Effect Of Reinforcement Volume Fraction Research Articles

Fabrication and interface optimization of continuous CF/Al composites with different reinforcement volume fraction

Interface is the key factor to determine the properties of composites. In this work, the Ni coated continuous CF/Al composites were fabricated via twin-roll casting method. After interface optimization, the interfacial bonding strength was enhanced and the dispersion of carbon fibers was improved. The effect of reinforcement volume fraction on microstructure, mechanical properties and strengthening mechanism of CF/Al composites was studied. The microstructural showed that the increase of reinforcement volume fraction was easy to cause more defects in composites. Transmission electron microscopy (TEM) and thermodynamic calculation were used to characterize the interfacial phase composition of composites after interface optimization. The results revealed that the exterior of carbon fibers bundle was mainly composed of Al3Ni intermetallic phase, and there was no obvious Al4C3 phases were found interior of the CFs bundle. In addition, the composites with 13.6 vol% CFs had the best UTS of 218.7 MPa and well dispersion. Furthermore, Vickers hardness test and Nano-indentation results showed that Al-Ni intermetallic compound can enhance the whole hardness of CF/Al composites. Dislocation strengthening in the Al-Ni intermetallic compound region was observed by TEM. The interface evolution mechanism of CF/Al composites were revealed for the first time.

Effects of Reinforcement Volume Fraction on Mechanical Properties and Microstructures of 7075Al Matrix Composites Reinforced by FeCoCrNiAl High-Entropy Alloy Particles

High-entropy alloy particles reinforcements improve the mechanical properties of aluminum matrix composites while increasing its density. Investigating the effects of the reinforcement content is conducive to the fabrication of lightweight and high strength composites. FeCoCrNiAl high-entropy alloy particles (HEAp) reinforced 7075Al matrix composites (HEAp/Al) with different HEAp volume fractions of 5, 10, 15, and 20 vol% were fabricated via a vacuum ball milling and vacuum hot pressing sintering, and then the microstructures, interface, density, and mechanical properties of the HEAp/Al composites were characterized. The results indicated that composites with high relative density can be obtained with a holding time of 10 min at 580 °C, 30 MPa; the HEAp distribution was homogeneous as the increase of reinforcement volume fraction decreases and forms agglomeration, especially when the volume fraction is up to 15 vol% and 20 vol%; the density and hardness of HEAp/Al composites improved with the increase of reinforcements’ volume fraction, whereas the flexural strength and fracture toughness of HEAp/Al composites increased at first and then decreased; the HEAp/Al composites reinforced by 10 vol% HEAp showed the maximum flexural strength and fracture toughness, which were increased by 124.6% and 107% compared with 7075Al, respectively; the improvement of mechanical properties was attributed to the dislocation strengthening behavior and load transfer effect of the HEAp reinforcement.

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

Effect of reinforcement volume fraction and T6 heat treatment on microstructure, thermal and mechanical properties of mesophase pitch-based carbon fiber reinforced aluminum matrix composites

To meet the requirements of structural and functional integration, machinability and workability of engineering materials, continuous mesophase pitch-based carbon fiber (MPCF) reinforced 2024 aluminum (Al) matrix composites with 20–50 vol % MPCF were fabricated by vacuum hot pressing method. The effects of MPCF volume fraction and T6 heat treatment on microstructure, thermal and mechanical properties of MPCF/2024Al composites were investigated. The results show that the interface of the as-sintered composite was well bonded. After T6 heat treatment, the amorphous layer at the interface changed from continuous to discontinuous and the interfacial bonding was further improved, but there was no interfacial reaction. The increase of MPCF volume fraction was beneficial to improve the thermal conductivity (TC) and elastic modulus (E) of the as-sintered composites, up to 258.3 W/(m⋅K) and 343.5 GPa respectively, while the composites with 30 vol % and 40 vol % MPCF respectively had the highest ultimate tensile strength (UTS) and a coefficient of thermal expansion (CTE) close to zero. After heat treatment, the TC and E were slightly changed, while the CTE was further reduced and UTS was significantly improved. In this work, the heat-treated composite with 30 vol % MPCF had the highest UTS of 499.3 MPa and good thermal properties, and the TC of this composite may be further improved by using MPCFs with higher TC. Therefore, this composite is expected to become a promising engineering material integrating structure and function.

