Discontinuous Metal Matrix Composites Research Articles

Exploring the design space of discontinuous metal matrix composites through domain-knowledge enhanced machine learning

Tailored reinforcement architectures in discontinuous metal matrix composites (DMMCs) offer superior mechanical performance with broad scientific and financial interests. This study presents a domain-knowledge enhanced machine learning approach to efficiently explore the design space of Al-SiC DMMCs for optimization. A substantial dataset containing 140,000 instances, resembling characteristic reinforcement configurations and variants, is generated using a series of algorithms. Employing high-throughput finite element analysis, the elastic properties of each configuration are estimated. Statistical analysis reveals that a more homogeneous distributed reinforcement contributes to mechanical stability, whereas configurations with extreme performance tend to have inhomogeneous reinforcement distribution. A deep residual neural network trained on this dataset accurately learns the structure-property correlations. Coupled with a genetic algorithm, the framework identifies optimal configurations across different volume fractions for maximizing/minimizing properties including tensile modulus, shear modulus, and Poisson's ratio. Comparative analysis shows the incorporation of domain knowledge improves data quality, facilitating more effective design space exploration. This study contributes to advancing composite materials design, particularly for next-generation high-performance DMMCs.

Strength-ductility synergy in 3D-printed (TiB + TiC)/Ti6Al4V composites with unique dual-heterogeneous structure

The 3D-printed (TiB + TiC)/Ti6Al4V composite with tailored network reinforcement architecture and heterogeneous α lamellae structure (i.e., a dual-heterogeneous structure) possesses simultaneously improved tensile strength and uniform ductility. To reveal the fundamentals behind the strengthening and deformation mechanisms, the microstructural evolution and tensile deformation behavior of as-printed (TiB + TiC)/Ti6Al4V composite were carefully examined under in-situ tensile testing together with as-printed Ti6Al4V. The heterogeneous structure in the composites induced significant constraint effect, affording deformation compatibility via strain partitioning throughout the composite. Importantly, owing to the heterogeneous α lamellae structure and the pinning effect of reinforcements, the hetero-deformation induced additional strengthening effect and strain-hardening potential, leading to much enhanced plastic deformation capacity and improved strengthening efficiency. Furthermore, the microcracks arresting stabilized the plastic deformation at the later deformation stage and offered extra ductility. Based on these investigations, the intrinsic strengthening and deformation mechanisms behind the synergetic strength-ductility over the whole deformation process were elucidated. This work highlights the importance of heterogeneous structure design strategy in the development of discontinuous metal matrix composites.

Analytical and Numerical Analysis of Extrusion Force, Stress and Strain Development During Extrusion Al6063-SiC Composite

Nowadays composite material are highly interesting in different areas like, aerospace, thermal management, automotive application, and electronic products etc. Aluminium based metal matrix with silicon carbide as particle reinforcements called discontinuous reinforced metal matrix composite materials. It has excellent mechanical properties like high yield strength, wear resistance, corrosion resistance and vibration resistance. During the development of discontinuous reinforcement metal matrix composites compression process like, extrusion is an advisable secondary process for homogenous distribution of the reinforcement’s materials through the metal matrix. This research was investigated the metal flow behavior of extrusion load, stress and strain distribution of Al6063/Sic based discontinuous reinforcement metal matrix composite. The billets extruded from round billet to square shape and are used for different applications. Third order polynomial and cosine die profiles were used as extrusion dies for this research by taking 30%, 60% and 90% area reductions. Depends on these three different area reductions upper bound and DEFORM 3D finite element analysis method were used to analyze analytically and numerically respectively. Due to these different area reductions, the extrusion load was minimum in cosine die profiles both analytical and numerical results. In 30% of area reduction cosine die profile has optimum load (878.59N) and it used to extrude Al6063/20%SiC composite billet materials from 20mm input diameter to 14.8x14.8mm output square sides. Therefore, 30% area reduction cosine die profile has minimum extrusion load as compare other area reduction of cosine die and 3rd order polynomial dies. It is used as extrusion die for Al6063/SiC composite materials to optimum extrusion loads in different % of area reduction of square shape extruded.

Fracture behaviour of SiCp/Al composites with network architecture

It is found that, for discontinuous metal matrix composites (MMCs) with an inhomogeneous network reinforcement distribution, a thin network layer and large alloy cells are favorable for the toughness.. The network layers contribute to the high modulus and strength, while large alloy cells work in deflecting crack propagation and thus enhancing the toughness. Furthermore, mutually coordinated and restricted deformation behaviors of alloy cells may create a three-dimensional tensile stress state, which induces the anomalous brittle fracture of intrinsically ductile aluminum matrix in some alloy cells. These phenomena have weakened the matrix alloy plastic deformation capacity, constrained the crack propagation and improved the toughness of network composites.

