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1.
The tensile properties of aluminum matrix composites containing SiC whiskers or particulate were investigated analytically
and compared to experimental results. Two finite-element models were constructed and used for elastoplastic analysis. In both
models, the SiC fibers are represented as longitudinally aligned cylinders in a three-dimensional array. The cylinder ends
are transversely aligned in one model and staggered in the other. Using the models, the sensitivity of the predicted composite
properties to the deformation characteristics of the matrix alloy was examined, and the general behavior of the models was
validated. It was determined that both models are necessary to predict the overall composite stress-strain response accurately.
The analytic results accurately predict: the observed composite stress-strain behavior; the experimentally observed increase
in Young’s modulus and the work-hardening rate with increasing fiber volume content and aspect ratio; and the decrease and
subsequent increase in proportional limit as the SiC volume fraction is increased. The models also predict that the transverse
material properties should be insensitive to fiber aspect ratio. In addition, the model predicts the location of initial yielding
and the propagation of the plastic region. These results offer insights into the deformation mechanisms of short fiber-reinforced
composites. 相似文献
2.
3.
《Scripta Metallurgica et Materialia》1995,32(3):325-330
The interfacial shear strength of Nicalon SiC fiber-reinforced glass-ceramic matrix composites was aimed to be tailored via two methods: (1) varying of the thickness of the carbon-rich interfacial layer between the fiber and the matrix by controlling hot pressing period and (2) formation of the secondary interfacial layer, TaC, at the carbon/matrix boundary by doping the Ta2O5 matrix addition. In the series of composites with varying carbon-rich layer thickness, fiber/matrix debonding mostly occurred at the carbon/matrix boundary and hence the increase in the carbon-rich layer thickness did not cause any apparent changes in the interfacial shear strength. In the TaC formed series of composites, the interfacial shear strength was affected considerably by the presence of the TaC phase at carbon/matrix boundary. The Ta2O5 addition to control the quantity of the TaC phase has shown to be a useful method to tailor the interfacial shear strength of SiC fiber/glass-ceramic composites. 相似文献
4.
T. P. D. Rajan R. M. Pillai B. C. Pai 《Metallurgical and Materials Transactions A》2002,33(8):2755-2761
Aluminosilicate short fibers are one of the less expensive reinforcements used for the fabrication of metal matrix composites
(MMCs). The present investigation evaluates the interfacial characteristics of Al-7Si-0.4Mg (356) alloy reinforced with 10
wt pct aluminosilicate short fibers using optical microscopy, electron microscopy, and X-ray analysis. The fibers used are
standard- and zirconiagrade aluminosilicate short fibers. The interfacial analysis has shown the formation of MgAl2O4 and Si in both grades of fibers. In addition, ZrAl3 formation is observed in the zirconia-grade fiber because of the interaction between the matrix and the dispersoid. The zirconia-grade
fiber is more susceptible to interfacial reaction than the standard-grade fiber because of the presence of the highly reactive
ZrO2 phase and a lower amount of the Al2O3 phase, which provides resistance to the reaction. 相似文献
5.
采用粉末冶金法制备SiC/C-Cu复合材料,研究SiC颗粒含量对该材料组织结构与物理性能的影响,并在HST-100载流摩擦磨损试验机上进行载流磨损试验,研究摩擦速度、电流密度与SiC颗粒含量对SiC/C-Cu复合材料磨损率的影响以及磨损机理的变化。结果表明:SiC颗粒均匀分布于铜基体中。随SiC含量增加,复合材料的硬度和孔隙率都逐渐增大,密度和导电率降低。添加SiC颗粒可增强C-Cu复合材料的抗磨损性能,材料的磨损率随摩擦速度和电流密度增加而增加,随SiC含量增加呈先降低后上升的趋势,含2%SiC(质量分数)的SiC/C-Cu复合材料具有优异的抗载流磨损性能。添加SiC颗粒可减少摩擦磨损过程中铜基体的粘着磨损,磨损机理主要为磨粒磨损和电弧侵蚀磨损。 相似文献
6.
The creep rupture life of an Al/Al2O3 composite and its creep behavior were studied. The metal matrix composite was produced by using a squeeze casting technique.