Effect of Material and Process Variables on Characteristics of Nitridation-Induced Self-Formed Aluminum Matrix Composites-Part 1: Effect of Reinforcement Volume Fraction, Size, and Processing Temperatures.

This paper investigates the effect of the size and volume fraction of SiC, along with that of the processing temperature, upon the nitridation behavior of aluminum powder during the nitridation-induced self-formed aluminum composite (NISFAC) process. In this new composite manufacturing process, aluminum powder and ceramic reinforcement mixtures are heated in nitrogen gas, thus allowing the exothermic nitridation reaction to partially melt the aluminum powder in order to assist the composite densification and improve the wetting between the aluminum and the ceramic. The formation of a sufficient amount of molten aluminum is key to producing sound, pore-free aluminum matrix composites (AMCs); hence, the degree of nitridation is a key factor. It was demonstrated that the degree of nitridation increases with decreasing SiC particle size and increasing SiC volume fraction, thus suggesting that the SiC surface may act as an effective pathway for nitrogen gas diffusion. Furthermore, it was found that effective nitridation occurs only at an optimal processing temperature. When the degree of nitridation is insufficient, molten Al is unable to fill the voids in the powder bed, leading to the formation of low-quality composites with high porosities. However, excessive nitridation is found to rapidly consume the nitrogen gas, leading to a rapid drop in the pressure in the crucible and exposing the remaining aluminum powder in the upper part of the powder bed. The nitridation behavior is not affected by these variables acting independently; therefore, a systematic study is needed in order to examine the concerted effect of these variables so as to determine the optimal conditions to produce AMCs with desirable properties for target applications.

Competing failure mechanisms in metal matrix composites and their effects on fracture toughness

Development of high performance Metal Matrix Composites (MMCs) requires careful microstructure design which can improve material's fracture toughness while maintaining high strength. Microstructure and constituent properties combine to determine the overall fracture toughness of MMCs through the activation of different deformation and failure mechanisms. Although the effects of key microstructural attributes on the fracture toughness of MMCs have been discussed in previous studies, their effects on the interplay between plastic deformation and crack formation, as well as their effects on the competing failure mechanisms have not been systematically studied. In this paper, an integrated experimental and analytical framework is presented to evaluate the fracture toughness of MMCs through an assessment of energy contributions in terms of plastic deformation and crack surface formation in the matrix, reinforcement particles and interface. J-integral is calculated through displacement field measurement using Digital Image Correlation method. The competition of different failure mechanisms and their relations with material deformation are quantified through an analytical model by considering the effects of reinforcement volume fraction, interfacial property and yield stress of the matrix. Calculations carried out concern 6092Al/SiCp, but the overall approach applies to other MMCs as well. Results from this work indicate that interface debonding is a beneficial failure mechanism for fracture toughness enhancement of MMCs. It not only increases the surface energy dissipation by creating tortuous crack paths, but also promotes plastic deformation in the ductile matrix which largely contributes to the toughening of MMCs. The activation of interface debonding primarily depends on the volume fraction of SiCp, the yield stress of Al and the interface bonding energy.

Effect of Reinforcement Volume Fraction on the Wear Behavior of Al-SiCp Composites Prepared by Spark Plasma Sintering

Most investigations on MMCs were carried out using conventional methods. Employing a different approach, this study concentrated on compaction, hardness and wear behavior of Al-SiC composites with different reinforcement volume fractions (5–15%) by spark plasma sintering method. Hardness and density test results of the composite samples used in this study were significantly higher than conventionally produced composites. Such increase in density and hardness resulted in lower wear rate. To study the effect of applied load on samples wear behavior, wear tests were carried out under 1, 3 and 10 N loads with 0.07 m/s sliding rate. Results revealed that in all the applied loads, composite samples had lower wear rates and lower friction coefficients than those of unreinforced aluminum. Conversely, increase in volume fraction of reinforcement particles led to decrease in wear rates and friction coefficients of the composite specimens which were more tangible in Al-15%SiC sample. Obtained data showed that by increasing the applied load, friction coefficient and wear rate increased in all the samples. Also dominant wear mechanism was determined using SEM micrographs of sample surfaces after wear tests.

