this process, the ceramic reinforcing phases, TiC and TiB2, were synthesized in-situ from the starting powders of Ti and B4C without any addition of a third metal powder such as Al. The molten AZ91 magnesium alloy infiltrates the preform of 3Ti–B4C by capillary forces. Furthermore, adding different weight percentages of MgH2 powder to the 3Ti–B4C preforms was used in an attempt to increase the Mg content in the fabricated composites. The results reveal a relatively uniform distribution of the reinforcing phases in the magnesium matrix with very small amounts of residual Ti, boron carbide and intermediate phases when they are fabricated at 900 °C for 1.5 h using a 3Ti–B4C preform with 70% relative density. On the other hand, after adding MgH2 to the 3Ti–B4C preform, TiCx and TiB2 formed completely without any residual intermediate phases with the formation of the ternary compound (Ti2AlC) at the expense of TiC. The percentage of reinforcing phases can be tailored by controlling the weight percentages of MgH2 powder added to the 3Ti–B4C preform. The results of the in-situ reaction mechanism investigation of the Ti–B4C and Mg–B4C systems show that the molten magnesium not only infiltrates through the 3Ti–B4C preform and thus densifies the fabricated composite as a matrix metal, but also acts as an intermediary making the reaction possible at a lower temperature than that required for solid-state reaction between Ti and B4C and accelerates the reaction rate. The investigation of the in-situ reaction mechanism with or without the addition of MgH2 powder to the 3Ti–B4C preforms reveals similar mechanisms. However, the presence of the MgH2 in the preform accelerates the reaction resulting in a shorter processing time for the same temperatures. 相似文献
8.
SiCw/BAS复合材料的显微结构及力学性能的研究 总被引:3,自引:0,他引:3
本文采用热压烧结法制备出致密的SiCw增强BAS玻璃陶瓷基复合材料.结果表明,BAS基体晶化后获得以钡长石为主晶相和莫来石为次晶相的复相BAS玻璃陶瓷.晶须的加入对BAS基体有显著的强韧化效果,加入30vol%SiCw可使材料的室温抗弯强度和断裂韧性分别由基体的156MPa和1.40MPa·m1/2提高到356MPa和4.06MPa·m1/2.TEM观察结果表明,晶须/基体界面结合良好,无界面反应物和非晶层的存在.断口形貌和压痕裂纹扩展路径的SEM观察结果表明,复合材料的主要增韧机制为裂纹偏转、晶须的拔出和桥接. 相似文献
9.
Tushar Borkar Sundeep Gopagoni Soumya Nag J. Y. Hwang Peter C. Collins Rajarshi Banerjee 《Journal of Materials Science》2012,47(20):7157-7166
In situ nitridation during laser deposition of titanium–molybdenum alloys from elemental powder blends has been achieved by introducing the reactive nitrogen gas during the deposition process. Thus, Ti–Mo–N alloys have been deposited using the laser engineered net shaping (LENSTM) process and resulted in the formation of a hard α(Ti,N) phase, exhibiting a dendritic morphology, distributed within a β(Ti–Mo) matrix with fine scale transformed α precipitates. Varying the composition of the Ar + N2 gas employed during laser deposition permits a systematic increase in the nitrogen content of the as-deposited Ti–Mo–N alloy. Interestingly, the addition of nitrogen, which stabilizes the α phase in Ti, changes the solidification pathway and the consequent sequence of phase evolution in these alloys. The nitrogen-enriched hcp α(Ti,N) phase has higher c/a ratio, exhibits an equiaxed morphology, and tends to form in clusters separated by ribs of the Mo-rich β phase. The Ti–Mo–N alloys also exhibit a substantial enhancement in microhardness due to the formation of this α(Ti,N) phase, combining it with the desirable properties of the β-Ti matrix, such as excellent ductility, toughness, and formability. 相似文献
10.
