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1.
In this present work nano coconut shell charcoal (ncsc) and silicon carbide (SiC) particulates were reinforced with AZ31B Mg alloy and suitable magnesium composite was developed by using the powder metallurgy technique followed by hot extrusion. Density measurement of the Mg composites revealed that the addition of ncsc significantly improved the density of the composites and porosity measurement showed minimal porosity. The microstructure of the composites showed even distribution of the ncsc in the AZ31B/3SiC Mg composite. The compressive and impact behaviour of the samples were characterized, the results showed that on increasing the weight percentage of ncsc in AZ31B/3SiC/0.5ncsc Mg composites the mechanical properties such as ultimate compressive strength, 0.2% yield strength, ductility and impact strength decreased. The scanning electron microscope (SEM) analysis of fractured surface of AZ31B Mg alloy and AZ31B/3SiC/0.5ncsc Mg composites showed quasi-cleavage fracture. The presence of ncsc above 0.5 wt% composites revealed mixture of quasi cleavage planes and some dimples. 相似文献
2.
《Materials Science & Technology》2013,29(7):823-832
AbstractIn the present study, elemental magnesium and magnesium–silicon carbide composites were synthesised using the methodology of fluxless casting followed by hot extrusion. Microstructural characterisation studies revealed low porosity and a completely recrystallised matrix in every material. The average size of the recrystallised grains was found to decrease with an increasing presence of SiC particulates. For the reinforced magnesium, fairly uniform distribution of SiC particulates and good SiC–Mg interfacial integrity was realised. The results of X-ray diffraction studies indicated the absence of oxide phases and no evidence of interfacial reaction products except in the case of Mg–26.0 wt-%SiC sample. Results of physical and mechanical properties characterisation revealed that an increase in the amount of SiC particulates incorporated leads to an increase in macrohardness and elastic modulus, which does not affect the 0.2% yield strength and reduces the ultimate tensile strength, ductility, and coefficient of thermal expansion. The weight percentage of SiC particulates when plotted against hardness and 0.2% yield strength revealed a linear correlationship. An attempt is made to investigate the effect of increasing amount of SiC particulates on the microstructural features, and physical and mechanical properties of the magnesium matrix. 相似文献
3.
《Composites》1993,24(3):276-281
The fracture behaviour and plane strain fracture toughness, KIC, of four 8090-based metal-matrix composites containing 20 weight % SiC particles, 3, 6 and 23 μm in diameter, has been evaluated as a function of matrix ageing condition. Toughness values are found to be almost independent of reinforcement size. Ageing at 170°C results in a monotonic decrease in toughness with increasing strength up to the peak condition, with no subsequent recovery in toughness on overageing. However, unlike reinforced 8090, the composites are not found to be susceptible to intergranular embrittlement on overageing. The observed trends are found to be independent of reinforcement size. These findings are explained in terms of the strength, work hardening behaviour and nature and distribution of void-nucleating particles in the matrix. 相似文献
4.
非连续增强铝合金复合材料的力学性能 总被引:2,自引:0,他引:2
用粉末冶金法制备了SiCp/铝合金复合材料,并对其进行了力学性能测试和断裂特性分析;综述了用不同工艺生产的非连续增强MMC的性能及影响因素;试图说明增强体/基体界面结合力是铝合金复合材料性能的控制因素;指出寻求适当的界面结合力是复合材料设计中的一个重要内容。 相似文献
5.
《Materials Science & Technology》2013,29(9-10):1065-1069
AbstractThe potential use of particle reinforced metal matrix composites (MMCs) for demanding structural applications highlights the need for an effective method to predict the fatigue performance of notched components. The present paper evaluates the ‘critical strain’ technique and its suitability with respect to particle reinforced MMC alloys. Strain controlled fatigue data generated on the aluminium alloy 2124 reinforced by two different fractions of 2–3 μm SiC particles are used to predict the lives of a ‘pseudocomponent’ representative of engineering situations. It is demonstrated that both alloys are essentially cyclically stable compared with monotonic work hardening curves and, where available, data from tension and torsion modes superimpose on a Von Mises effective stress-strain criterion. The implications of the fatigue life analysis are discussed. 相似文献
6.