Effect of reinforcement volume fraction on the mechanical properties of the Al-SiC nanocomposite materials

Particle reinforced metal matrix composites (MMCs) has emerged as one of the potential materials for structural application due to their superior mechanical properties. However, these MMCs have poor damage tolerance due to their low fracture toughness. The volume fraction of reinforcement plays a significant role to improve the overall strength of the MMCs. In this research, Al matrix composites reinforced with three different volume fraction of the SiC nanoparticles were fabricated by a powder metallurgy process and the effects of volume fraction on the mechanical properties of the Al-SiC nanocomposite was investigated. The samples were prepared with 200 kN compaction load and 600°C sintering temperature. Subsequently, their mechanical testing was carried out. The density and hardness of the samples were investigated. Moreover, the microstructure of the nanocomposites was examined by optical microscope. The results showed that the high volume fraction reinforced nanocomposite exhibited better microstructural feature and high hardness as compared to the low volume fraction reinforced nanocomposite. Therefore, the high volume fraction reinforced nanocomposite can be a potential material to use in the brake disc of the automobile.

Fabrication and characterization of squeeze cast A413-CSF composites

Abstract A413 aluminum matrix composites reinforced with short carbon fibers (CSFs) were produced using a combination of vortex and squeeze casting processes and the effects of reinforcement volume fraction and reinforcement coating on density, porosity, reinforcement distribution and mechanical properties of the produced composites were studied. The results showed that increasing the volume fraction of CSFs led to decreased density and increased porosity of the cast composites. Distribution of uncoated CSFs in the matrix of the reinforced samples was poor and most of the fibers were in agglomerated bundle form. Utilization of coated CSFs resulted in a rather uniform distribution of the reinforcement in the matrix. Mechanical properties of squeeze cast composites fabricated using uncoated CSFs improved by increasing the reinforcement volume fraction up to 2% and decreased beyond it. Mechanical properties of the squeeze cast composites fabricated using coated CSFs improved steadily by increasing the reinforcement volume fraction up to 3%. Ultimate tensile strength and hardness values of the composites reinforced with 3 vol% coated CSFs increased by more than 100% and 60%, respectively, in comparison with those of the monolithic cast sample.

Effect of reinforcement volume fraction and orientation on a hybrid tissue engineered aortic heart valve with a tubular leaflet design

Transcatheter aortic valve implantation of fibrin-based tissue engineered heart valves with a tubular leaflet construct have been developed as an alternative to invasive traditional surgical heart valve implantation. In general, they are well suited for the pulmonary position, but display insufficient mechanical properties for the aortic position. To enable the application of tissue-engineered valves in the systemic circulation, the tissue is reinforced with a textile scaffold. The current study seeks to compare the effect of varying the fiber volume fraction and orientation of bidirectional textile reinforcement on the closed-valve configuration. An anisotropic large deformation material model based on structural tensors was chosen and the materials were characterized. A finite element model was constructed of the heart valve, and the pinching and suturing of the corners along with application of pressure was simulated. Virtual experiments were conducted with fiber volume fractions of 0.1, 0.01, 0.001, and 0.0001 for ±45° fiber orientations. Furthermore, volume fraction was held at 0.01 and fiber orientations of 0°, ±15°, ±30°, ±45°, ±60°, ±75° and 90° from the tube’s axial direction were simulated and compared. It was shown that increasing the fiber volume fraction decreased the maximum principle strain in the valve, but lead to less closure. Additionally, the effect of fiber orientation affected the strains differently at different locations, depending on the local deformed geometry. This indicates that a non-uniform fiber distribution using tailored fiber placement could be used to optimize reinforcement design.

Microstructures and Mechanical Properties of In Situ Al2O3/Al-Si Composites Fabricated by Reaction Hot Pressing

Three in situ formed Al2O3/Al-Si composites with a different volume fraction of 10, 20, and 30 vol pct were fabricated using low energy ball milling and reaction hot pressing. The effect of reinforcement volume fraction on the microstructure and mechanical properties were studied. When the volume fraction was 30 vol pct, a massive primary Si (~130 µm) along with an increase of Al2O3 (~2 µm) was observed. The YS, UTS, and Brinell hardness of the composites were significantly higher than the aluminum matrix. Mechanisms governing the tensile fracture process are discussed.

