Particle-reinforced Composites Research Articles

Microstructure, microhardness, and tensile properties of hot-rolled Al6061/TiB2/CeO2 hybrid composites

T1B2 and CeO2 particle-reinforced A16061 hybrid composites were manufactured using stir casting and hot rolling techniques. The base alloy and composites were hot-rolled at 500°C and a 50% reduction was achieved through 12 passes. The effect of varying TB2 and CeO2 particle additions on the microstructure and mechanical properties of the Al6061 matrix was studied. Scanning electron microscopy showed uniform dispersion of both the reinforcements, with good interfacial bonding. Microhardness and tensile properties like yield and tensile strength were found to be higher for hybrid composite with 2.5% TiB2 and 2.5% CeO2 compared to Al6061 alloy and other hybrid composites. The increased tensile strength is attributed to good dispersion and interfacial bonding between the particles and Al6061 matrix. Fracture analysis using a scanning electron microscope revealed ductile fracture for the Al6061 alloy and mixed characteristics of ductile-brittle fracture for hybrid composites.

Droplet Impact-Induced Molten Pool Dynamics and Particle Migration Patterns During TIG-Assisted Droplet Deposition Manufacturing of SiC Particle-Reinforced Al-Si Alloy

A three-dimensional droplet-pool coupled model with dispersed phase (solid SiC particles) was developed to simulate TIG-assisted droplet deposition manufacturing (DDM) of silicon carbide particle-reinforced aluminum matrix composites (AMCs), which was employed to calculate the surface morphology of the deposited layer, the thermal-flow fields and the distribution state of reinforcing particles in the molten pool. The cross-section profile of a single-track SiC-reinforced AMC deposit and the distribution state of reinforcement were examined and compared with the findings predicted by simulation, a good agreement was achieved. It is found that the impacting droplet including the SiC reinforcement creates an obvious crater within the molten pool. The viscous damping and simultaneous solidification are the main factors that dissipate the kinetic energy of the droplet. In addition, we discuss quantitatively how impact-induced thermodynamic within molten pool can change the migration behavior and distribution state of SiC reinforcement. The non-homogeneous distribution of the particles can be attributed to the thermocapillary micro-convection and the velocity difference in the spreading and recoiling stages.

Analysis and Optimization of the Machining Characteristics of High-Volume Content SiCp/Al Composite in Wire Electrical Discharge Machining

With the properties of high specific strength, small thermal expansion and good abrasive resistance, the particle-reinforced aluminum matrix composite is widely used in the fields of aerospace, automobile and electronic communications, etc. However, the cutting performance of the particle-reinforced aluminum matrix composite is very poor due to severe tool wear and low machining efficiency. Wire electrical discharge machining has been proven to be a good machining method for conductive material with any hardness. Even so, the high-volume SiCp/Al content composite is still a difficult-to-machine material in wire electrical discharge machining due to the influence of insulative the SiC particle. The goal of this paper is to analyze the machining characteristics and find the optimal process parameters for the high-volume content (65 vol.%) SiCp/Al composite in wire electrical discharge machining. Experimental results show that the material removal method of the SiCp/Al composite includes sublimating, decomposing and particle shedding. The material removal rate is found to increase with the increasing pulse-on time, first increasing and then decreasing with the increasing pulse-off time, servo voltage, wire feed and wire tension. Pulse-on time and servo voltage are the dominant factors for surface roughness. In addition, the multi-objective optimization method of the nondominated neighbor immune algorithm is presented to optimize the process parameters for a fast material removal rate and low surface roughness. The optimized process parameters can increase the material removal rate by 34% and reduce the surface roughness by 6%. Furthermore, the effectiveness of the Pareto optimal solution is proven by the verified experiment.

On the Hardness and Elastic Modulus of Phases in SiC-Reinforced Al Composite: Role of La and Ce Addition.

