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1.
《Composites Part A》2002,33(3):439-444
In situ TiB2 particulate reinforced near eutectic Al–Si alloy composites fabricated by the melt reaction composing (MRC) methods have been investigated. It has been shown that minute TiB2 particles (less than 1 μm) uniformly distribute in the eutectic structure and they are interlaced with the coralline-like eutectic Si, while there are very few TiB2 particles in α-Al. It has been also shown that in situ TiB2 particles can enhance the tensile strength of the Al–Si alloy matrix. The strengthening effect increases with increasing TiB2 content. The ultimate tensile strength (UTS) at room temperature of as-cast 6%TiB2/Al–Si–Mg composite is 296 MPa, that is a 14.7% increase over the matrix, and its elongation at fracture is 5.5%. After heat-treatment (T6), the UTS of the composites reaches 384 MPa. The strengthening mechanism has been discussed. 相似文献
2.
Liqiang Wang Weijie Lu Jining Qin Fan Zhang Di Zhang 《Materials science & engineering. C, Materials for biological applications》2009,29(6):1897-1900
A novel (TiB + La2O3)/Ti-alloy composite was In situ synthesized through homogeneously melting in a non-consumable vacuum arc remelting furnace. Ti–35Nb–2Ta–3Zr β titanium alloy was chosen as the matrix Ti-alloy and different mass fractions of LaB6 were chosen as additions. Microstructure observations were examined by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The phase analysis was identified by X-ray diffraction (XRD). Largest ultimate tensile strength around 580 MPa and highest elongation around 30% is obtained in 0.1% LaB6-additioned specimen. The appearance of too many La2O3 particles and the reduction of oxygen in the matrix alloy also attribute much to the strength and plasticity of (TiB + La2O3)/Ti composites. Lower ultimate tensile strength around 526 MPa is obtained in 0.5% LaB6-additioned specimen. 相似文献
3.
In this paper, a practical and cost‐effective processing route, in situ reactive infiltration technique, was utilized to fabricate magnesium matrix composites reinforced with a network of TiC–TiB2 particulates. These ceramic reinforcement phases were synthesized in situ from Ti and B4C powders without any addition of a third metal powder such as Al. The molten Mg alloy infiltrates the preform of (Tip + B4Cp) by capillary forces. The microstructure of the composites was investigated using scanning electron microscope (SEM)/energy dispersive X‐ray spectroscopy (EDS). The compression behavior of the composites processed at different conditions was investigated. Also, the flexural strength behavior was assessed through the four‐point‐bending test at room temperature. Microstructural characterization of the (TiB2–TiC)/AZ91D composite processed at 900 °C for 1.5 h shows a relatively uniform distribution of TiB2 and TiC particulates in the matrix material resulting in the highest compressive strength and Young's modulus. Compared with those of the unreinforced AZ91D Mg alloy, the elastic modulus, flexural and compressive strengths of the composite are greatly improved. In contrast, the ductility is lower than that of the unreinforced AZ91D Mg alloy. However, this lower ductility was improved by the addition of MgH2 powder in the preform. Secondary scanning electron microscopy was used to investigate the fracture surfaces after the flexural strength test. The composites show signs of mixed fracture; cleavage regions and some dimpling. In addition, microcracks observed in the matrix show that the failure might have initiated in the matrix rather than from the reinforcing particulates. 相似文献
4.
Si3N4/Al–Mg composites based on Al–Mg alloy reinforced by ceramic interpenetrating network structure were fabricated via pressureless infiltration technology. Infiltration temperature and infiltration time are the key parameters distinctly effecting on infiltration processes. Moreover, the increasing of Mg content (2–8 wt.%) resulted in an increased amount of infiltration. Microstructural characterization of the composites reveals a special topology of skeleton and good integrity of metal/ceramic interface. The presence of second reinforced phase results in a significant increase in 0.2% offset yield and ultimate tensile strength of composites materials. However, when the volume fraction of reinforcement is large than 6%, there are a distinctly reduction of strength. The presence of additional secondary brittle phase in matrix results in the reduction in ductility and increase in hardness of 3-DNRMMCs. The failure features as cracking and void in reinforcement, interface cracking and interface debonding as well as matrix damage result in the decreases of fracture toughness. With the increases of volume fraction of reinforcement, 3-DRMMC exhibits excellent wear-resistance property. 相似文献
5.