Guo -Dong Zhan Jian -Lin Shi Yang Zhou Yi -Zeng Zhang Ting -Rong Lai Tung -Sheng Yen 《Journal of Materials Science》1996,31(12):3237-3243
The microstructure and mechanical properties of hot-pressed yttria-stablized tetragonal zirconia polycrystals (Y-TZP) reinforced with up to 30 vol % SiC whiskers were investigated. The homogeneously dispersed and fully dense SiC whisker/Y-TZP composites were fabricated by wet-mixing the constitutents and uniaxially hot-pressing the resulting powder. The grain size of the matrix depended on the whisker volume fraction and the hot-pressing temperature. The significant increase of fracture toughness of about MPa m1/2 at 10 Vol % SiC and a small increase in strength were achieved by uniformly dispersing the whiskers in the Y-TZP matrix. Fracture surfaces revealed evidence of toughening by the mechanisms of crack deflection, pullout, and crack bridging by the whiskers and also a phase transformation of ZrO2. The observed increase in the fracture toughness of Y-TZP due to the addition of SiC whiskers was correlated with existing models of toughening mechanisms. Good agreement was achieved between the theoretical predictions and the experimental toughness values, obtained from the Y-TZP/SiCw composites. 相似文献
11.
12.
Feifei Wang Xiangqi Meng Naiheng Ma Jianming Xu Xianfeng Li Haowei Wang 《Journal of Materials Science》2012,47(7):3361-3366
The relationship between TiB2 volume fraction and fatigue crack growth behavior in the A356 alloy matrix composites reinforced with 3, 5.6, and 7.8 vol%
in situ TiB2 particles has been investigated. The mechanisms of crack propagation in the TiB2/A356 composites were also discussed. The results show that the 3 vol% TiB2/A356 composite has nearly the same crack growth behavior as the matrix alloy, while the 5.6 vol% TiB2/A356 composite exhibits a little bit faster crack growth rate. The 7.8 vol% TiB2/A356 composite presents the lowest resistance to crack growth, indicating that the crack growth is accelerated by increasing
TiB2 volume fraction. Fractographies reveal that an increase in TiB2 volume fraction results in a change from the formation of striation and slip to the failure of voids nucleation, growth,
and coalescence. Cracks tend to propagate within the matrix and avoid eutectic silicon and TiB2 particles in the intermediate ΔK region, while prefer to propagate along interfaces of eutectic silicon and TiB2 particles and link the fractured eutectic silicon particles in the near fractured ΔK region. Furthermore, the propensity for the separation of TiB2 increases with the increase in TiB2 volume fraction. The massive voids caused by fractured eutectic silicon and separated TiB2 particles propagate and coalesce, and then accelerates the crack growth in TiB2/A356 composites. 相似文献
13.
TiC–NiTi composites were produced by a technique combining self-propagating high-temperature synthesis (SHS) of elemental
powders of Ni, Ti, and C with densification by quasi-isostatic pressing (QIP). In order to create a one-step synthesis/densification
process, the Ti + Ni + C reactant material was surrounded in a bed of graphite and alumina particulate before initiation of
the combustion reaction. The sample was ignited within the particulate and subjected to a uniaxial load immediately after
passage of the combustion wave. The constitutive response, composition and resulting structures of the composites with varying
volume fractions of NiTi are characterized. Powder mixtures prepared anticipating the formation of stoichiometric TiC result
in the formation of composites with a eutectic matrix of Ni3Ti and NiTi. This titanium impoverishment of the matrix is consistent with the formation of nonstoichiometric TiC
x
during the combustion reaction. The Ni3Ti phase can be suppressed by anticipating the formation of TiC0.7 and adjusting the chemical content of the reactant mixture to include additional titanium. These cermets combine the high
hardness of the ceramic phase with the possible shape memory and superelastic effects of NiTi. 相似文献
14.