The use of silicon carbide particles (SiCp) as reinforcement in aluminium (Al)-based composites (Al/SiCp) can offer high hardness and high stiffness. The rare-earth elements like lanthanum (La) and cerium (Ce) and transition metals like nickel (Ni) and copper (Cu) were added into the matrix to form intermetallic phases; this is one way to improve the mechanical property of the composite at elevated temperatures. The α-Al15(Fe,Mn)3Si2, Al20(La,Ce)Ti2, and Al11(La,Ce)3, π-Al8FeMg3Si6 phases are formed. Nanoindentation was employed to measure the hardness and elastic modulus of the phases formed in the composite alloys. The rule of mixture was used to predict the modulus of the matrix alloys. The Halpin–Tsai model was applied to calculate the elastic modulus of the particle-reinforced composites. The transition metals (Ni and Cu) and rare-earth elements (La and Ce) determined a 5–15% increase of the elastic modulus of the matrix alloy. The SiC particles increased the elastic modulus of the matrix alloy by 10–15% in composite materials.

Representative volume elements for matrix-inclusion composites - a computational study on the effects of an improper treatment of particles intersecting the boundary and the benefits of periodizing the ensemble

We investigate volume-element sampling strategies for the stochastic homogenization of particle-reinforced composites and show, via computational experiments, that an improper treatment of particles intersecting the boundary of the computational cell may affect the accuracy of the computed effective properties. Motivated by recent results on a superior convergence rate of the systematic error for periodized ensembles compared to taking snapshots of ensembles, we conduct computational experiments for microstructures with circular, spherical and cylindrical inclusions and monitor the systematic errors in the effective thermal conductivity for snapshots of ensembles compared to working with microstructures sampled from periodized ensembles.We observe that the standard deviation of the apparent properties computed on microstructures sampled from the periodized ensembles decays at the scaling expected from the central limit theorem. In contrast, the standard deviation for the snapshot ensembles shows an inferior decay rate at high filler content. The latter effect is caused by additional long-range correlations that necessarily appear in particle-reinforced composites at high, industrially relevant, volume fractions. Periodized ensembles, however, appear to be less affected by these correlations.Our findings provide guidelines for working with digital volume images of material microstructures and the design of representative volume elements for computational homogenization.

Calcium hydroxyapatite nanoparticles as a reinforcement filler in dental resin nanocomposite

The current study focuses on the fabrication of calcium hydroxyapatite (Ca10(PO4)6(OH)2) (HA) in a nanorange having whiskers- and cubic-shaped uniform particle morphology. The synthesized HA particles hold a promising feature as reinforcement fillers in dental acrylic resin composite. They increase the efficacy of reinforcement by length and aspect ratio, uniformity, and monodispersity. Therefore, the acrylic resin was reinforced with the as-synthesized monodispersed HA filler particles (0.2–1 Wt%). The presence of filler particles in the composite had a noticeable effect on the tribological and mechanical properties of the dental material. The morphological effect of HA particles on these properties was also investigated, revealing that cubic-shaped particles showed better results than whiskers. The as-fabricated composite (0.4 Wt%) of the cubic-shaped filler particles showed maximum hardness and improved antiwear/antifriction properties. Particle loading played its part in determining the optimum condition, whereas particle size also influenced the reinforcement efficiency. The current study revealed that particle morphology, particle size, uniformity, etc., of HA fillers, greatly influenced the tribological and mechanical properties of the acrylic resin-based nanocomposite. Improvement in the tribological properties of HA particle-reinforced acrylic resin composites (HA–acrylic resin) followed the trend as AR < CmC < WC < CC.

Effect of stress concentration and deformation temperature on the tensile property and damage behavior of a B4Cp/Al composite

In the present work, the influence of stress concentration and deformation temperature on the mechanical behavior of boron carbide particles reinforced aluminum matrix (B4Cp/Al) composites fabricated by powder metallurgy was investigated via the tensile test and finite element simulation based on the real microstructure. The results demonstrate that a uniform particle distribution and a good interface bonding between the particles and matrix are found in the 5 wt% B4Cp/6061Al composite. When the deformation temperature decreases from 298 to 77 K, the tensile property and notch sensitivity ratio of the notched composite increases. Combined with the microstructure observation and stress/strain evolution, the fracture mechanism of the notched composite at 77 K was revealed. Specifically, there is a difference in stress and strain distributions induced by deformation temperature in the initial stage of deformation of the notched composite. The matrix damage tends to occur from the notch and propagate to the high strain regions near the particles. Furthermore, there is a high possibility of particle fracture or interface debonding in the notched composite due to the high matrix stress at 77 K. This work provides the experimental and theoretical basis for the application of particle-reinforced aluminum matrix composites with stress concentration under cryogenic environments.