In situ fabrication of aluminum matrix composites (AMCs) has gathered widespread attention of researchers due to inherent advantages over ex situ methods. Aluminum alloy AA7075 reinforced with various amounts (0, 3, 6 and 9 wt.%) of TiB2 particles were prepared by the in situ reaction of inorganic salts such as K2TiF6 and KBF4 to molten aluminum. X-ray diffraction patterns of the prepared AMCs clearly revealed the formation of TiB2 particles without the presence of any other intermetallic compounds. The microstructures of the AMCs were studied using optical and scanning electron microscopy. The in situ formed TiB2 particles were characterized with uniform distribution, clear interface, good bonding and various shapes such as cubic, spherical and hexagonal. The formation of TiB2 particles enhanced the microhardness and ultimate tensile strength (UTS) of the AMCs. 相似文献
6.
The microstructural and mechanical behavior of hybrid metal matrix composite based on aluminum alloy 6082-T6 reinforced with silicon carbide (SiC) and boron carbide (B4C) particles was investigated. For this purpose, the hybrid composites were fabricated using conventional stir casting process by varying weight percentages of 5, 10, 15, and 20?wt% of (SiC?+?B4C) mixture. Dispersion of the reinforced particles was studied with x-ray diffraction and scanning electron microscopy analyses. Mechanical properties such as micro-hardness, impact strength, ultimate tensile strength, percentage elongation, density, and porosity were investigated on hybrid composites at room temperature. The results revealed that the increase in weight percentage of (SiC?+?B4C) mixture gives superior hardness and tensile strength with slight decrease in percentage elongation. However, some reduction in both hardness and tensile strength was observed in hybrid composites with 20?wt% of (SiC?+?B4C) mixture. As compared to the un-reinforced alloy, the improvement in hardness and tensile strength for hybrid composites was found to be 10% and 21%, respectively. Reduction in impact strength and density with increase in porosity was also reported with the addition of reinforcement. 相似文献
7.
In situ TiB2 reinforced Al 6063 composites have been successfully synthesized through the chemical reaction between Al–10%Ti and Al–3%B master alloys in the Al 6063 alloy using liquid metallurgy route. The amount of TiB2 formed in the composite is estimated using gravimetric analysis. Mechanical properties in terms of microhardness, ultimate tensile strength and modulus of elasticity have been improved by 21%, 47% and 65% respectively in comparison with matrix alloy. Further, ductility in terms of percentage elongation of the composites was found to increase by about 368% when compared with the matrix alloy. The improvement in ductility may be associated with the grain refinement of the composite with an increase in the content of Al–3%B master alloy. 相似文献
8.
Yonggang Yang Xizhou Kai Ran Tao Min Wang Houshang Yin 《Materials Science & Technology》2018,34(11):1323-1332
The in situ (TiB2?+?ZrB2)/7055Al composites were successfully fabricated from the 7055Al-K2TiF6-K2ZrF6-KBF4 system by a direct melt reaction method. Microstructural observations revealed that the nanoparticles were distributed relatively uniformly in the aluminium matrix, and that these nanoparticles exhibit various shapes such as spherical, hexagonal and cubic, with an average size of about 80?nm. Mechanical property testing showed that the strength and Young’s modulus of the composites increased significantly in comparison to the 7055 matrix alloy. The maximum ultimate tensile strength was approximately 361?MPa, with a yield strength of 323?MPa and an elongation of 3.6%, which constitute increases of 31.3%, 28.7% and 44% when compared to the 7055Al alloy, respectively. The strengthening mechanisms of the fabricated composites were also discussed. 相似文献
9.