Fabrication of Nano Hybrid Metal Matrix Composites through Stir Casting Route: A Review

Nanocomposite are the most promising advance multi-phase material, having nano particles in its composition within its structure (size being less than 100 nm) and contain at least one phase with constituents in the Nano-meter size range. The properties of nanocomposites are controlled by the type/size of the reinforcement/nature of bonding and type of processing method. Among the various processes of manufacturing prevalent for discontinuous nano hybrid metal matrix composites, particularly stir casting is accepted as a favorable method, which is also commercially viable. Stir casting is advantageous for mass production of composites for being simple and flexible in nature along with cost effectiveness. As it is low-cost comparably and also offers wide selection of materials. Further, it produces better bonding of reinforcements with the matrix, due to the uniform stirring action.

Method of stir casting of Aluminum metal matrix Composites: A review

Among the variety of manufacturing processes available for discontinuous metal matrix composites, stir casting is generally accepted as a particularly promising route, currently practiced commercially. Its advantages lie in its simplicity, flexibility and applicability to large quantity production with cost advantage. The major problem of this process is to obtain sufficient wetting of particle by liquid metal and to get a homogenous dispersion of the particulates. The present review is on the method employed in stir casting such as, how the base metal is melted, at what temperature and state it is to be maintained, what conditions the particulates are added and how the stirring time and stirring speed affect the final composite material. The effect of stirrer design and feeding mechanism has also been discussed. The variation in the type of mixing the particulates into the metal matrix has also been dealt with in the paper. In the introductory part the stir casting methodology with a diagram has been laid out to give an overview of the overall process of casting of metal matrix composites. The limitations of the process are also listed in the paper.

Effects of Dispersoids on Wear Behavior of Cu-Based Nanocomposite Containing SiO2 Nanoparticles

Solid particles in discontinuous reinforcement metal matrix composites (DRMMCs) drastically improve their strength. Since the strength of DRMMCs is improved by the Orowan mechanism, smaller particles, such as nanoparticles, are effective as dispersoids. In this study, the effects of nanoparticles on the sliding wear behavior of DRMMCs are investigated using Cu-based composites containing 0.6, 1.2, and 1.7 vol % SiO2 particles. Wear resistance of the Cu–SiO2 composite is improved by increasing the volume fraction of SiO2 particles. Moreover, the amount of wear for the Cu–SiO2 composites increases with increasing sliding distance and then becomes saturated beyond about 1000 m. Vickers hardness for all specimens becomes the same regardless of the volume fraction of SiO2 particles as the sliding distance increases. This behavior can be explained by the work-hardening rate of the Cu matrix and the critical hardness for adhesion with a counter-material. It is found that nanoparticles in DRMMCs improve wear resistance by increasing the work-hardening rate of the metal matrix.

Cyclic Stress-Strain Behavior and Thermomechanical Effect in Metal Matrix Composites

A micromechanical model based on continuum analysis has been investigated by using finite element analysis (FEA) in discontinuous metal matrix composites (DMMC). To assess the tensile and compressive constitutive responses, a cyclic stress-strain behavior has been performed. For analysis procedure, the elastoplastic FEA and the regularly aligned axisymmetric single fiber model have been implemented to evaluate the internal field quantities. Accordingly, the fiber and matrix internal stresses were investigated for the constrained representative volume element (RVE). Further, the local plasticity in the matrix were described during loading and unloading precesses, which can predict the damage mechanisms as well as strengthening mechanisms. On the other hand, a thermoelasto- plastic analysis has been performed using FEA for the application to the continuum behavior in a discontinuous metal matrix composite. The internal field quantities of composite as well as overall composite behavior and an experiment was demonstrated to compare with the numerical simulation. As the procedure, the reasonably optimized FE mesh generations, the appropriate imposition of boundary conditions, and the relevant postprocessing such as elasto-plastic thermo-mechanical analysis were taken into account. For micromechanical model, the temperature dependent material properties and precipitation hardening effects have been employed to investigate field quantities. It was found that the residual stresses are induced substantially by the temperature drop during heat treatment and that the FEA results give a good agreement with experimental data.

518 不連続強化型金属基複合材料の熱サイクル超塑性に関する微視力学的研究

518 不連続強化型金属基複合材料の熱サイクル超塑性に関する微視力学的研究

Effect of Equal Channel Angular Pressing on the Distribution of Reinforcements in the Discontinuous Metal Matrix Composites

The 6061 Al–10 vol% SiCw composites were prepared by powder metallurgy with the powders having the different sizes, i.e. <30 \\micron and 30 \\micron<. The composites were subjected to equal channel angular pressing (ECAP) under various conditions and the microstuctural changes during ECAP were examined. A special focus was made on the effect of ECAP conditions on the distribution of SiC whiskers. The present investigation was aimed at exploring the feasibility of ECAP as a post working process for manufacturing the discontinuous metal matrix composites. The microstructural examination and the microhardness measurement of the ECAPed samples suggested that the optimum combination of the uniform microstructure and enhanced mechanical properties would be obtained by (a) using the powders having the smaller size, (b) decreasing ECAP temperature, and (c) repeating ECAP.