《Materials Science and Engineering: A》2006,415(1-2):207-212
Characterizing residual stresses in the reinforcement of cast composites has been studied in the present work. Micro Raman Spectroscopy is a unique tool for determining the strain on the reinforced fibres in ceramic/polymer/metal matrix composites. Stress induced Raman shifts can be used to determine the stress/strain in films, fibres and particulates in composites. In this paper, the application of Micro Raman Spectroscopy as a non-destructive technique in providing information on the compressional/tensile strain in reinforcements in metal matrix composites is investigated. Examples are taken from hybrid Mg based composites reinforced with carbon fibres, Mg2Si in situ reinforcement, formed by the addition of Si in to the matrix and SiC particles. The studies on the strain measurements in as-cast condition and its comparison after thermal cycling of the composites using the bandwidth measured are discussed. Analysis of the bandwidth offers a tool to understand that the wavenumber shift is strain induced. With this, the compressional state of the fibres embedded in the matrix can be analysed. 相似文献
7.
This paper studied the combined effects of particle size and distribution on the mechanical properties of the SiC particle reinforced Al-Cu alloy composites. It has been shown that small ratio between matrix/reinforcement particle sizes resulted in more uniform distribution of the SiC particles in the matrix. The SiC particles distributed more uniformly in the matrix with increasing in mixing time. It has also been shown that homogenous distribution of the SiC particles resulted in higher yield strength, ultimate tensile strength and elongation. Yield strength and ultimate tensile strength of the composite reinforced by 4.7 μm sized SiC particles are higher than those of composite reinforced by 77 μm sized SiC particles, while the elongation shows opposite trend with yield strength and ultimate tensile strength. Fracture surface observations showed that the dominant fracture mechanism of the composites with small SiC particle size (4.7 μm) is ductile fracture of the matrix, accompanied by the “pull-out” of the particles from the matrix, while the dominant fracture mechanism of the composites with large SiC particle size (77 μm) is ductile fracture of the matrix, accompanied by the SiC particle fracture. 相似文献
8.
9.
《Materials Science & Technology》2013,29(7):590-595
AbstractThe tensile properties and microstructural evolution of hot extruded AZ91 magnesium alloy with and without reinforcement of SiC particles have been investigated in terms of extrusion parameters, such as extrusion ratio and extrusion temperature. Also, the effect of SiC particles on the grain size of the matrix in the composites was evaluated using the Hall-Petch equation. The AZ91 magnesium alloy powders prepared by wet attrition milling from magnesium machined chips were hot pressed with and without SiC particles, hot extruded, and then solution treated. Microstructural observation revealed that both the composites and the magnesium alloy have fine equiaxed grains due to the dynamic recrystallisation during hot extrusion. The tensile strength of both materials increased with increasing extrusion ratio, and the strengths of the composites were higher than that of the magnesium alloy without reinforcement. It was found that the tensile strength of both the materials decreased after solution treatment, and the decrease in tensile strength of the composites was considerably smaller than that of the magnesium alloy. From analyses of the microstructures and the mechanical properties, combined with examination of the H all–Petch relationship, the refinement of the matrix was primarily responsible for the improvement in the yield strength of the composites. The grain growth of the matrix was inhibited by the introduction of the SiC particles. 相似文献
10.
Yangyang Qiao Jinling Liu Yueqian Jia Chengying Xu Linan An Yuanli Bai 《International Journal of Fracture》2017,204(2):205-224
Experimental study on high volume fraction of metallic matrix nano composites (MMNCs) was conducted, including uniaxial tension, uniaxial compression, and three-point bending. The example materials were two magnesium matrix composites reinforced with 10 and 15% vol. SiC particles (50 nm size). Brittle fracture mode was exhibited under uniaxial tension and three-point bending, while shear dominated ductile fracture mode (up to 12% fracture strain) was observed under uniaxial compression. The original Modified Mohr–Coulomb (MMC) fracture model (Bai and Wierzbicki in Int J Fract 161:1–20, 2010; in a mixed space of stress invariants and equivalent strain) was transferred into a stress based MMC (sMMC) model. This model was demonstrated to be capable of predicting the coexistence of brittle and ductile fracture modes under different loading conditions for MMNCs. A material post-failure softening model was postulated along the damage accumulation to capture the above two different failure modes. This model was implemented to the Abaqus/Explicit as a material subroutine. Numerical simulations using finite element method well duplicated the material strength, fracture initiation sites and crack propagation modes of the Mg/SiC nano composites with a good accuracy. The proposed model has a good potential to predict fracture for a wide range of material with strength asymmetry and coexistence of brittle and ductile fractures modes. 相似文献
11.