《Materials Science & Technology》2013,29(11):1233-1240
AbstractAluminium matrix composites reinforced with submicrometre and nanosize Al2O3 particles were successfully manufactured in the form of sheets through eight cycles of accumulative roll bonding process. The mechanical properties of the produced composite are compared with accumulative roll bonded commercially pure aluminium. It is shown that only 1 vol.-% of submicrometre or nanosize alumina particles as reinforcement in the structure can significantly improve the yield and ultimate tensile strengths. Scanning electron microscopy revealed that particles have a random and uniform distribution in the matrix especially in the less volume fraction of alumina particles, and strong mechanical bonding occurs at the interface of the particle matrix. According to the results of the tensile tests, it is observed that with less alumina content, the composite reinforced by nanosize particles has higher strength than that by submicrometre size particles. However, more reinforcement up to 3 vol.-% of submicrometre particles, as a result of including fewer microstructural defects, leads to better mechanical properties in comparison to the nanoparticle composite. 相似文献
10.
R. N. Singh 《Journal of Materials Science》1991,26(7):1839-1846
The influence of a silicon carbide whisker reinforcement on room temperature mechanical properties of a monolithic zircon ceramic and zircon composites uniaxially reinforced with silicon carbide monofilaments was studied in a flexure mode. The strength of a monolithic zircon was increased by the addition of whisker reinforcement, but the composite failure was still brittle in nature. In contrast, zircon composites reinforced with SiC whiskers and filaments showed toughened composite-like behaviour and produced higher first matrix cracking strength and toughness than the composites reinforced with only SiC filaments. In addition, the whisker reinforcement had insignificant influence on the ultimate strength of filament-reinforced composites. These results were related to changes in measured fibre-matrix interfacial properties, which indicated that composites with high first matrix cracking strength and toughness can be designed and fabricated via independently tailoring the matrix and the fibre-matrix interfacial properties. 相似文献
11.
《Materials Letters》2004,58(27-28):3509-3513
Magnesium metal matrix composites (MMCs) reinforced with 10, 20 and 30 vol.% TiB2 particulates, respectively, were fabricated by powder metallurgy. The microstructure, porosity, hardness and abrasive wear behavior of the composites were evaluated. Microstructural characterization of Mg MMCs showed generally uniform reinforcement distribution. As compared with pure Mg, the hardness (HB) values of Mg MMCs reinforced with 10, 20 and 30 vol.% TiB2 particulates were increased by 41%, 106% and 181%, respectively. The abrasive wear tests showed that the wear resistance of Mg MMCs is increased with the increasing of the reinforcement volume fraction. This was due to the strong particulate-matrix bonding and high hardness of the TiB2 particulate. 相似文献
12.
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
13.
This work focuses on the fabrication of aluminum (6061-T6) matrix composites (AMCs) reinforced with various weight percentage of B4C particulates by modified stir casting route. The wettability of B4C particles in the matrix has been improved by adding K2TiF6 flux into the melt. The microstructure and mechanical properties of the fabricated AMCs are analyzed. The optical microstructure and scanning electron microscope (SEM) images reveal the homogeneous dispersion of B4C particles in the matrix. The reinforcement dispersion has also been identified with X-ray diffraction (XRD). The mechanical properties like hardness and tensile strength have improved with the increase in weight percentage of B4C particulates in the aluminum matrix. 相似文献
14.
Explosive shock-compression processing is used to fabricate Ti3Al and TiAl composites reinforced with TiB2. The reinforcement ceramic phase is either added as TiB2 particulates or as an elemental mixture of Ti + B or both TiB2 + Ti + B. In the case of fine TiB2 particulates added to TiAl and Ti3Al powders, the shock energy is localized at the fine particles, which undergo extensive plastic deformation thereby assisting in bonding the coarse aluminide powders. With the addition of elemental titanium and boron powder mixtures, the passage of the shock wave triggers an exothermic combustion reaction between titanium and boron. The resulting ceramic-based reaction product provides a chemically compatible binder phase, and the heat generated assists in the consolidation process. In these composites the reinforcement phase has a microhardness value significantly greater than that of the intermetallic matrix. Furthermore, no obvious interface reaction is observed between the intermetallic matrix and the ceramic reinforcement. 相似文献
15.