Research on chip formation mechanism and surface morphology of particle-reinforced metal matrix composites

In this paper, a finite element (FE) cutting model for particle-reinforced metal matrix composites (PRMMCs) considering material damage was developed to predict SiC particle failure, cutting forces, and machined surface topography in SiCp/Al composite machining, and to analyze the dynamic mechanisms of chip formation and particle failure evolution. The validity of the simulation model was verified by comparing the simulation results with the cutting forces and surface topography obtained from the milling machining experiments. It was found that complex stress-strain fields exist in SiCp/Al composites with mesoscopic non-homogeneous structures, and alternating reticulation of tensile and compressive stress between particles was observed; particle failure due to tool-workpiece interaction exists in both direct and indirect ways; particle failure and local chip deformation during machining affect surface topography and chip shaping, resulting in serrated chips, pitting on the machined surface, and residual particle fragments.

Evolution of Residual Stresses and Fracture in Thermomechanically Loaded Particle-Reinforced Metal Matrix Composites

Evolution of Residual Stresses and Fracture in Thermomechanically Loaded Particle-Reinforced Metal Matrix Composites

Synthesis of nano- to micrometer-sized B4C particle-reinforced aluminum matrix composites via powder metallurgy and subsequent heat treatment

Synthesis of nano- to micrometer-sized B4C particle-reinforced aluminum matrix composites via powder metallurgy and subsequent heat treatment

Micromechanics-based simulation of anisotropic magneto-mechanical properties of magnetorheological elastomers with chained microstructures

Magnetorheological elastomers (MREs) are ferromagnetic particle-reinforced composites that have a wide application prospect in engineering because of their tunable stiffness with applied magnetic fields. While a large number of experimental efforts have been carried out to characterize the magneto-mechanical properties of MREs, few physics-based quantitative modeling and simulation have been explored. Here a micromechanics-based finite element model and computational homogenization is developed to determine the field-dependent shear moduli of MREs. The magneto-elastic coupling is realized with the magnetic field-induced body forces in the local mechanical field. The three-dimensional body forces are solved with consideration of magnetization and demagnetizing fields. Effects of essential microstructure parameters (particle concentration and particle spacing) are investigated on the effective magneto-mechanical properties of chain-structured MREs. The numerical results demonstrate that the microstructures and demagnetizing field have significant effects on the field-induced moduli of MREs. RVEs with appropriate microstructures are selected to compare our model predictions of magneto-mechanical properties with multiple groups of experiment data in the literature, showing the capability and validity of the proposed model.

Mechanism of an approach based on bone microstructure to improve the machining quality for bionic multi-size particulate-reinforced composite

The microstructure of composites is one of the core factors affecting the machining quality of composites. However, the underlying mechanism is still unclear. Therefore, the research on the relationship could point out the clear direction for producing composites with remarkable processability. Inspired by the function of bone microstructure to disperse stress, a multi-size particulate-reinforced composites model was proposed to produce advanced composites with better processing performance here. Concurrently, this research used the GaussAmp function to construct SiCp/Al composites with a different particle size distribution, and systematically study their mechanical properties and processing quality. The results show that the machining quality of the SiCp/Al composites could be greatly improved when the particle size distribution conforms to the right side of the GaussAmp function. This conclusion could contribute to select the particle size and content of reinforcing material accurately during machining of composites, and has far-reaching guiding significance for improving the properties and machining quality of particulate-reinforced composites.

Fabrication of particle-reinforced aluminum alloy composite: role of casting and rolling

ABSTRACT In this study, Al0.5CoCrFeNi high-entropy alloy particles (HEAp) were added to aluminum alloy 2024 to prepare aluminum alloy matrix composites. The composites were prepared via melting, casting, and subsequent rolling (hot rolling, cold rolling, or cryorolling). The results reveal that the adding of HEAp can significantly refine the grains during casting. The cryorolled AA2024 matrix composite with 1 weight percent HEAp content had a tensile strength of 543 MPa and 10% elongation. The Al-Cu crystalline phase of the aluminum matrix composites was more finely dispersed after the addition of an appropriate HEAp content and cryorolling, which led to an increase in both strength and ductility.

