Reinforced Metal Matrix Composites Research Articles

Observing and Modeling the Wear Process of Heterogeneous Interface.

Understanding and controlling the wear process of heterogeneous interfaces between soft and hard phases is crucial for designing and fabricating materials, such as improving the wear resistance of particle reinforced metal matrix composites and the accuracy and efficiency of chemical mechanical polishing. However, the wear process can be hardly observed, as interfaces are buried under the surface. Here, we proposed a nanowear test method by combining focused ion beam cutting to expose interfaces, atomic force microscopy to rub against interfaces, and scanning electron microscope to characterize the interface damage. Using this method, three typical wear forms had been observed in Al/SiC composite, i.e., merely matrix wear, particle fracture, and particle pullout. A theoretical model was proposed that revealed that the increasing interfacial friction would induce particle fracture or pullout, depending on the particle edge angle and tip edge angle. This work sheds light on wear control in composites and nanofabrication.

Interatomic potentials for graphene reinforced metal composites: Optimal choice

Graphene reinforced metal matrix composites represent a promising class of materials for high-strength surface coatings because of their high strength and ductility. This study reports the application of different interatomic potentials to correctly describe the interaction between graphene and metals (Al, Cu, Ni, and Ti) by molecular dynamics. Both simple pair potentials, such as Lennard-Jones and Morse, and many-body potentials, such as bond order potential are applied for the simulation of a graphene/metal system at room temperature. Three different structures are considered: (i) graphene interacting with one metal atom; (ii) graphene interacting with a metal nanoparticle, and (iii) three-dimensional graphene network filled with metal nanoparticles. We first determine the potential energy that any graphene/metal system can reach during exposure at 300 K; then, we analyze the interaction dynamics for all considered systems and all potentials. A considerable difference in the interaction between metal nanoparticles with planar and folded graphene was found. For graphene/Ni, graphene/Cu, and graphene/Ti, the Lennard-Jones and Morse potentials provide accurate energetic and structural properties of the studied structures; they also describe interaction in the graphene/metal system in a similar way, at variance with bond-order potential. For graphene/Al, the Tersoff and Morse potentials describe the interaction better than Lennard-Jones. For the simulation of graphene/Me system, the optimal choice of the potential for different structures is of crucial importance. The presented analysis of the interatomic potentials appears to be promising for realistic and accurate simulations of graphene reinforced metal composites.

Ultra-high strength metal matrix composites (MMCs) with extended ductility manufactured by size-controlled powder and spherical cast tungsten carbide

The main challenge of particle reinforced metal matrix composites (MMCs) is balancing strength and ductility. This research uses type 420 stainless steel and spherical cast tungsten carbide (WC/W2C) with a similar powder size and range as raw powders to manufacture laser powder bed fusion (LPBF) 420 + 5 wt% WC/W2C MMCs. LPBF 420 + 5 wt% WC/W2C MMCs contain austenite, martensite, and W-rich carbides (WC/W2C, FeW3C, M6C, and M7C3) from nanometre to micrometre scale. The well-balanced composition creates a crack-free reaction layer between the reinforced particles and matrix. This reaction layer consists of two distinct layers, depending on the element concentration. The LPBF 420 + 5 wt% WC/W2C MMCs achieved an excellent compressive strength of ∼5.5 GPa and a considerable fracture strain exceeding 50 %. The underlying mechanisms for the improved mechanical properties are discussed, providing further insight to advance the application of MMCs via additive manufacturing.

Machining SiC fibre reinforced metal matrix composites – How do different matrix materials affect the cutting performance?

SiC fibre reinforced metal matrix composites find widespread application but show major machining difficulties due to significant variations in constituents' properties. In this sense, while the SiC fibre plays significant strengthening effects, the properties mismatch between the brittle fibre and ductile matrix materials becomes important in their machining performance. Through machining tests, SiC fibre reinforced MMCs with Al (soft) and Ti (hard) matrix alloys are evaluated, showing the variation of interaction between inserts and fibres in cutting due to the different matrix properties. This leads to less tool wear but compromised surface integrity in Al-based composite than in Ti-based one.