《Materials Science & Technology》2013,29(1):93-101
AbstractThe tensile behaviour of Al–Cu–Mg alloy matrix composites produced by a powder metallurgy process was investigated as a function of particle size in the as extruded, homogenised, and peak aged conditions. The tensile behaviour of the corresponding matrix alloy which was produced in a similar manner, designated as Control, was also studied. There was a significant increase in the 0.2% yield strength of Control and all the metal matrix composites (MMCs) after homogenisation treatment (53–68%) and peak aging (93–109%), as compared to their values in the as extruded condition. The ultimate tensile strength (UTS) of Control as well as the MMCs also increases considerably after homogenisation treatment (39–70%), however, subsequent peak aging did not result in any further increase in UTS in case of any of the MMCs. It was found that the finer the reinforcement size, the higher the 0.2% yield strength and UTS in all the conditions. On the other hand, ductility decreased considerably after homogenisation treatment and subsequent peak aging. The results are discussed in the light of dislocation strengthening as well as reinforcement damage. 相似文献
16.
F. Tian 《Materials Research Bulletin》2011,46(7):1143-1147
Carbon nanotube-alumina hybrid reinforced high density polyethylene (HDPE) matrix composites were prepared by melt processing technique. Microstructure studies verified that the nanotubes consisting of well-crystallized graphite formed a network structure with Al2O3 in the hybrid, which was homogeneously dispersed in the HDPE matrix composites. Mechanical measurements revealed that 5% addition of nanotube-alumina hybrid results in 100.8% and 65.7% simultaneous increases in Young's modulus and tensile strength, respectively. Fracture surface showed homogenous dispersion of nanotubes and Al2O3 in the HDPE matrix and presence of interlocking like phenomena between hybrid and HDPE matrix, which might contribute to the effective reinforcement of the HDPE composites. 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.
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
19.
In the present study, hybrid magnesium based composites reinforced with an equivalent of 5 vol.% of micron and nano-sized Al2O3 particulates were synthesized using powder metallurgy technique incorporating an innovative microwave assisted rapid sintering technique. Microstructural characterization revealed near equiaxed grain morphology and the presence of minimal porosity in all the samples. Mechanical characterization studies revealed that the coupled addition of micron and nano-sized particulate reinforcements in magnesium matrix leads to a significant increase in hardness, elastic modulus, 0.2% yield strength, ultimate tensile strength and a decrease in ductility when compared to pure magnesium. Tensile testing results further revealed an increase in elastic modulus and ductility with no apparent change in the 0.2% yield strength and ultimate tensile strength of the hybrid composites upon the addition of nano-sized alumina particulates from 0.5 to 0.75 volume percent. With an increase in nano-sized alumina particulates from 0.75 to 1%, the overall mechanical properties of the hybrid composites were enhanced with an increase being observed in the elastic modulus, 0.2% yield strength and ductility of the composites. An attempt is made in this study to investigate the feasibility of the processing methodology and to study the effects of the addition of particulate reinforcements of different sizes on the microstructure, physical and mechanical properties of magnesium. 相似文献
20.
使用大尺寸球形Ti60钛合金粉与细小TiB2粉,通过低能球磨与反应热压烧结,成功制备了增强相呈网状分布的TiB晶须增强Ti60合金基(TiB_W/Ti60)复合材料。对TiB_W/Ti60复合材料进行热处理,以改善其组织结构与力学性能。结果表明:随着固溶温度的升高,TiB_W/Ti60复合材料基体中初生α相(密排六方相)含量减少,相应地转变β组织(α′(马氏体)+残留β相(体心立方相))含量增加,TiB_W/Ti60复合材料的抗拉强度升高,塑性降低;经过1 100℃/1h固溶处理之后,TiB_W/Ti60复合材料的室温抗拉强度为1 470 MPa,延伸率为1.9%。经过时效处理后,转变β组织中的α′相分解成细小α+β相。经过1 100℃/1h固溶+600℃/8h时效处理后TiB_W/Ti60复合材料的硬度达到HV538,抗拉强度达到1 552 MPa,延伸率为1.5%,经过1 000℃/1h固溶+600℃/8h时效处理,其抗拉强度达到1 460 MPa,延伸率为2.2%。 相似文献