Processing of nanostructured metallic matrix composites by a modified accumulative roll bonding method with structural and mechanical considerations

Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. A1/B4C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B4C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes.

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.

Effects of infiltration parameters on mechanical and microstructural properties of tungsten wire reinforced Cu_(47)Ti_(33)Zr_(11)Ni_6Sn_2Si_1 metallic glass matrix composites

Cu47Ti33Zr11Ni6Sn2Si1-based bulk metallic glass matrix composites reinforced with tungsten wires were fabricated by infiltration process at different temperatures （850, 900, 950 and 1000 °C） and time （10, 20 and 30 min） in a quartz or a steel tube. The mechanical tests were carried out by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the maximum strength and total strain of the composite are 1778 MPa and 2.8% fabricated in steel tube at 900 °C for 10 min, and 1582 MPa and 3.6% fabricated in quartz tube at 850 °C for 10 min, respectively.

Statistical Analyses of the Strengths of Particulate Reinforced Metal Matrix Composites(PRMMCs)Subjected to Multiple Tensile and Shear Stresses

For design and application of particulate reinforced metal matrix composites(PRMMCs),it is essential to predict the material strengths and understand how do they relate to constituents and microstructural features.To this end,a computational approach consists of the direct methods,homogenization,and statistical analyses is introduced in our previous studies.Since failure of PRMMC materials are often caused by time-varied combinations of tensile and shear stresses,the established approach is extended in the present work to take into account of these situations.In this paper,ultimate strengths and endurance limits of an exemplary PRMMC material,WC-Co,are predicted under three independently varied tensile and shear stresses.In order to cover the entire load space with least amount of weight factors,a new method for generating optimally distributed weight factors in an n dimensional space is formulated.Employing weight factors determined by this algorithm,direct method calculations were performed on many statistically equivalent representative volume elements(SERVE)samples.Through analyzing statistical characteristics associated with results the study suggests a simplified approach to estimate the material strength under superposed stresses without solving the difficult high dimensional shakedown problem.

Probabilistic Modelling of Microstructural Evolution in Zr Based Bulk Metallic Glass Matrix Composites during Solidification in Additive Manufacturing

Bulk metallic glass and their composites (BMGMCs) are a new class of materials which possess superior mechanical properties as compared to existing conventional materials. Owing to this, they are potential candidates for tomorrow’s structural applications. However, they suffer from poor ductility and little or no toughness which render them brittle and they manifest catastrophic failure under applied force. Their behavior is dubious, unpredictable and requires extensive experimentation to arrive at conclusive results. In present study, an effort has been made to design bulk metallic glass matrix composites by the use of modeling and simulation. A probabilistic cellular automaton (CA) model is developed and described in present study by author which is used in conjunction with earlier developed deterministic model to predict microstructural evolution in Zr based BMGMCs in additive manufacturing liquid melt pool. It is elaborately described with an aim to arrive at quantitative relations which describe process and steps of operations. Results indicate that effect of incorporating all mass transfer and diffusion coefficients under transient conditions and precise determination of probability number play a vital role in refining the model and bringing it closer to a level that it could be compared to actual values. It is shown that proposed tailoring can account for microstructural evolution in metallic glasses.

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.

Fabrication,microstructures,and properties of copper matrix composites reinforced by molybdenum-coated carbon nanotubes

Multiwalled carbon nanotubes （CNTs） were coated by a molybdenum layer using carbonyl thermal decomposition process with a precursor of molybdenum hexacarbonyl. The Mo-coated CNTs （Mo-CNTs） were added into copper powders to fabricate Mo-CNT/Cu composites by means of mechanical milling followed by spark plasma sintering. The Mo-CNTs were uniform dispersion in the Cu matrix when their contents were 2.5 vo1.%-7.5 vol.%, while some Mo-CNT clusters were clearly observed at additions of 10.0 vo1.%-15.0 vol.% Mo-CNTs in the mixture. The mechanical, electrical, and thermal properties of the Mo-CNT/Cu composites were characterized, and the results showed that the tensile strength and hardness were 2.0 and 2.2 times higher than those of CNT-free specimens, respectively. Moreover, the Mo-CNT/Cu composites exhibited an enhanced thermal conductivity but inferior electrical conductivity compared with sintered pure Cu. The uncoated CNT/Cu composites were fabricated by the similar processes, and the measured tensile strength, hardness, thermal conductivity, and electrical conductivity of the CNT/Cu composites were lower than those of the Mo-CNT/Cu composites.