Deposition mechanism of ceramic reinforced metal matrix composites via cold spraying

Understanding the mechanism underlying metal matrix composites (MMCs) in cold spraying is critical to fabricate innovative MMC coatings and deposits with tailored microstructures and excellent mechanical performance. In this work, we propose a systematic numerical simulation framework combined with experimental observations to reveal the co-deposition mechanism of cold-sprayed metal/ceramic MMCs. The finite element modeling results and experimental validation found some critical conclusions regarding the deposition mechanism. The modeling results show that most of alumina particles are significantly fractured in Inconel718/alumina coating in contrast to aluminum/alumina coating. This fact suggests that the critical fragmentation velocity (CFV) of ceramic particles is dependent on the hardness of the metal substrate/matrix. Ceramic particles are more prone to fracture when co-deposited with metals having high hardness. Moreover, the simulation results also indicate that the rebounded alumina particles or fragments are possibly captured by incoming metal particles and trapped into MMCs. Since intact alumina particles are barely seen in composites, especially when co-deposited with hard metals, it can be concluded that direct ceramic particle deposition significantly relies on fragmentation. In addition, secondary fragmentation plays a key role in the metal-ceramic co-deposition process. The particles that have completed the impact process may be subjected to secondary fragmentation in the form of new cracks and fragmentation due to the impact by following metal and ceramic particles.

Regulating the microstructure of Ti@TiAlSi core-shell structured reinforcing particles endows Al–Si alloy matrix composites with high strength and ductility

Forming spherical core-shell (CS) structured reinforcing particles, consisting of a Ti core and a surrounding TiAlSi intermetallic shell, by in situ reaction between Ti and Al matrix is a promising approach to overcome the strength-ductility trade-off in particle reinforced Al–Si matrix composites. However, the phase constituent and microstructure of the shells are highly sensitive to the Al–Si alloy composition and processing parameters of the powder thixoforming method. Therefore, the effects of Si content and partial remelting temperature on the microstructure of CS particles and the tensile properties of the resultant composites were investigated in this study. The results indicate that uniform and compact shell can be achieved only by the τ2-phase reaction layer generated during partial remelting. To form the τ2 phase, the Si content in the liquid phase of the semisolid billet prior to thixoforming must be higher than 10.3 wt%. This can be achieved through adjusting the Si content in the Al–Si alloy matrix or/and partial remelting temperature. Moreover, the Ti core radius to shell thickness ratio of ∼1.5 was proposed to achieve the composites with both high strength and ductility. These findings are helpful for designing the microstructure and fabricating CS particles reinforced metal matrix composites with excellent comprehensive mechanical properties.

Selective laser melting and mechanical behavior of Mo-coated diamond particle reinforced metal matrix composites

Defects, such as pores, microcracks, and thermal damage, pose significant challenges in the selective laser melting (SLM) process of diamond reinforced metal matrix composites. To address these issues, this study utilizes Mo-coated diamond particles prepared via salt bath plating for SLM processing of CoCr-diamond composites. The SLM process parameters including laser power, scanning speed, and hatch spacing were systematically optimized using the response surface method (RSM). Subsequently, the microstructure and mechanical properties of the SLMed CoCr-diamond composites were thoroughly investigated. Notably, a protective layer of Mo2C is formed on the surface of diamond particles during the salt bath plating process. When compared to the SLMed CoCr-15 vol% Mo-uncoated diamond composite, the Mo coating significantly enhances the compressive strength by 69 % and flexural strength by an impressive 345 % for the CoCr-15 vol% Mo-coated diamond composite.

Effect of Graphene Particle Diameter on Mechanical Properties of Graphene Composite Material

In order to improve the mechanical properties of alloys and broaden their application fields, high-performance metal matric composites have received more and more attention. Graphene has excellent mechanical properties and is often used as a reinforcing phase for various composite materials. However, as the reinforcing phase of the composite, the number, shape, and size of graphene have a significant effect on the overall mechanical properties of the composites. Therefore, the influence of graphene particle diameter on the mechanical properties of graphene particle reinforced metal matrix composites was studied in this paper. By establishing a series of finite element models, we simulated the mechanical behaviour of composite materials under static tension loading. The relationship between graphene particle diameter and material mechanical properties is revealed.

Physio-mechanical and tribological characterisation of sintered aluminium 7068 modified with NiTiFeAlCu high-entropy-alloy for engineering applications

ABSTRACT Metal particles are gaining attention as reinforcement in metal matrix composites owing to their ductility as compared with ceramic particles, which are inherently brittle. High-entropy-alloy (HEA) particles belong to this category based on their high strength, ductility, and thermal stability. Aluminium-7068 is a new aerospace alloy in the 7000 series that possesses higher strength than aluminium-7075, yet very few studies have considered reinforcement with high-entropy alloy particles. For strength improvement, NiTiFeAlCu (HEA) powder was introduced into the aluminium-7068 matrix at 0, 4, 8, and 12 wt. % at 500 °C via vacuum sintering. The microstructure depicted dispersed particles in the matrix with a linear reduction in porosity as the HEA dosage increased. Consequently, there was a linear increase in density and relative density. 4–12 wt.% HEA engendered linear improvements in yield and ultimate tensile strength, elastic modulus, and hardness; meanwhile, elongation was a progressive decline. The outcome of this study shows that HEA particles in AA-7068 resulted in an improvement of the tensile and hardness properties. The particle addition was observed to reduce the composite’s friction coefficient and wear rate. This report revealed that the performance of AA-7068 can be improved up to 12 wt. % NiTiFeAlCu HEA addition.