High-temperature tensile tests and creep experiments were conducted on a 15 vol pct alumina fiber-reinforced AC2B Al alloy
metal matrix composite (MMC). The high-temperature tensile strength of Al/Al2O3 composite is 14 pct higher than that of an AC2B Al alloy. The steady-state creep rate and the creep life were measured. The
stress exponent in Norton’s equation and the activation energy were computed. The stress exponents of the AC2B and Al/Al2O3 composites were found to be 4 and 12.3, respectively. The activation energy of the AC2B and Al/Al2O3 composites was found to be 242.74 and 465.35 kJ/mol, respectively. A new equation for predicting creep life was established,
which was based on the conservation of the creep strain energy. The theoretical predictions were compared with those of the
experiment results, and a good agreement was obtained. It was found that the creep life is inversely proportional to the (n + 1)th power of the applied stress and strain failure energy of creep is conserved. The creep fracture surface, examined
by scanning electron microscopy (SEM), showed that the MMC specimen failed in a brittle manner. 相似文献
7.
The transverse creep response of an 8-ply SiC (SCS-6)/Ti-6Al-4V composite was measured at 482 °C from 69 to 276 MPa. Creep
samples with fibers exposed at the edges as well as specimens with fully embedded fibers were tested under stepped loading
conditions with increasing load. The response of each sample geometry was compared with creep data from the unreinforced matrix
(‘neat’ material). The samples with exposed fiber ends exhibited minimum creep rates that were higher than those of the neat
material at all stresses, and the stress exponent was slightly large than the neat material. The embedded fiber samples possessed
minimum creep rates that were smaller than the neat material at low stresses (<115 MPa), but became equivalent to the exposed
fiber data at the highest stress (276 MPa). The apparent stress exponent for the embedded fiber composite was significantly
larger than the neat material. The exposed fiber test data were well represented by a standard Crossman analysis, where the
fibers were considered to have completely debonded. A stress singularity in the interfacial region at the sample edge is responsible
for this behavior. The Crossman model was modified to incorporate the effect of a finite interface strength (120 MPa), and
this was used to describe the response of the samples with embedded fibers. A reasonable fit to this representation was obtained.
However, the measured minimum creep rate at the lowest stress was significantly lower than that predicted by the Crossman
analysis for fully bonded fibers.
This article is based on a presentation made in the symposium “Fatigue and Creep of Composite Materials” presented at the
TMS Fall Meeting in Indianapolis, Indiana, September 14–18, 1997, under the auspices of the TMS/ASM Composite Materials Committee. 相似文献
8.
9.
M. Jacquesson A. Girard M.-H. Vidal-Sétif R. Valle 《Metallurgical and Materials Transactions A》2004,35(10):3289-3305
The thermomechanical (dilatometric, tensile, and fatigue) behavior of Al-based metal matrix composites (MMCs) is investigated.
These composites are reinforced by quasi-unidirectional (quasi-UD) woven fabric preforms with 90 pct of continuous fibers
in the longitudinal direction and 10 pct in the transverse direction. The two composite systems investigated feature a highly
ductile matrix (AU2: Al-2Cu wt pct) with a strongly bonded fiber-matrix interface (N610 alumina fibers) and an alloyed, high-strength
matrix (A357: Al-7Si-0.6Mg wt pct) with a weak fiber-matrix interface (K139 carbon fibers). Microstructural investigation
of the tested specimens has permitted identification of the specific characteristics of these composites: undulation of the
longitudinal bundles, presence of the straight transverse bundles, interply shearing, and role of brittle phases. Moreover,
simple semiquantitative models (e.g., interply shearing) have enabled explanation of the specific mechanical behavior of these quasi-UD composites, which exhibit
high tensile and fatigue strengths, as compared with the corresponding pure UD composites. Knowledge of the specific characteristics
and mechanical behavior of these quasi-UD composites will facilitate the further investigation of the (0, ±45, 90 deg) quasi-UD
laminates (Part II). At a more theoretical viewpoint, the specific geometry and behavior of these quasi-UD composites allows
exacerbation of fatigue mechanisms, even more intense than in “model” composites. 相似文献
10.