Interfacial Stresses and Void Nucleation in Discontinuously Reinforced Composites

This paper presents the theoretical predictions of the stress state at the inclusion-matrix interface in discontinuous metal matrix composites by the generalized inclusion method. In the author’s previous works, this method had been extended to the elastoplastic deformation in the matrix material. The present analysis of the ellipsoidal inclusion problem indicates that the regions at the pole and the equator of the particle/matrix interface essentially remain elastic regardless of the level of deformation, although the size of the elastic region keeps decreasing as deformation becomes larger. It was also found that, when the composite is undergoing a relatively large plastic deformation (strain), the maximum interfacial normal stress is approximately linearly dependent upon the von Mises stress and the hydrostatic stress. Based on the stress criterion for void nucleation, the author determined the void nucleation loci and nucleation strain for a composite subjected to an axisymmetric macroscopic stress state. The influence of interfacial bonding strength, inclusion shape, and volume fraction on the occurrence of void nucleation have been determined. The interfacial bonding strength in a SiC-aluminum system was re-evaluated by using existing experimental evidence. [S0094-4289(00)01301-3]

Creep behavior in an Al-Fe-V-Si alloy and SiC whisker-reinforced Al-Fe-V-Si composite

High temperature strengthening mechanisms in discontinuous metal matrix composites were examined by performing a close comparison between the creep behavior of 15vol. pct SiCw/8009Al and that of its matrix alloy, 8009Al. Both the alloy and composite exhibit a single-slope behavior with anomalously high values of apparent stress exponent and high apparent activation energy. The presence of SiC whiskers does not remarkably influence these two kinds of dependence of creep rates but reduces the creep rates by about two orders of magnitude. Transmission electron microscopy examination of the deformation microstructure reveals the occurrence of attractive dislocation/particle interaction. The creep data were analyzed by the threshold stress approach and by the dislocation-climb theories based on attractive interaction between dislocations and dispersoids. All data can be rationalized by a power-law with a stress exponent of 5 and a creep activation energy close to that for the self-diffusion in aluminum. The threshold stress decreases linearly with increasing temperature. General climb together with the attractive but not strong interactions between the dislocations and dispersoids is suggested to be the operative deformation mechanism. The contribution of SiC whiskers to the creep strength of 8009 Al composite can be evaluated quantitatively when the shear-lag model is applied. However, the effects of whisker length and whisker orientation distributions must be considered. Two probability density functions are used for modelling the distribution of whisker length and whisker orientation.

Structural performance of discontinuous metal matrix composites

Discontinuous metal matrix composites (i.e. short fibre and particle reinforced materials) have attained a significant degree of scientific and technological maturity as advanced structural materials. Initial commercialisation has been achieved, with the unique combinations of mechanical and physical properties afforded by metal-ceramic systems proving appropriate for a variety of structural and semistructural applications. In recent years there has been important consolidation in the understanding of basic structural properties in such composites, which are addressed in the present review. The outstanding requirement for an improved understanding of damage tolerance characteristics in these materials is particularly noted. ‘Mesoscopic’ materials architectures (e.g. laminated and functionally graded materials) are also discussed, and the associated potential for development offracture resistant discontinuous metal composite materials highlighted.

Structural performance of discontinuous metal matrix composites

Structural performance of discontinuous metal matrix composites

Creep strengthening in a discontinuous SiC-Al composite

High-temperature strengthening mechanisms in discontinuous metal matrix composites were examined by performing a close comparison between the creep behavior of 30 vol pct SiC-6061 Al and that of its matrix alloy, 6061 Al. Both materials were prepared by powder metallurgy techniques. The experimental data show that the creep behavior of the composite is similar to that of the alloy in regard to the high apparent stress exponent and its variation with the applied stress and the strong temperature dependence of creep rate. By contrast, the data reveal that there are two main differences in creep behavior between the composite and the alloy: the creep rates of the composite are more than one order of magnitude slower than those of the alloy, and the activation energy for creep in the composite is higher than that in the alloy. Analysis of the experimental data indicates that these similarities and differences in creep behavior can be explained in terms of two independent strengthening processes that are related to (a) the existence of a temperature-dependent threshold stress for creep, τ0, in both materials and (b) the occurrence of temperature dependent load transfer from the creeping matrix (6061 Al) to the reinforcement (SiC). This finding is illustrated by two results. First, the high apparent activation energies for creep in the composite are corrected to a value near the true activation energy for creep in the unreinforced alloy (160 kJ/mole) by considering the temperature dependence of the shear modulus, the threshold stress, and the load transfer. Second, the normalized creep data of the composite fall very close to those of the alloy when the contribution of load transfer to composite strengthening is incorporated in a creep power law in which the applied stress is replaced by the effective stress, the stress exponent,n, equals 5, and the true activation energy for creep in the composite,Q c , is equal to that in the alloy.

