An overview of additively manufactured metal matrix composites:preparation,performance,and challenge

Metal matrix composites(MMCs)are frequently employed in various advanced industries due to their high modulus and strength,favorable wear and corrosion resistance,and other good properties at elevated temperatures.In recent decades,additive manufacturing(AM)technology has garnered attention as a potential way for fabricating MMCs.This article provides a comprehensive review of recent endeavors and progress in AM of MMCs,encompassing available AM technologies,types of reinforcements,feedstock preparation,synthesis principles during the AM process,typical AM-produced MMCs,strengthening mechanisms,challenges,and future interests.Compared to conventionally manufactured MMCs,AM-produced MMCs exhibit more uniformly distributed reinforcements and refined microstructure,resulting in comparable or even better mechanical properties.In addition,AM technology can produce bulk MMCs with significantly low porosity and fabricate geometrically complex MMC components and MMC lattice structures.As reviewed,many AM-produced MMCs,such as Al matrix composites,Ti matrix composites,nickel matrix composites,Fe matrix composites,etc,have been successfully produced.The types and contents of reinforcements strongly influence the properties of AM-produced MMCs,the choice of AM technology,and the applied processing parameters.In these MMCs,four primary strengthening mechanisms have been identified:Hall–Petch strengthening,dislocation strengthening,load transfer strengthening,and Orowan strengthening.AM technologies offer advantages that enhance the properties of MMCs when compared with traditional fabrication methods.Despite the advantages above,further challenges of AM-produced MMCs are still faced,such as new methods and new technologies for investigating AM-produced MMCs,the intrinsic nature of MMCs coupled with AM technologies,and challenges in the AM processes.Therefore,the article concludes by discussing the challenges and future interests of AM of MMCs.

Research progress in friction stir processing of magnesium alloys and their metal matrix surface composites: Evolution in the 21^(st )century

Rising concerns about climate change drive the demand for lightweight components.Magnesium(Mg)alloys are highly valued for their low weight,making them increasingly important in various industries.Researchers focusing on enhancing the characteristics of Mg alloys and developing their Metal Matrix Composites(MMCs)have gained significant attention worldwide over the past decade,driven by the global shift towards lightweight materials.Friction Stir Processing(FSP)has emerged as a promising technique to enhance the properties of Mg alloys and produce Mg-MMCs.Initially,FSP adapted to refine grain size from the micro to the nano level and accelerated the development of MMCs due to its solid-state nature and the synergistic effects of microstructure refinement and reinforcement,improving strength,hardness,ductility,wear resistance,corrosion resistance,and fatigue strength.However,producing defect-free and sound FSPed Mg and Mg-MMCs requires addressing several variables and their interdependencies,which opens up a broad range of practical applications.Despite existing reviews on individual FSP of Mg,its alloys,and MMCs,an attempt has been made to analyze the latest research on these three aspects collectively to enhance the understanding,application,and effectiveness of FSP for Mg and its derivatives.This review article discusses the literature,classifies the importance of Mg alloys,provides a historical background,and explores developments and potential applications of FSPed Mg alloys.It focuses on novel fabrication methods,reinforcement strategies,machine and tool design parameters,material characterization,and integration with other methods for enhanced properties.The influence of process parameters and the emergence of defects are examined,along with specific applications in mono and hybrid composites and their microstructure evolution.The study identifies promising reinforcement materials and highlights research gaps in FSP for Mg alloys and MMCs production.It concludes with significant recommendations for further exploration,reflecting ongoing advancements in this field.

Recent advances in self-lubricating metal matrix nanocomposites reinforced by carbonous materials:A review

Metal matrix self-lubricating materials lie at the core of cutting-edge aerospace,mechanical,and electrical industries,which demand technological performances that cannot be met by traditional liquid lubricants.Rapid innovation in nanocarbon materials in recent years enabled rapid development of advanced nanocomposites for applications in structural engineering and functional devices.Carbonous materials(e.g.,graphite,graphene and carbon nanotubes),exhibit a wide range of unique electrical,mechanical,and thermal properties,which are also considered ideal lubricating reinforcements for metal matrix nanocomposites(MMCs)with superior mechanical and tribological properties.In this review,we first showcase the distinctive features of the constituents commonly employed in self-lubricating MMCs,encompassing the high-strength metallic matrix and nano-carbonous reinforcement.Then,we present a comprehensive overview of the recent advancements in preparation techniques for these advanced MMCs,followed by an in-depth discussion on their corresponding tribological properties and wear mechanisms.We close this review by outlining key problems to be solved and the future trend of the development in self-lubricating MMCs.