This paper discusses the methodology of microstructure based elastic–plastic finite element analysis of particle reinforced metal matrix composites. This model is used to predict the failure of two dimensional microstructure models under tensile loading conditions. A literature survey indicates that the major failure mechanism of particle reinforced metal matrix composites such as particle fracture, interfaces decohesion and matrix yielding is mainly dominated by the distribution of particles in the matrix. Hence, analyses were carried out on the microstructure of random and clustered particles to determine its effect on strength and failure mechanisms. The finite element analysis models were generated in ANSYS, using scanning electron microscope images. The percentage of major failures and stress–strain responses were predicted numerically for each microstructure. It is evident from the analysis that the clustering nature of particles in the matrix dominates the failure modes of particle reinforced metal matrix composites. 相似文献
12.
《Composites Science and Technology》2007,67(3-4):737-745
The mechanical properties of high volume fraction SiC-particle reinforced Al-based metal matrix composites (MMCs) produced by means of pressurized liquid metal infiltration (squeeze casting) are shown to be triggered by matrix alloying and heat treatment procedures. It is distinguished between the effect of those alloying elements that only act on matrix strengthening, leaving the interface unaffected, and those alloying elements that interact with both (i.e. Mg). Among the first category a further sub-division is made between pure solid solution and precipitation hardening elements (i.e. Zn and Cu, ZnMg, respectively). In particular, this study addresses the effect of alloying and age hardening for AlCu3 and AlZn6Mg1 as well as the specific role of Mg additions to Al/SiC MMCs on interface microstructure formation, mechanical properties and fracture mode. For instance, it is shown that single additions of Mg catalyse the formation of Al4C3 whereas additions of Cu as well as (Zn + Mg) provide opportunities to enhance the composites’ strength. 相似文献
13.
The strain versus fatigue life and fracture behavior of spray-formed Al–Si composites reinforced with SiC particles of two
different sizes were studied under total strain amplitudes. Both composites exhibit short low-cycle fatigue (LCF) which follows
a Coffin-Manson relationship, and display cyclic hardening at all strain amplitudes. The LCF endurance of the composite with
large particles is higher than that of composite containing small particles in the high strain amplitudes, however, at low
strains the difference in fatigue endurance between the two composites decreased. Moreover, the decrease in particle size
results in a higher degree of hardening at low and middle strains, but reduces the magnitude of hardening at highest strain.
Fractographic analysis reveals that particle/matrix debonding is the main mechanism of failure in composite with small particles,
while fracture and debonding of SiC particle are predominant in the large particle reinforced composite. 相似文献
14.
采用微机控制电子万能实验机和分离式霍普金森压杆(SHPB)对石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料进行准静态压缩实验和动态冲击实验,研究石墨烯增强铝基复合材料在不同应变率下的冲击力学性能,采用SEM扫描电镜研究石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料的形貌特征。结果表明:在各个应变率载荷下,添加石墨烯和添加碳化硅都增强了铝合金的屈服强度,其中,添加石墨烯对铝合金的屈服强度提升更加明显,但不影响材料的应变硬化率;相较于在材料中添加碳化硅,添加石墨烯弱化了材料的应变率效应,在高应变率条件下,添加石墨烯降低了材料的强度极限;选取部分实验数据,拟合确定了添加石墨烯和添加碳化硅两种复合材料的J-C和Z-A本构方程的参数,并比较了两种本构模型的预测能力,对于本工作所研究的复合材料,J-C模型的预测能力更好。 相似文献
15.
《Materials Science & Technology》2013,29(7):955-958
AbstractMechanical spectroscopy has been used to study magnesium matrix composites reinforced either by long SiC fibres or randomly distributed Al2O3 (Saffil) short fibres. It is well known that, in metal matrix composites, thermal stresses can be built up at the interface due to the mismatch between the thermal expansion coefficients of matrix and reinforcements. In magnesium matrix composites, these thermal stresses are relaxed by dislocation motion in the matrix. This mechanism of thermal stress relaxation yields an extra transient component in the mechanical loss spectrum, which depends on the heating/cooling rate and disappears in isothermal condition in the behaviour of the shear modulus G with temperature has been observed during thermal cycling between 100 K and 500 K. The intensity of this phenomenondepends on the spatial distribution of the reinforcements in the matrix. In particular, composites reinforced with long fibres exhibit a more pronounced anomaly. This is interpreted by the modification of the interface strength when temperature is changed. 相似文献
16.