Homogenization of Composites with Extended General interfaces: Comprehensive Review and Unified Modeling

Abstract Interphase regions that form in heterogeneous materials through various underlying mechanisms such as poor mechanical or chemical adherence, roughness, and coating, play a crucial role in the response of the medium. A well- established strategy to capture a finite-thickness interphase behavior is to replace it with a zero-thickness interface model characterized by its own displacement and/or traction jumps, resulting in different interface models. The contributions to date dealing with interfaces commonly assume that the interface is located in the middle of its corresponding interphase. We revisit this assumption and introduce a universal interface model, wherein a unifying approach to the homogenization of heterogeneous materials embedding interfaces between their constituents is developed. The proposed novel interface model is universal in the sense that it can recover any of the classical interface models. Next, via incorporating this universal interface model into homogenization, we develop bounds and estimates for the overall moduli of fiber-reinforced and particle-reinforced composites as functions of the interface position and properties. Furthermore, we elaborate on the computational implications of this interface model. Finally, we carry out a comprehensive numerical study to highlight the influence of interface position, stiffness ratio and interface parameters on the overall properties of composites, where an excellent agreement between the analytical and computational results is observed. The developed interface-enhanced homogenization framework also successfully captures size effects, which are immediately relevant to emerging applications of nano-composites due their pronounced interface effects at small scales.

Understanding the Mechanical Reinforcement of Metal-Organic Framework-Polymer Composites: The Effect of Aspect Ratio.

The aspect ratio (AR) of filler particles is one of the most critical determinants for the mechanical properties of particle-reinforced polymer composites. However, it has been challenging to solely study the effect of particle AR due to the difficulties of controlling AR without altering the physical and chemical properties of the particle. Herein, we synthesized PCN-222, a zirconium-based porphyrinic metal-organic framework (MOF) with preferential longitudinal growth as a series of particles with ARs increasing from 3.4 to 54. The synthetic MOF conditions allowed for the chemical properties of the particles to remain constant over the series. The particles were employed as reinforcers for poly(methyl methacrylate) (PMMA). MOF-polymer composite films were fabricated using doctor-blading techniques, which facilitated particle dispersion and alignment in the PMMA matrix, as revealed by optical microscopy and wide-angle X-ray diffraction. Mechanical measurements showed that both elastic and dynamic moduli increased with particle AR and particle concentrations but started to decrease as particle loading increased beyond 0.5 wt % (1.12 vol %). The data obtained at low particle loadings were fitted well with the Halpin-Tsai model. In contrast, the percolation model and the Cox model were unable to adequately fit the data, indicating the mechanical reinforcement in our system mainly originated from efficient load transfer between particles and the matrix in the particle orienting direction. Finally, we showed that the thermal stability of composite films increased with the addition of MOF particles because of the high thermal degradation temperature and restricted polymer chain mobility.

Research progress of ceramic particles reinforced Al-based composites with micro-nano-scale and high volume fraction

Al-based composites reinforced by high volume fraction ceramic particles have attracted much attention because of their high specific strength, high specific modulus, good wear resistance, and low thermal expansion properties. The preparation technology, advantages, and disadvantages of Al-based composites reinforced by high ceramic content are reviewed in this study. The research status of the microstructure and mechanical properties of Al-based composites reinforced by high ceramic particles content is summarized. The effects of ceramic content and preparation technology on the properties of Al-based composites are described. The strengthening mechanism of micro-nano-scale ceramic particles in composites is also expounded. The development trend of micro-nano-scale high content ceramic particle-reinforced Al-based composites is prospected.

Numerical Analysis of Particulate Migration Behavior within Molten Pool during TIG-Assisted Droplet Deposition Manufacturing of SiC Particle-Reinforced Aluminum Matrix Composites.

A transient three-dimensional (3D) numerical model was established to illustrate the heat transfer, fluid flow and particle migration behaviors in the molten pool during TIG-assisted droplet deposition manufacturing (DDM) of SiC particle-reinforced aluminum matrix composites (AMCs). The effect of temperature-dependent physical properties and the interaction between the SiC reinforcement and the liquid metal matrix were considered. A double-ellipsoidal volumetric heat source model was adopted to simulate the energy interactions between the pulse square-wave variable polarity TIG welding arc and the moving substrate. Free surface fluctuations of molten pool due to arc force and sequential droplet impact are calculated with volume of fluid (VOF) method in a fixed Eulerian structured mesh. The numerical model, capable of capturing the impact, simultaneous spread, and phase change of the droplets as well as the motion trajectory and terminate distribution state of the reinforcement particles, is key tool to understand the formation mechanism of the TIG-assisted DDM of SiC particle-reinforced AMCs. The numerical model was validated by the metallographic observations, and the calculated particle distribution and solidification morphology of deposited layer agree well with the experimental measurements.