Hot deformation behaviors of 35% SiC_p/2024Al metal matrix composites

The hot deformation behaviors of 35%SiCp/2024 aluminum alloy composites were studied by hot compression tests using Gleeble-1500D thermo-mechanical simulator at temperatures ranging from 350 to 500 °C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 225.4 kJ/mol. To demonstrate the potential workability, the stable zones and the instability zones in the processing map were identified and verified through micrographs. Considering processing map and microstructure, the hot deformation should be carried out at the temperature of 500 °C and the strain rate of 0.1-1 s-1.

Development of Al-12Si-xTi system active ternary filler metals for Al metal matrix composites

To improve the wettability of Al metal matrix composites（Al-MMCs） by common filler metals,Al-12Si-xTi（x=0.1,0.5,1,3.0;mass fraction,%） system active ternary filler metals were prepared.It was demonstrated that although the added Ti existed within Ti（Al1-xSix）3（0≤x≤0.15） phase,the shear strength and shear fracture surface of the developed Al-12Si-xTi brazes were quite similar to those of traditional Al-12Si braze due to the presence of similar microstructure of Al-Si eutectic microstructure with large volume fraction.So,small Ti addition（～1%） did not make the active brazes brittle and hard compared with the conventional Al-12Si braze.The measured melting range of each Al-12Si-xTi foil was very similar,i.e.,580-590 ℃,because the composition was close to that of eutectic.For wettability improvement,with increasing Ti content,the interfacial gap between the Al2O3 reinforcement and filler metal（R/M） could be eliminated,and the amount of the remainder of the active fillers on the composite substrate decreased after sessile drop test at 610 ℃ for 30 min.So,the wettability improvement became easy to observe repeatedly with increasing Ti content.Additionally,the amount and size of Ti（AlSi）3 phase were sensitive to the Ti content（before brazing） and Si content（after brazing）.

MACHINING OF METAL MATRIX COMPOSITES

Two types of aluminium-based composites reinforced respectively with 20 vol short fibre alumina and with a hybrid of 15 vol SiC particle and 5 vol short alumina fibre are machined with different tool materials:cemented carbide,ceramic,cubic boron nitride(CBN)and polycrystalline diamond(PCD).The analysis on tool wear shows that the various tool materials exhibite different tool wear behaviours,and the tool wear mechanisma are discussed.Apparently,PCD tools do not necessarily guarantee dimensional stability but they can provide the most economic means for machining all sorts of composites.Consequently,a suitable tool material is suggested for machining each metal matrix composite(MMC) from the standpoints of tool wear and machined surface finish.

Wear Studies on Metal Matrix Composites: a Taguchi Approach

An attempt has been made to study the influence of wear parameters like applied load, sliding speed, sliding distance and percentage of reinforcement on the dry sliding wear of the metal matrix composites. A plan of experiments, based on techniques of Taguchi, was performed to acquire data in controlled way. An orthogonal array and the analysis of variance were employed to investigate the influence of process parameters on the wear of composites. The objective is to establish a correlation between dry sliding wear of composites and wear parameters. These correlations were obtained by multiple regressions. Finally, confirmation tests were conducted to verify the experimental results foreseen from the mentioned correlations.

Laser Additive Manufacturing on Metal Matrix Composites: A Review

Important progresses in the study of laser additive manufacturing on metal matrix composites(MMCs)have been made.Recent efforts and advances in additive manufacturing on 5 types of MMCs are presented and reviewed.The main focus is on the material design,the combination of reinforcement and the metal matrix,the synthesis principle during the manufacturing process,and the resulted microstructures as well as properties.Thereafter,the trend of development in future is forecasted,including:Formation mechanism and reinforcement principle of strengthening phase;Material and process design to actively achieve expected performance;Innovative structure design based on the special properties of laser AM MMCs;Simulation,monitoring and optimization in the process of laser AM MMCs.

Microstructure evolution of rare earth Pr modified alumina-silicate short fiber-reinforced Al-Si metal matrix composites

Al-Si metal matrix composites (MMCs) reinforced with 20 vol.% alumina-silicate shot fibers (Al2O3-SiO2(sf)) were fabricated by an infiltration squeeze method. Pure Pr metal was added into these composites. The effect of Pr addition on the microstructure evolution of Al-Si MMCs was investigated by SEM,TEM,and EDS. Pr addition is favorable to make uniform microstructures with the modified eutectic Si crystal. PrAlSi phase with high contents of Pr and Si is observed on the interface between the fiber and the m...