Postbuckling analysis of laminated plates made of discontinuous metal matrix composites

The moderately large deflection response of laminated plates that are made of discontinuous metal matrix composites and are subjected to compressive in-plane loading, is addressed. Whisker-, particulate-, and plateletreinforced structures are considered. At each loading increment, a micromechanical analysis is performed to provide the overall instantaneous elastic-viscoplastic behaviour of the metal matrix composite. This is followed by a structural analysis which yields the response of a geometrically imperfect composite plate to applied external loading. Results are presented for simply supported unidirectional and antisymmetric angle-ply SiC/Al plates, subjected to uniaxial compression, for two types of in-plane boundary conditions at unloaded edges. The effects of length-to-thickness ratio, fiber orientation angle, and temperature are illustrated. For all the cases considered, the corresponding behavior of continuous fiber SiC/Al plate with the same volume fraction is shown. Comparisons with the results, obtained by neglecting the viscoplastic effects of the metallic matrix, are presented.

Effect of test conditions on cavitation and failure during tensile loading of discontinuous metal matrix composites

The effect of test temperature and reinforcement shape on cavitation is investigated for commercial purity Al–Al2O3 composite produced via either a powder route or squeeze infiltrationfollowed by extrusion. At room temperature, voids form at the reinforcement/matrix interface. Voids are favoured by reinforcement elongation and planar surfaces normal to the applied stress. Angularities themselves are not favoured sites for cavitation. Increasing the test temperature delays the onset of cavitation and angularities become favoured void nucleation sites. At higher temperature, necking begins to occur at much lower plastic strains, resulting in lower strains to failure, suggesting that void stability is reduced by increasing the temperature. Finite element calculations have been performed to investigate the component of the matrix stress which is responsible for the onset of cavitation in these materials. Results suggest that cavitation is stimulated by the attainment of a critical value of the hydrostatic stress at the interface, rather than of the interfacial normal stress.MST/3029

Effect of test conditions on cavitation and failure during tensile loading of discontinuous metal matrix composites

Abstract The effect of test temperature and reinforcement shape on cavitation is investigated for commercial purity Al–Al2O3 composite produced via either a powder route or squeeze infiltrationfollowed by extrusion. At room temperature, voids form at the reinforcement/matrix interface. Voids are favoured by reinforcement elongation and planar surfaces normal to the applied stress. Angularities themselves are not favoured sites for cavitation. Increasing the test temperature delays the onset of cavitation and angularities become favoured void nucleation sites. At higher temperature, necking begins to occur at much lower plastic strains, resulting in lower strains to failure, suggesting that void stability is reduced by increasing the temperature. Finite element calculations have been performed to investigate the component of the matrix stress which is responsible for the onset of cavitation in these materials. Results suggest that cavitation is stimulated by the attainment of a critical value of the hydros...

Is creep in discontinuous metal matrix composites lattice diffusion controlled?

Creep data for two discontinuous metal matrix composites, namely 3OSiC p-Al particulate and 26(Al 2O 3) f-Al-5Mg short-fibre composites, were analysed to establish whether their creep is matrix lattice diffusion controlled. It was found that ϵ ̇ m 1 n ( ϵ ̇ m is the minimum creep rate) varies with applied stress σ linearly when the true stress exponent n is set equal to 5. For both composites, the threshold stress σ TH was found to decrease rather strongly with increasing temperature. Good correlation of ϵ ̇ m /D L with ( σ- σ TH)/ G D L is the coefficient of lattice diffusion and G is the shear modulus) for both composites strongly suggests matrix lattice diffusion as the creep-rate-controlling process. However, the origin of threshold stress has not been identified and thus its temperature dependence has not been accounted for. Knowing σ TH as a function of temperature and applying a proper consititutive equation of creep, the apparent activation energy of creep Q c and the stress sensitivity parameter of creep rate m were calculated as functions of applied stress and temperature. These Q c calc and m calc were then compared with Q c exp and m exp following from ϵ ̇ = ϵ ̇ m (σ, T) relations as determined experimentally. While for the 3OSiC p-Al composite the agreement was found to be good, this was not the case for the 26(Al 2O 3) f-Al-5Mg composite.

Strengthening and Deformation Mechanisms of Discontinuous Metal Matrix Composites

Strengthening and Deformation Mechanisms of Discontinuous Metal Matrix Composites