A novel prediction method for nanoplatelets content dependent yield strength of graphene nanoplatelets reinforced metal matrix composites at different temperatures

Especially, the quantitative relationship between the thickness and volume fraction of graphene and the grain size of graphene nanoplatelets reinforced metal matrix composites was revealed, based on which the influence of grain refinement, load transfer and dislocation strengthening on the yield strength of composites and their evolution with temperature was quantitatively characterized. Furthermore, by introducing the weakening effect of graphene agglomeration on associated control mechanism of yield strength, a prediction model of temperature dependent yield strength of graphene nanoplatelets reinforced metal matrix composites was established. The proposed prediction approach is verified by comparing the predictions with the experimental data in other literature. Moreover, using the established model, the quantitative effects of length and thickness of nanoplatelets on the yield strength of composites and their evolution with temperature were carried out. This research also provides an effective method for investigating the optimal volume fraction and failure volume fraction of added graphene.

Optimization of wire spark erosion machining of Grade 9 titanium alloy (Grade 9) using a hybrid learning algorithm

Manufacturing has grown challenging because of the increased usage of harder materials, such as titanium alloys, in many industries, such as aerospace, automobiles, and marine. Conventional material removal procedures are not suitable for these tough materials due to their increased hardness and slow machinability. Wire Electrical discharge machining (WEDM) is a modern approach for material removal, particularly for harder materials, such as titanium alloys, nickel alloys, hard particle reinforced metal matrix composites, etc. The research design was performed by deeming the independent factors, such as duration of pulse and applied current. The removal rate of material, surface roughness of the machined region, dimensional deviation, and tolerance errors in form/orientation are considered performance metrics. Taguchi’s approach was engaged to assess the process variables, and the importance of the process factors was established using analysis of variance approach. The purpose of this research is to create an AI based decision making tool, which can be utilized to anticipate the various parameters that impact the WEDM material removal process. The discoveries of the present exploration allowing the manufacturers to make better-informed decisions with a developed model’s capability by demonstrating that the model’s predicted values were in close confirmation to the actual values.

Influence of surface integrity on the fatigue performance of TiB2/Al composite treated by ultrasonic deep rolling: Experiments and simulations

The influences of surface integrity on the fatigue performance of in-situ 6 wt% TiB2/2024Al composite treated by ultrasonic deep rolling (UDR) were comprehensively investigated with both experiments and simulations. Results reveal that only a single pass of UDR treatment can impressively reduce the surface roughness of the fine-turned specimens by 94 %. Moreover, axial compressive residual stress (RSc) larger than −400 MPa and strain hardening (SH) higher than 50 % were obtained on the surface. The comprehensive effect of these surface integrity improvements has enhanced the fatigue limit by 22 %, extended the fatigue life by 10∼20 times, and expanded the safe region in the Goodman-Haigh graph by 14.6 %. More importantly, UDR significantly dispersed the TiB2-particle aggregates in the composite surface, which provided the possibility of improving the surface comprehensive mechanical properties of particles reinforced metal matrix composites (PRMMCs) through a simple and convenient mechanical way.

The effect of coarse and fine Ti3SiC2 particle reinforcement in aluminum matrix composites

Metal matrix composites (MMCs) reinforced by MAX phases are a promising class of advanced materials that exhibit high mechanical strength, wear resistance, and fracture toughness. Compared to MMCs reinforced with conventional ceramic particles, MAX phases do not hinder machinability or electrical and thermal conductivity of the metal matrix. This study investigated the effect of adding 3, 9 and 18 wt% coarse- and fine-sized Ti3SiC2 particles to pure Al. The Ti3SiC2/Al composites were fabricated by spark plasma sintering at a relatively low temperature of 540 °C, preventing the decomposition of the MAX phase and retaining its unique layered structure. It was found that the fine MAX particles hindered the sintering process. A high fraction of fine particles resulted in abundant porosity, weak interfaces and deteriorated mechanical properties. The microstructural analysis revealed a homogenous microstructure with the residual porosity being located mostly at grain boundaries near Ti3SiC2–Al interfaces. In addition, thin oxide layers could be observed at some of the Ti3SiC2–Al interfaces, which can aid in facilitating bonding between Al and Ti3SiC2. The composites with mostly coarse particles exhibited superior mechanical properties. The hardness increased with the addition of MAX particles and was shown to be slightly anisotropic, and the highest bending strength was achieved for the 3 wt% Ti3SiC2/Al. Nanoindentation hardness mapping analysis shed some light on the strengthening mechanism. The results of this study can serve as a basis for further research utilizing MAX-phase particle reinforcements in MMCs.