Interface characterization of duplex metal-coated SiC fiber-reinforced Ti-15-3 matrix composites 总被引:2,自引:0,他引:2
S. Q. Guo Y. Kagawa A. Fukushima C. Fujiwara 《Metallurgical and Materials Transactions A》1999,30(3):653-666
The interfacial reaction behavior of duplex metal (Cu/Mo and Cu/W)-coated SiC (SCS-6) fiber-reinforced Ti-15-3 composites,
before and after thermal exposure, has been studied. The effect of thermal exposure on the shear sliding resistance of these
composites was also obtained using a thin-specimen push-out test. The results are compared to those of an original SiC (SCS-6)
fiber-reinforced Ti-15-3 composite. The interfacial reaction behavior is strongly affected by the existence of a coating layer.
Both the Cu/Mo and Cu/W coating layers prevent the growth of a reaction layer. However, the coatings could not effectively
prevent diffusion of alloying elements; only the W layer exists after the thermal exposure. On the other hand, the interface
shear sliding stress minimally depends on the duplex metal coating layers prior to the thermal exposure, and this sliding
stress in both the SiC/Cu/Mo/Ti-15-3 and SiC/Cu/W/Ti-15-3 composites decreases slightly relative to that in the SiC/Ti-15-3
composite. After thermal exposure, the interface shear sliding stress increases for the SiC/Ti-15-3 composite. In distinction,
the interface shear sliding stress significantly decreases after thermal exposure in both the SiC/Cu/Mo/Ti-15-3 and SiC/Cu/W/Ti-15-3
composites. Theses behaviors are attributed to the decrease of radial clamping stress, which originates from a volume expansion
associated with the β → α phase transformation. 相似文献
11.
《Acta Metallurgica Materialia》1992,40(9):2307-2313
The mode I fracture resistance has been measured for Al and Al/4 Mg matrix composites, unidirectionally reinforced with ceramic fibers, prepared using a squeeze casting technique. Effects of SiC particle additions have also been investigated. The Al/4 Mg system had a high toughness, whereas the Al matrix system had a relatively low fracture resistance. In all cases, the addition of particulates slightly decreased the resistance to crack growth. The fracture resistance was simulated by a ductile bridging model with plastic dissipation occurring within a zone governed by the fiber spacing. The tensile strength of these composites has been estimated, based on the resistance behavior and microstructure. 相似文献
12.
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
13.
14.
以短炭纤维为增强纤维,以炭粉、Si粉和树脂为基体来源,采用温压—原位反应法制备C/C-SiC材料,研究该材料的力学性能及破坏机理。结果表明:C/C-SiC制动材料的纵向和横向抗弯强度分别为76 MPa和62 MPa,以韧性断裂为主,弯曲破坏表现为裂纹偏转、纤维桥接、纤维拔出和界面脱粘。纵向抗压强度达112 MPa,纵向压缩破坏表现为韧性断裂,以对角剪切破坏方式为主;横向抗压强度达84 MPa,横向压缩破坏主要表现为脆性断裂,以多层复合剪切破坏方式为主。材料的冲击韧性为3.1 kJ/m2。 相似文献
15.
Tadahiko Miyoshi Hironori Kodama Hiroshi Sakamoto Akihiro Goto Shiroo Iijima 《Metallurgical and Materials Transactions A》1989,20(11):2419-2423
Silicon carbide ceramics’ matrix composites with SiC or C filaments were fabricated through hot pressing, and the effects
of the filament pullout on their fracture toughness were experimentally investigated. The C-rich coating layers on the SiC
filaments were found to have a significant effect on the frictional stress at the filament/matrix interfaces, through assising
the filamet pullout from the matrix. Although the coating layers were apt to burn out in the sintering process of SiC matrix
compposites, a small addition of carbon to the raw materials was found to be effective for the retention of the layers on
the fibers, thus increasing the fracture toughness of the composites. The fracture toughness of the C filament/SiC matrix
composite increased with temperature due to the larger interfacial frictional stress at higher temperatures, because of the
higher thermal expansion of the filament in the radial direction than that of the matrix. 相似文献
16.