《Materials Science & Technology》2013,29(3):231-239
AbstractMetal matrix composites have been available in certain forms for at least two decades, e.g. boron fibre reinforced aluminium and various dispersed phase alloys and cermets. Recently, a range of alumina and silicon carbide fibres, whiskers, and particles with diameters <20 μm have become available. The possibilities of incorporating these materials into metals to improve stiffness, wear resistance, and elevated temperature strength without incurring weight penalties have attracted the attention of design engineers in the aerospace and automobile industries. The aim of the present paper is to outline the manufacturing processes for such composites, in particular those based upon liquid metal technology, e.g. squeeze casting and spray forming. Some of the mechanical and physical properties which have been determined for these materials are described. An analysis of how matrix alloy selection may influence tensile and fracture behaviour of short fibre and particle reinforced composites is attempted.MST/770 相似文献
17.
The axisymmetric cell model consisting of interface, matrix and reinforced particle is used to simulate the tensile test of particle reinforced metal matrix composite for predicting the micro stress/strain field and macro tensile stress/strain curve. In simulation of the tensile test, the cohesive element model is selected to model interfacial crack growth. It mainly analyzed the effects of interfacial properties, reinforcement volume fractions and aspect ratios on the stress–strain states of particle reinforced metal matrix composite. The results show that the peak micro stress and plastic strain occur at the interface in which it is a certain angle from the tensile stress direction; with the interfacial fracture toughness and reinforcement volume fraction increasing, the flow stress increases firstly and then decreases. The tensile stress–strain properties of SiC/6064Al are good when the interfacial fracture toughness is equal to 60 J/m and the reinforcement fraction volume is equal to 20%. Smaller reinforcement aspect ratio leads to smaller micro stress in composites. 相似文献
18.
Fabrication of SiC particles-reinforced magnesium matrix composite by ultrasonic vibration 总被引:1,自引:0,他引:1
K. B. Nie X. J. Wang K. Wu L. Xu M. Y. Zheng X. S. Hu 《Journal of Materials Science》2012,47(1):138-144
Magnesium matrix composites reinforced with two volume fractions (1 and 3%) of SiC particles (1 μm) were successfully fabricated
by ultrasonic vibration. Compared with as-cast AZ91 alloy, with the addition of the SiC particles grain size of matrix decreased,
while most of the phase Mg17Al12 varied from coarse plates to lamellar precipitates in the SiCp/AZ91 composites. With increasing volume fraction of the SiC
particles, grains of matrix in the SiCp/AZ91 composites were gradually refined. The SiC particles were located mainly at grain
boundaries in both 1 vol% SiCp/AZ91 composite and 3 vol% SiCp/AZ91 composite. SiC particles inside the particle clusters may
be still separated by magnesium. The study of the interface between the SiC particle and the alloy matrix suggested that SiC
particles bonded well with the alloy matrix without interfacial reaction. The ultimate tensile strength, yield strength, and
elongation to fracture of the SiCp/AZ91 composites were simultaneously improved compared with that of the as-cast AZ91 alloy. 相似文献
19.
The tensile deformation and fracture behaviour of aluminium alloy 2124 reinforced with different amounts of silicon carbide particulates was studied, in the as-extruded and heat-treated conditions, with the objective of investigating the influence of heat treatment and composite microstructural effects on tensile properties and quasi-static fracture behaviour. Results indicate that for a given microstructural condition, the elastic modulus and strength of the metal-matrix composite increased with reinforcement content in the metal matrix. For a given volume fraction of reinforcement, the heat-treated composite exhibited significantly improved modulus and strength-ductility relationships over the as-extruded counterpart. The increased strength of the Al-SiC composite is attributed to the competing and synergistic influence of strengthening precipitates in the matrix metal, residual stresses generated due to intrinsic differences in thermal expansion coefficients between components of the composite and strengthening from constrained plastic flow and triaxiality in the ductile matrix due to the presence of brittle reinforcement. Fracture on a microscopic scale is initiated by cracking of the individual or clusters of SiC particles present in the microstructure. Particle cracking was dominant for the as-extruded composite microstructure. For both the as-extruded and heat-treated conditions, particle cracking increased with reinforcement content in the matrix. Final fracture of the composite resulted from crack propagation through the matrix between clusters. Although these composites exhibited limited ductility on a macroscopic scale, on a microscopic scale the fracture mechanism revealed features reminiscent of ductile failure. 相似文献
20.
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