A comparison study of the strengthening effect of carbon nanomaterial reinforcements in the 3D skeleton-reinforced copper matrix composites

The interfacial bonding and efficient load transfer are the research focus of the carbon nanomaterials (CNMs) reinforced metal matrix composites. In this study, special structured copper composites with CNMs distributing in the 3-D skeleton (CNMs/Cuf®Cu) were designed and prepared. The open cell copper foams reinforced by carbon nanotubes (CNTs), reduced graphene oxide (RGO) or CNTs-RGO hybrid were prepared by electrodeposition with enhanced mechanical strength and acted as the reinforcing skeletons, and the pure copper phase with good ductility and conductivity was continuously filled in the foam pores through powder metallurgy. The 3-D skeleton reinforcing structure, network structured CNTs-RGO hybrid, grain refinement effect and the disordered interface with Cu2O interface products synergistically cause higher load transfer efficiency and result in improved mechanical properties for the CNTs-RGO/Cuf®Cu composite, which shows the ultimate tensile strength (UTS) of 382 MPa, fracture elongation of 43 % and electrical conductivity of 93.26%IACS.

Crystal plasticity finite element modelling and mechanical deformation mechanism of nanolaminated graphene reinforced metal matrix composites

Metal matrix composites with certain hierarchical structures are potential to break out the conflicts between strength and toughness. Nano-carbon like graphene (Gn) reinforced metal matrix composites with nanolaminated structures have been largely developed to overcome this issue. However, the plastic deformation mechanism hiding behind the nanolaminated structures is still lacking. In this study, crystal plasticity finite element simulations and composite structure modeling are combined in order to uncover the mechanical deformation behavior of nanolaminated Gn/Al composites. Different lateral Gn sizes of 180, 360 and 720 nm are considered, while the hybrid lateral Gn sizes of 180 and 720 nm are applied as well. Good consistency between experimental and numerical results indicates the reliability of performed simulations. It is found that the strengthening and hardening behaviors of Gn/Al composites are dominated by Gn rather than Al matrix. The edges of Gn serving as a major dislocation nucleation source produce localization of plastic deformation, while the interiors of Gn activate more slip systems but reduce total shear strains. The edges and interiors of Gn determine the stability of plastic deformation of Gn/Al composites; large edge vs. interior area of Gn will lead to early necking. The rule of mixture fails in predicting the peak tensile strength and tensile strain of Gn/Al composites with hybrid lateral Gn sizes, because the microscopic plastic deformation can largely localize around 180 nm Gn in these hybrid Gn/Al composites. This work is enlightening to design and develop novel smart metal matrix composites.

Design and Development of Novel AA7075-T6 based Armor Plate through Numerical and Experimental Approach

The materials used for ballistic applications have always taken a special spot in the manufacturing and study of protective amours. Although metals like steel provide adequate ballistic protection, they compromise the mobility of the soldier and since high mobility is a primary requirement for soldiers during combat. Therefore, at present most of the researchers are currently focusing on materials with properties like high impact resistance and high strength to weight ratio. In recent times, Aluminum alloys are recognized as the alternative materials which can provide good impact resistance and have a high strength to weight ratio and having better corrosion resistant properties which ultimately make it a suitable material for several military applications. In this research, one of the toughest aluminum alloys AA7075-T6 is considered for designing an armor plate and studied for its ballistic resistance. Initially, the monolithic AA7075-T6 alloy of 18 mm was tested for its ballistic resistance limit and further it is designed with the ceramic plate of 3 mm and base alloy AA7075-T6 of 15 mm was tested to evaluate. Later the monolithic alloy of 18 mm was surface reinforced up to a thickness of 3 mm with different types of reinforcements and evaluated the bullet residual velocity after penetration of the armor piercing projectile. Numerical simulation was conducted using the prominent non-linear dynamic analysis software i.e., Ansys AUTODYNE version 19.2 and the respective values for the surface reinforced metal matrix composites revealed excellent results for the depth of penetration and residual velocity of the projectile.