The deformation and failure mechanisms under cyclic deformation in an 8090 Al-Li alloy reinforced with 15 vol pct SiC particles
were studied and compared to those of the unreinforced alloy. The materials were tested under fully reversed cyclic deformation
in the peak-aged and naturally aged conditions to obtain the cyclic response and the cyclic stress-strain curve. The peak-aged
materials remained stable or showed slight cyclic softening, and the deformation mechanisms were not modified by the presence
of the ceramic reinforcements: dislocations were trapped by the S′ precipitates and the stable response was produced by the mobile dislocations shuttling between the precipitates to accommodate
the plastic strain without further hardening. The naturally aged materials exhibited cyclic hardening until failure, which
was attributed to the interactions among dislocations. Strain localization and slip-band formation were observed in the naturally
aged alloy at high cyclic strain amplitudes, whereas the corresponding composite presented homogeneous deformation. Fracture
was initiated by grain-boundary delamination in the unreinforced materials, while progressive reinforcement fracture under
cyclic deformation was the main damage mechanism in the composites. The influence of these deformation and damage processes
in low-cycle fatigue life is discussed. 相似文献
17.
A micromechanical model is developed to compute the stress-strain curve of particle-reinforced metal-matrix composites under
monotonic and cyclic deformation. The composite was modeled as a three-dimensional array of hexagonal prisms, each containing
an intact or fractured reinforcement. The average stresses acting on the intact and damaged cells — as well as on the ceramic
particles — were computed from the finite-element analysis of axisymmetric cylindrical cells, and the overall composite response
was then calculated through an isostrain approach. The model was validated against the experimental results, reported in Parts
I and II of this article, for an 8090 Al alloy reinforced with 15 vol pct SiC particles,[1,2] where the matrix and reinforcement properties were obtained from mechanical tests on the unreinforced alloy and from quantitative
microscopy analyses of the fraction of broken reinforcements in the composite. The critical mechanisms which controlled the
deformation and damage processes in the composite during monotonic and cyclic deformation are discussed in light of the model
results. 相似文献
18.
《Acta Metallurgica Materialia》1990,38(12):2485-2492
The influence of the properties of the fibers, the matrix and the interface on the mechanical properties of fiber reinforced ceramics is analyzed by a simplified method previously developed by the authors for cohesive materials. The method parts from the assumption that crack displacements are known a priori and furnishes, in a simple and easy way, the fracture resistance curves versus crack length. The numerical results from the model are compared with experimental data from the literature. Finally, the model is used to assess the influence of fiber strength, interface slipping shear stress, fiber radius and fiber defect distribution on the fracture resistance and ductility of fiber-reinforced ceramic composites. 相似文献
19.
A micromechanical model is developed to compute the stress-strain curve of particle-reinforced metal-matrix composites under
monotonic and cyclic deformation. The composite was modeled as a three-dimensional array of hexagonal prisms, each containing
an intact or fractured reinforcement. The average stresses acting on the intact and damaged cells—as well as on the ceramic
particles —were computed from the finite-element analysis of axisymmetric cylindrical cells, and the overall composite response
was then calculated through an isostrain approach. The model was validated against the experimental results, reported in Parts
I and II of this article, for an 8090 Al alloy reinforced with 15 vol pct SiC particles,[1,2] where the matrix and reinforcement properties were obtained from mechanical tests on the unreinforced alloy and from quantitative
microscopy analyses of the fraction of broken reinforcements in the composite. The critical mechanisms which controlled the
deformation and damage processes in the composite during monotonic and cyclic deformation are discussed in light of the model
results. 相似文献
20.
The interfacial reaction characteristics of SCS-6, Sigma, and B4C/B fibers with nickel aluminide (Ni3Al) matrix have been investigated between 780°C to 980°C for times ranging from 1 to 100 hours. The microstructure and elemental
compositions across the reaction zone have been analyzed quantitatively using microscopy and electron probe microanalyses,
respectively. The results show that Ni3Al reacts extensively with SCS-6, Sigma, and B4C/B fibers to form complex reaction products, and Ni is the dominant diffusing species controlling the extent of reaction.
In the SiC/Ni3Al composite, the C-rich layer on the SiC surface can slow down but cannot stop the inward diffusion of Ni into SiC fiber.
When the C-rich layer is depleted, a rapid increase in reaction zone thickness occurs. Diffusion barrier coating on the fibers
is required to minimize the interfacial reactions. 相似文献