Effects of reinforcement volume fraction on tensile behaviors of laminated Ti–TiBw/Ti composites

A range of laminated Ti–TiBw/Ti composites composed of Ti layer and TiBw/Ti composite layer with different volume fractions of TiB whisker (TiBw) were successfully fabricated by diffusion welding. TiBw reinforcement exhibits different morphologies, such as needle-like, self-joining, claw-like and cluster structures due to the increasing volume fractions of TiB. The elastic modulus and yield strength of the laminated composites with different volume fractions of TiB are consistent with the HT equation and shear lag model, respectively. The ultimate tensile strength of the laminated composites with 5vol%, 8vol%, 10vol% and 12vol% TiBw/Ti composite layer is 604MPa, 689MPa, 744MPa and 789MPa, along with tensile elongation of 19.7%, 14.1%, 10.4% and 5.5%, respectively. The fracture characteristics of the laminated composites reveal a ductile to brittle transition (DBT) behavior with the increase of TiB volume fraction: fractograph in TiBw/Ti composite layer changes from tortuous into flatter, and Ti layer changes from ductile fracture accompanying with many dimples into brittle fracture with many lath-like fracture morphologies, which are attributed to the decreasing size of plastic zone at the tunnel crack tip.

An experimental and statistical study of interaction effects of matrix particle size, reinforcement particle size and volume fraction on the flexural strength of Al–SiCp composites by P/M using central composite design

Abstract In this study, the effects of reinforcement volume fraction, matrix and reinforcement particle sizes and their interactions on the flexural strength of Al–SiCp metal matrix composites manufactured by powder metallurgy method were investigated by using central composite design (CCD). An experimental plan for CCD with three factors and five levels was used to optimize the required number of experiments. The fabricated composites were reinforced with SiC particles of 2.39, 7.5, 15, 22.5 and 27.61 volume fractions. The particle sizes of 45, 62, 87, 112, and 129 μm were determined for both matrix and reinforcement particles. Experimental and numerical results show that the main effects of factors and their interactions are significant on the flexural strength. Among all factors, the main effect of volume fraction dominates the main effect of other two factors. Interaction between matrix particle size and reinforcement particle size is much more important at low volume fraction compared to that at high volume fraction. The high flexural strength values at low volume fractions are obtained when matrix particle size is equal to or smaller than reinforcement particle size while those at high volume fraction can be only reached when matrix particle size is much smaller than that of reinforcement particle.

Effects of Reinforcement Volume Fraction on the Abrasive Wear Behaviour of Al—MgO Composites Produced by the Vacuum Infiltration Method

In this study, the effects of the reinforcement volume fraction on the abrasive wear behaviour of reinforced MgO composites produced by the vacuum infiltration method with 5, 10, and 15 vol% of the volume fraction of Al matrix were investigated. The abrasive wear tests were carried out by 80, 100, and 180 mesh Al2O3 abrasive paper and the pin-on-disc wear device under 10, 20, and 30 N loads at 0.2 m/s sliding speed for 3 s. At the end of the wear tests, scanning electron microscope photographs of worn surfaces were taken and the microstructures were analysed by energy dispersive spectrometer (EDS). By checking the images of the worn surfaces, it was observed that the abrasive wear effect increased by increasing the reinforcement ratio. The maximum wear loss was reported under 30 N loads and by 80 mesh abrasive paper. It was found that according to the increment of reinforced MgO in the composite, the amount of wear also increased. On the other hand, the amount of porosity and the reinforcement volume fraction are crucial parameters in the abrasive wear effect.

Effect of Reinforcement Volume Fraction on the Mechanical Properties of Al—SiC Nanocomposites Produced by Mechanical Alloying and Consolidation

Al—(1, 3, 5, 7, 10 vol%) SiC nanocomposites were produced by mechanical alloying (MA) and double pressing/sintering route. The characteristics of the milled powders and the consolidate specimens were examined using high resolution scanning electron microscopy and X-ray diffraction method. Compression and hardness tests were used to study the effect of SiC volume fraction on the strength of Al—SiC nanocomposites. It was shown that with increasing the SiC volume fraction, finer particles with narrower size distribution and smaller crystallite size are obtained after MA. During sintering close to the melting point of aluminum, the presence of nanometer-scaled SiC particles was found to hinder the grain growth significantly. The Al matrix with a higher SiC content exhibited more potential for grain boundary pinning, i.e., smaller grain size was obtained at higher SiC volume fractions. Consequently, an improved mechanical strength was obtained. The processing method (MA/pressing/sintering) can be used for fabrication of near-net shape Al matrix nanocomposites.