Machinability of cupola slag incorporated LM11 matrix composites in turning: Surface roughness and MRR analysis

This study explores the potential of using cupola slag, a byproduct of cast iron production, as reinforcement in Al-4.5-Cu (LM11) matrix composites. The composites were fabricated using a low-cost stir casting method, with varying percentages of cupola slag (0 %, 3 %, 5 %, and 7 %) added to the matrix. The cast composites were then evaluated based on their microstructure, microhardness density and machinability indices, including material removal rate, surface roughness, chip thickness and chip analysis during dry turning. A full factorial design of experimentation was employed to determine the effects of different process inputs on machinability, with feed, spindle speed, and weight percentage of cupola slag as the variables. The results showed that 7 wt% cupola slag incorporation improved machinability, but beyond this percentage, the casting became unstable due to reduced wettability. This study offers valuable insights into the machinability of cupola slag embedded cast composites and the influence of different process inputs on their machinability by using a low-cost stir casting method and an unwanted byproduct as reinforcement, this approach offers a novel and sustainable alternative for the reinforcement of metal matrix composites.

Microstructure and mechanical properties of steel wire reinforced Mg matrix composites fabricated by composite extrusion

The Steel/Mg composites were prepared using the composite extrusion method, where AZ31 Mg alloy was used as the matrix and Zn-coated steel wire as the reinforcement. The microstructure evolution and mechanical properties of these composites were systematically studied. The results show that there is an interdiffusion phenomenon of Mg and Zn elements at the interface of the prepared Steel/Mg composites, and an interdiffusion layer with a width of about 15 μm is formed and MgZn and Mg7Zn3 compounds are produced. The inclusion of steel wire in the Mg alloy matrix can significantly reduce its texture strength. Steel/Mg composites have higher tensile and compressive strength than Mg–R. This study provides a novel, time-saving and low-cost method for the manufacture of continuous fiber reinforced metal matrix composites(CFRMMCs), and expands the application of metal composites.

Interfacial reaction and interfacial strengthening mechanism of graphene nanosheets reinforced powder metallurgy nickel-based superalloy composite

Graphene nanosheet (GNS) reinforced nickel based superalloy (FGH96) composites with various interfacial reaction degrees were fabricated by powder metallurgy of Hot Isostatic Pressing (HIP) at sintering temperature range of 1120–1190 °C. The interfacial reaction products [Ti, Nb]C particles were formed in FGH96 metal matrix composite by the in-situ reaction between homogeneously-dispersed GNS and FGH96 matrix. In addition, the interfacial reaction products determined by Transmission Electron Microscopy, the interfacial structure was also determined and named clean interface, transition zone and in-situ generation of metal carbides interface. The interfacial [Ti, Nb]C particles on partially reacted with GNS, led to significant improvement of interfacial strength and consequent reinforced the mechanical transfer efficiency in FGH96 metal matrix consequently, compared to those FGH96 without GNS. The role of interfacial [Ti, Nb]C particles played in determining the interfacial bonding strength and interfacial bonding mode of GNS was discussed. This work emphasizes the importance of the interface state of GNS on the interface structure in metal matrix composites, and may provide new insights into the interfacial phenomena and load transfer mechanism in GNS reinforced metal matrix composites.

Microstructure-based simulation on the mechanical behavior of particle reinforced metal matrix composites with varying particle characteristics

The mechanical performance of metal matrix composites strengthened with particles is predominantly contingent upon the attributes of the incorporated particles. Attaining the optimal particle size, morphology, and interfacial bonding within the composites is paramount for improving the comprehensive properties. In this study, an experimentally congruent model was devised to validate the feasibility of the model predicated on the actual microstructure of the composite. The modeling procedure encapsulated matrix and particle failure, as well as surface-based cohesive damage at the interface, to precisely portray the mechanism of action for the particle characteristics. Additionally, the mechanical behavior and failure evolution mechanism of the composites were simulated by manipulating the pertinent particle factors, including size distribution, interfacial strength, and morphology. The findings demonstrated that an appropriate size distribution between particles and more rounded particles can mitigate stress and strain concentration within the matrix interstitial to particles, resulting in a considerable enhancement in the mechanical performance of the composites. As the interfacial strength decreases, the initial failure progression of the composite shifts from initial cracking within the matrix induced by stress-strain concentration to interfacial failure caused by interfacial debonding, ultimately accelerating the failure of composite. This research will bolster the comprehension of the correlations between microstructural features and mechanical performance in metal matrix composites strengthened with particles, providing an innovative simulation-assisted experimental approach for the rapid development and preparation of novel metal matrix composites.