Ronghua Chen Weipeng Li Bochuan Li Chao Jiang 《Fatigue & Fracture of Engineering Materials & Structures》2023,46(1):17-31
It is crucial to obtain better fracture property of particle-reinforced metal matrix composites (PRMMCs) for application in structural parts. In this study, three-point bending tests are conducted on a TiB2-reinforced steel matrix composites (SMCs) with 9% and 13% TiB2 volume fractions to understand the effect of hot rolling and particle content on fracture toughness. Results show that increasing particle content has a negative effect on the fracture toughness of SCMs as a whole. Many microcracks induced by large-size particle fracture initiate in the front of crack tip and coalesce with one another are observed, thus accelerating the main crack propagation. However, hot rolling can effectively improve the fracture toughness and hardness of SMCs with two particle contents. Particle characteristics and matrix plasticity of the SMCs are optimized by hot rolling, which finally enhances the crack propagation resistance. The present work provides guiding suggestions for effectively improving fracture properties of PRMMCs. 相似文献
15.
The effect of Ti on the interfacial reactions, microstructural characteristics, and the related fluidity of Al–12%B4C composites has been investigated. Without Ti addition, B4C decomposed heavily during holding, and a large quantity of reaction-induced compounds, Al3BC and AlB2, was generated. When Ti was added, a TiB2 layer was built surrounding B4C particle surfaces, which acted as a diffusion barrier to separate B4C from liquid aluminum. Thus, the decomposition of B4C slowed down remarkably. The fluidity of the composite without Ti was the shortest of all composites and deteriorated quickly
during the holding time. The fluidity of the composite melt was improved significantly with increased Ti levels. The optimum
Ti level for the best fluidity results lied between 1.0 and 1.5%. The solid particle volume and the particle agglomeration
are the two main factors influencing the fluidity. 相似文献
16.
Ageing behaviour at 180 °C of 6061 aluminium alloy-SiCw composites, drawn from bars obtained in various extruded ratios, and 6061 aluminium alloy used as matrix, have been compared.
These materials were dissolved in a salt bath at 529 and 557 °C for 2 h, quenched in ice-water, and aged at 180 °C in an oil
bath for increasing periods. Ageing kinetics were studied with Brinell hardness measurements and differential scanning calorimetry
(DSC). Various samples of the composite, deriving from bars with Φ20, Φ35 and Φ50 mm in diameter, and 6061 aluminium alloy,
show the same ageing mechanism; however, the ageing rates results increased for composites. While 6061 aluminium alloy shows
its maximum hardness value after about 4–5 h at 180 °C, the 6061-SiCw composites reach theirs in 2–3 h. Moreover, for composites hardness abruptly decreases after 3 h, while aluminium alloy keeps
its maximum value for an ageing time as long as 6 h.
Thermal analysis allows us to put together a definite DSC trace for every microstructural state. The highest hardness values
are obtained as a result of the formation of a Guinier Preston (GP) needle-shaped zones, which progressively become more thermally
stable with protracted isothermal treatment at 180 °C. The different ageing process rates observed for composites and for
the 6061 alloy are correlated with the sizes of the reinforcements. Dimensional analysis of whiskers has been performed by
light scattering and scanning electron microscopy. Ordinarily the longer the average length of the whiskers in the samples,
the faster the ageing process. Higher temperatures are required for composite solutions than for 6061 alloy. On the other
hand, 6061-SiCw samples solutionized at higher temperature and then quenched sometimes show microcrack formation in the materials. 相似文献
17.