Comparison of the effects of Mg and Zn on the interface mismatch and compression properties of 50 vol% TiB2/Al composites

Low ductility limits the extensive application of high volume fraction (>30 vol%) ceramic particle-reinforced metal matrix composites, and the simultaneous improvement of strength and ductility is still a challenge owing to the smaller amount of matrix contained in such composites. In this paper, the effects of various contents of Mg or Zn (0, 6, 10 and 14 wt%) on the interface mismatch and compression properties of 50 vol% TiB2/Al composite fabricated in situ are comparatively studied. The results indicate that Mg has a better refinement effect than Zn on the TiB2 ceramic particles. Mg can reduce the crystallographic mismatch degree of the Al/TiB2 interface. 6 wt% Mg simultaneously increases the σ0.2, σUCS and εf of the composite into 780 MPa, 1162 MPa and 10.68%, compared with the composite without the addition of Mg, increasing 8.5%, 2.8% and 30.6%, respectively. However, the addition of Zn leads to serious distortion of the Al lattice and deteriorates the interface matching degree of Al/TiB2, so the addition of Zn generally improves the σ0.2 and σUCS while sacrifices the plasticity simultaneously. Furthermore, the contributions of various strengthening mechanisms of the matrix in the high volume fraction TiB2/Al composites are analyzed through a comparative study.

Effect of local reinforcement particle distribution on mechanical properties of in-situ TiB/TiC1-x particle reinforced Ti-5Al-5Mo-5V-3Cr – comparison between model and experiment

In-situ TiB and TiC1-x particle-reinforced titanium matrix composites (TMCs) based on a near-β Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) reacting chemically with 4 vol.-% B4C were processed by spark plasma sintering (SPS). Different local distributions of the reinforcement particles formed within the composite were adjusted by varying the conditions during powder preparation. The measured Young’s modulus, hardness and compressive yield strength of the composites increased, as the reinforcement particles were distributed more homogeneously within the matrix. In addition, Young’s modulus and hardness were modelled considering the hybrid TiB-whisker and TiC-particle reinforcement applying the rule of hybrid mixtures (RoHM) and the Fu-method, respectively. The compressive yield strength was modelled in ac-cordance with the summation of the particular effective strengthening mechanisms and the Clyne-method. Measured values of the Young’s modulus and the hardness were overestimated by the modelling as the clustering of the reinforcement particles increased. The compressive yield strength of the composites is modelled appropriately using the Clyne-method. However, pronounced agglomeration of the reinforcing particles within the matrix resulted in an overesti-mation of the measured values.

Micromechanical model of linear viscoelastic particle-reinforced composites with interphase

In this paper, a micromechanics-based constitutive model is proposed for linear viscoelastic particle-reinforced composites with interphase based on the theoretical homogenization framework in the time domain that we recently proposed for viscoelastic composites. All the composite's phases (i.e., the matrix, particle and interphase) are considered as linear viscoelastic materials, whose constitutive responses are governed by the general Maxwell model. The interphase with varying viscoelastic property is approximated by the multiple homogenized layers. The constitutive model of the composites is multiplicatively decomposed as two parts: (1) the effective relaxation function characterizes the time-dependent behaviors, and (2) the referred elastic part refers to the long-term responses. The classical composite-sphere model and three-phase model are extended to derive the variables involved in the constitutive model for the bulk and shear behaviors, respectively. The comprehensive numerical simulations, including the effects of the number of interphase layer, interphase thickness, particle content and loading condition, are carried out to validate the proposed constitutive model. The results reveal that the constitutive model can predict well the viscoelastic behaviors of the particle-reinforced composites with interphase. The validated constitutive model is then applied to identify the viscoelastic properties of the interphase by fitting the predictive results and the experimental data of the “overall” composites. The results show the good consistency for the interphase properties between the theoretical identification and the experimental observation. The discussion of the interphase percolation is then carried out, and the findings demonstrate again that the constitutive model can also give good predictions under the percolation situation.