Effect of particle characteristics on deformation of particle reinforced metal matrix composites

The particle characteristics of 15%SiC particles reinforced metal matrix composites(MMC)made by powder metallurgy route were studied by using a statistical method.In the analysis,the approach for estimation of the characteristics of particles was presented.The study was carried out by using the mathematic software MATLAB to calculate the area and perimeter of each particle, in which the image processing technique was employed.Based on the calculations,the sizes and shape factors of each particle were investigated respectively.Additionally,the finite element model(FEM)was established on the basis of the actual microstructure.The contour plots of von Mises effective stress and strain in matrix and particles were presented in calculations for considering the influence of microstructure on the deformation behavior of MMC.Moreover,the contour maps of the maximum stress of particles and the maximum plastic strain of matrix in the vicinity of particles were introduced respectively.

Advances in graphene reinforced metal matrix nanocomposites:Mechanisms,processing,modelling,properties and applications

Graphene has been extensively explored to enhance functional and mechanical properties of metalmatrix nanocomposites for wide-range applications due to their superior mechanical,electrical and thermal properties.This article discusses recent advances of key mechanisms,synthesis,manufacture,modelling and applications of graphene metal matrix nanocomposites.The main strengthening mechanisms include load transfer,Orowan cycle,thermal mismatch,and refinement strengthening.Synthesis technologies are discussed including some conventional methods(such as liquid metallurgy,powdermetallurgy,thermal spraying and deposition technology)and some advanced processing methods(such as molecular-level mixing and friction stir processing).Analytical modelling(including phenomenological models,semi-empirical models,homogenization models,and self-consistent model)and numerical simulations(including finite elements method,finite difference method,and boundary element method)have been discussed for understanding the interface bonding and performance characteristics between graphene and different metal matrices(Al,Cu,Mg,Ni).Key challenges in applying graphene as a reinforcing component for the metal matrix composites and the potential solutions as well as prospectives of future development and opportunities are highlighted.

Fiber Traction Printing:A 3D Printing Method of Continuous Fiber Reinforced Metal Matrix Composite

A novel metal matrix composite freeform fabrication approach,fiber traction printing(FTP),is demonstrated through controlling the wetting behavior between fibers and the matrix.This process utilizes the fiber bundle to control the cross-sectional shape of the liquid metal,shaping it from circular to rectangular which is more precise.The FTP process could resolve manufacturing difficulties in the complex structure of continuous fiber reinforced metal matrix composites.The printing of the first layer monofilament is discussed in detail,and the effects of the fibrous coating thickness on the mechanical properties and microstructures of the composite are also investigated in this paper.The composite material prepared by the FTP process has a tensile strength of 235.2 MPa,which is close to that of composites fabricated by conventional processes.The complex structures are printed to demonstrate the advantages and innovations of this approach.Moreover,the FTP method is suited to other material systems with good wettability,such as modified carbon fiber,surfactants,and aluminum alloys.

Development of three kinds of active ternary filler metals of AI-Si-Ti, Zn-AI-Ti and Cu-AI-Ti systems for AI metal matrix composites

To improve the wettability of common fiUer metals on Al metal matrix composites （ AI-MMCs ） , three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-Al-Ti systems, were prepared by the addition of Ti. Excessive melting temperature made the gravity segregation of Ti remarkable in ingot. The effect of Ti content on the melting point for AI-Si-Ti ternary system was not as sensitive as that for Al-Ti binary system. The Al-12Si-1Ti filler metal showed good ability to form brazing foil during rapid cooling, ductile fracture surface and similar shear strength to conventional Al-12Si filler metal. Moreover, the Al2 03 reinforcements on initial surface could be covered by the Al-12Si-1Ti filler metal without interfacial gaps after sessile drop test. For Zn-9.5Al-0. 5 Ti braze alloy, severe vaporization of Zn and severe segregation of Ti Occurred. During wettability test for traditional Al-12Si and Zn-9.5Al-0. 5Ti, although some Si or Zn could penetrate into the composite, interfacial gap still remained. The prepared Cu-19Al-1 Ti interlayer consisted of primary phase of Al4Cu9 and network Cu-Al-Ti ternary intermetaUic compound, showing poor ability to form foil and very brittle nature. These results demonstrated that Al-Si-Ti system should be promising for Al-MMCs.