Composites of commercial-purity titanium reinforced with 10 and 20 vol % of SiC and TiB2 particulates were produced by powder blending and extrusion. Heat treatments were conducted on each of these composites. The thermal diffusivities of the composites were measured as a function of temperature using the laser flash technique. Thermal conductivities were inferred from these measurements, using a rule-of-mixtures assumption for the specific heats. It has been shown that, while an enhancement of the thermal conductivity is expected to arise from the presence of both types of reinforcement, this behaviour is in fact observed only with the Ti-TiB2 composites. The thermal conductivity of Ti-TiB2 composites is significantly greater than that of the unreinforced matrix and rises with increasing volume fraction of reinforcement. In contrast, the conductivities of the Ti-SiC composites were considerably lower than that of the unreinforced titanium and decreased with increasing volume fraction of SiC reinforcement. These results have been interpreted in terms of the thermal resistance of the reaction layers which exist between the matrix and two types of particulate reinforcements. The faster reaction kinetics between SiC and Ti gives rise to a thicker reaction layer for a given heat treatment than that between Ti and TiB2 and is also accompanied by a much larger volume change (– 4.6%). It is proposed that this volume decrease, giving rise to interfacial damage and a network of microcracks, is at least partly responsible for a high interfacial thermal resistance, reducing the conductivity of the Ti-SiC composite. These results indicate that TiB2 would be preferable to SiC as a reinforcement in Ti for situations where a high thermal conductivity would be beneficial. 相似文献
18.
BAS glass-ceramic composites reinforced with different volume fractions (0, 10, 20, 30, 40 vol%) of SiC whiskers were successfully fabricated by a hot-pressing method. The microstructure, whisker/matrix interface structure, phase constitution and mechanical properties of the composites have been systematically studied by means of SEM, TEM, XRD techniques as well as three-point bending tests. It was demonstrated that the incorporation of SiC whiskers could significantly increase the flexural strength and fracture toughness of BAS glass-ceramic matrixes. The celsian seeds can effectively promote the hexacelsian-to-celsian transformation in BaAl2Si2O8. The active Al2O3 added to the BAS matrix obviously reduced the amount of SiO2 in the matrix and formed needle-like mullite. The high temperature strengths of the composites were also investigated. 相似文献
19.
Si3N4 matrix composite was fabricated by hot pressing with 20% SiC whiskers coated with polycarbosilane (PCS). The preceramic polymer on the whiskers was pyrolysed during sintering to form a carbon-rich layer at the whisker/matrix interface. Mechanical properties were measured, and compared to those of the composites with whiskers purified with HCl and HF. Elastic modulus and bending strength of the composite with PCS-coated whiskers were lower than those of the composites with other whiskers. Fracture toughness was measured by single-edge notched beam (SENB) and single-edge precracked beam (SEPB) methods. The toughness, including crack-growth resistance measured by the SEPB method, increased from 7.2 MPam1/2 to 7.9 MPam1/2 by PCS-coating on the whisker, while the toughness measured by the SENB method decreased from 6.5 MPam1/2 to 5.7 MPam1/2. The layer derived from PCS facilitated debonding at the whisker/matrix interface and activated the wake-toughening. Optical microscopic observation of the crack propagation near the interface confirmed enhancement of interfacial debonding by the PCS-coating. 相似文献
20.
Feifei Wang Naiheng Ma Yugang Li Xianfeng Li Haowei Wang 《Journal of Materials Science》2011,46(15):5192-5196
The impact behavior of the in situ TiB2/Al composite was investigated at temperatures varying from −50 to 200 °C. The effects of the reinforcement, heat treatment
as well as temperature on the impact toughness and failure mechanism were discussed. Results showed that the impact toughness
of the composite decreases significantly due to the presence of the stiff TiB2 reinforcements. The precipitations caused by aging play the same role as TiB2 reinforcements, which constrain the deformation of the matrix and reduce the impact toughness. The TiB2/Al composite is more endurable in suffering the impact load at subzero and high temperatures compared to that at room temperature.
The fractography of the TiB2/Al composite is a cleavage-and-dimple morphology. The eutectic silicon is the preferred site for catastrophic cracking. There
is no cracking in the in situ TiB2 reinforcement because of the small size and near spherical shape. However, the “pulled-out” failure occurs for the TiB2 reinforcement, which is due to the relative weaker interfacial strength than the strength of reinforcement. 相似文献