WITHDRAWN: Effect of reinforcement volume fraction on the mechanical properties of Al–SiC nanocomposites produced by mechanical alloying and sintering

WITHDRAWN: Effect of reinforcement volume fraction on the mechanical properties of Al–SiC nanocomposites produced by mechanical alloying and sintering

Effect of reinforcement volume fraction on mechanical alloying of Al–SiC nanocomposite powders

Mixtures of aluminium powder and nanoscaled SiC particles (n-SiC) at various volume fractions of 0, 1, 3, 5, 7 and 10 are comilled in a high energy planetary ball mill under an argon atmosphere to produce nanocrystalline Al–SiC nanocomposites. High resolution scanning electron microscopy (HRSEM), X-ray diffraction (XRD) method, laser particle size analysis and powder density measurement were used to study the morphological changes and microstructural evolution occurred during mechanical alloying. Al–SiC composite powder with microscaled SiC particles (1 m m) was also synthesised and characterised to examine the influence of reinforcement particle size on the milling process. It was found that with increasing volume fraction of n-SiC, a finer composite powder with more uniform particle size distribution is obtained. The morphology of the particles also became more equiaxed at shorter milling times. Furthermore, the analysis of XRD patterns by Williamson–Hall method indicated that the crystallite size of the aluminium matrix decreases with increasing reinforcement volume content while the lattice strain changes marginally. As compared with microscaled SiC particles, it appeared that the effect of n-SiC on the milling stages is more pronounced. The results clearly show that the reinforcement particles influence the work hardening and fracture of the metal matrix upon milling, affecting the structural evolution. With decreasing size of the ceramic particles to nanoscale, this influence becomes more pronounced as the surface to volume fraction increases.

Effect of reinforcement volume fraction and size distribution on the tribological behavior of Al-composite/brake pad tribo-couple

Tribological behavior of aluminium matrix composite (AMC)/brake pad tribo-couple under dry sliding conditions was studied using Pin-on-Disc machine. Brake pad material was used as pins while the AMC formed the rotating disc. Series of experiments were performed to characterize the tribological nature of the tribo-couple. Load and sliding speeds were varied over a range to represent actual braking conditions in passenger cars. Effect of volume fraction and size distribution of reinforcement on wear and friction coefficient has been studied. It was observed that a heterogeneous tribo-layer was formed over the worn surfaces during the wear tests. Presence of tribo-layer was believed to cause two effects: acting as a lubricant layer and acting as a source of wear debris. Morphology and topography of worn surfaces and debris were studied using scanning electron microscope (SEM), electron probe micro analyzer (EPMA), and X-ray diffraction (XRD) techniques. When the reinforcement in the matrix has wide size distribution, wear rate and friction coefficients are found to be higher compared to composite containing mono-size reinforcement.

The effect of reinforcement volume fraction and particle size on the mechanical properties of β-tricalcium phosphate–high density polyethylene composites

The mechanical properties of the tricalcium phosphate–high density polyethylene (β-TCP/HDPE) composite samples have been investigated by looking at the effect of particle size and volume fraction of tricalcium phosphate on the fracture strength, modulus of elasticity and failure energy in the composite samples. A decrease in both the fracture strength and failure energy was observed with an increase in the volume fraction of the tricalcium phosphate. Both properties decreased further with the use of larger β-TCP particles. Increase in the tricalcium phosphate content led to an increase in the modulus of elasticity values in the composite samples. However, a lesser increase in modulus of elasticity was observed when larger β-TCP particles were used in the preparation of the composite samples. SEM analysis of the fractured surfaces showed a transition from ductile to brittle type of failure as the volume fraction of the tricalcium phosphate increased in the samples.

Three-dimensional multiparticle cell simulations of deformation and damage in sphere-reinforced composites

The tensile loading of an elasto–plastic matrix reinforced with elastic spheres was studied by means of the three-dimensional finite element analysis of periodic multiparticle cells containing a random dispersion of thirty identical spheres. Damage in the form of void nucleation, growth and coalescence in the matrix was included with the aid of the modified Gurson model. It was found that damage was early localized in regions between spheres closely packed along the deformation axis: the strain concentration in these regions nucleates voids, which grew driven by the tensile hydrostatic stresses. The stress relaxation induced by void nucleation and growth reduced significantly the flow stress of the composite, and eventually a maximum in the stress–strain curves was observed. The multiparticle cell results were compared with those obtained from single-particle axisymmetric simulations, and the effect of reinforcement volume fraction was analyzed as well as that of the matrix damage parameters on the composite behavior.