Thermal residual stresses and stress distributions under tensile and compressive loadings of short fiber reinforced metal matrix composites

The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance. [

Thermal Cyclic Effects of Metal Matrix Composites

Aim To simulate the thermal cyclic effects of metal matrix compeithe. Methods Based on Eshelby′s inclusion theory, a constitutive model for metal matrix composites and an elastic constraint method were formulated to predict the cyclic isothermal and cyclic thermomechanical behaviors of metal matrix composites. Results and Conclusion A SiC reinforced A1 2xxx-T4 composite was studied theoretically with the model. With the constitutive relation of the matrix, the mechanical behaviors of the composite under different loading condition, such as different loading rates, mechanical and thermal mechanical cyclic loading, can be quantitatively predicted. The thermal ratchetting effect of the composite can be predicted by the model.

Corrosion Behavior and Protection Efficiency of 2024Al and SiC_p/2024Al Metal Matrix Composite

The corrosion resistance of 2024 Al and SiC particle reinforced 2024 Al metal matrix composite (SiCp?024AI MMC) in 3.5% NaCl solution was investigated with electrochemical method and immersion test, and the corrosion protection of sulfuric acid anodized coatings on both materials was evaluated by electrochemical impedance spectroscopy. The results showed that the SiCp?024AI MMC is more susceptible to corrosion than its matrix alloy in 3.5% NaCI. For 2024AI, the anodized coating provides excellent corrosion resistance to 3.5% NaCI. The anodized coating on the SiCp?024AI provides satisfactory corrosion protection, but it is not as effective as that for 2024AI because the structure of the anodized layer is affected by the SiC particulates.

Fabrication and abrasive wear properties of metal matrix composites reinforced with three-dimensional network structure

Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-porosity and super-strong skeleton. The aluminum magnesium matrix composites reinforced with three-dimensional network structure were prepared using the infiltration technique by pressure assisting and vacuum driving. Light interfacial reactions have played a profitable role in most of the ceramic-metal systems. The metal matrix composites interpenetrated with the ceramic phase have a higher wear resistance than the metal matrix phase. The volume fraction of ceramic reinforcement has a significant effect on the abrasive wear, and the wear rate can be decreased with the increase of the volume fraction of reinforcement.

Features of microstructure and fracture in the transient liquid phase bonded aluminium-based metal matrix composite joints

Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ～200 MPa and the shear strength of 70 MPa ～100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).

Multi-objective optimization of friction stir welding parameters using desirability approach to join Al/SiC_p metal matrix composites

Silicon carbide particulate （SiCp） reinforced cast aluminium （A1） based metal matrix composites （MMCs） have gained wide acceptance in the fabrication of light weight structures requiring high specific strength, high temperature capability and good wear resistance. Friction stir welding （FSW） process parameters play major role in deciding the performance of welded joints. The ultimate tensile strength, notch tensile strength and weld nugget hardness of friction stir butt welded joints of cast A1/SiCp MMCs （AA6061 with 20% （volume fraction） of SiCp） were investigated. The relationships between the FSW process parameters （rotational speed, welding speed and axial force） and the responses （ultimate tensile strength, notch tensile strength and weld nugget hardness） were established. The optimal welding parameters to maximize the mechanical properties were identified by using desirability approach. From this investigation, it is found that the joints fabricated with the tool rotational speed of 1370 r/min, welding speed of 88.9 mm/min, and axial force of 9.6 kN yield the maximum ultimate tensile strength, notch tensile strength and hardness of 265 MPa, 201 MPa and HV 114, respectively.

PULSED Nd-YAG LASER WELDING OF AN AI-SiC_p METAL MATRIX COMPOSITE

A study is presented of the laser welding behaviour of an SiC particulate re-inforced Al-alloy comPOsite using a pulsed Nd-YAG laser. The influences of laser weldingparameters of laser intensity, pulse duration and the beamjs focus position on the depth ofweld penetration as well as the size of weld bead width were investigated. A typical mi-crostructure of a weld section reveals that the three distinct zones are present. Cracks andporosity were fOund to be two major defects in laser welded metal matrix composites(MMC). These investigations have led to an optimum welding condition proposed forlaser welding of SiC partiulate reinforced aluminium alloy comPosites with minimum de-fects.