Fabrication and thermal conductivity of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.

Microstructure and thermal properties of copper matrix composites reinforced with titanium-coated graphite fibers

Milled form of mesophase pitch-based graphite fibers were coated with a titanium layer using chemical vapor deposition technique and Ti-coated graphite fiber/Cu composites were fabricated by hot-pressing sintering. The composites were characterized with X-ray diffraction, scanning/transmission electron microscopies, and by mea- suring thermal properties, including thermal conductivity and coefficient of thermal expansion （CTE）. The results show that the milled fibers are preferentially oriented in a plane perpendicular to the pressing direction, leading to anisotropic thermal properties of the composites. The Ti coating reacted with graphite fiber and formed a continuous and uniform TiC layer. This carbide layer establishes a good metallurgical interracial bonding in the composites, which can improve the thermal properties effectively. When the fiber content ranges from 35 vol% to 50 vol%, the in-plane thermal conductivities of the composites increase from 383 to 407 W.（m.K）-~, and the in-plane CTEs decrease from 9.5 x 10-6 to 6.3 10-6 K-1.

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.

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...

Strengthening mechanisms based on reinforcement distribution uniformity for particle reinforced aluminum matrix composites

A modified mixed strengthening model was proposed for describing the yield strength of particle reinforced aluminum matrix composites.The strengthening mechanisms of the composites were analyzed based on the microstructures and compression mechanical properties.The distribution uniformity of reinforcements and cooperation relationship among dislocation mechanisms were considered in the modified mixed strengthening model by introducing a distribution uniformity factor u and a cooperation coefficient fc,respectively.The results show that the modified mixed strengthening model can accurately describe the yield strengths of Al3Ti/2024Al composites with a relative deviation less than1.2%,which is much more accurate than other strengthening models.The modified mixed model can also be used to predict the yield strength of Al3Ti/2024Al composites with different fractions of reinforcements.

Ballistic performance of tungsten particle/metallic glass matrix composite long rod

In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.

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.

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.

Improved wettability and mechanical properties of metal coated carbon fiber-reinforced aluminum matrix composites by squeeze melt infiltration technique

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix,nickel-and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique.The interface wettability,microstructure and mechanical properties of the composites were compared and investigated.Compared with the uncoated fiber-reinforced aluminum matrix composite,the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process.Under the same processing condition,aluminum melt was easy to infiltrate into the copper-coated fiber bundles.Furthermore,the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber−matrix interface bonding performance.The mechanical properties were evaluated by uniaxial tensile test.The yield strength,ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa,140 MPa and 82 GPa,respectively.In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite,the yield strength,ultimate tensile strength and elastic modulus were about 60 MPa,70 MPa and 79 GPa,respectively.The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber−matrix interface bonding,which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state,giving full play to the bearing role of carbon fiber.

Effects of reinforcement on wear resistance of aluminum matrix composites

The effect of reinforcement on the wear mechanism of metal matrix composites （MMCs） was investigated by considering different parameters, such as sliding distance （6 km）, pressure （0.14-1.1 MPa） and sliding speed （230-1480 r/min）. The wear mechanisms of an MMC and the corresponding matrix material under similar experimental conditions were compared on a pin-on-disc wear machine. The pins were made of 6061 aluminum matrix alloy and 6061 aluminum matrix composite reinforced with 10% Al2O3 （volume fraciton） particles （6-18μm）. The disc was made of steel. The major findings are as follows： the MMC shows much higher wear resistance than the corresponding matrix material; unlike that of matrix material, the wear of MMC is very much linear and possible to predict easily; the wear mechanism is similar for both materials other than the three-body abrasion in the case of MMC; the reinforced particles resist the abrasion and restrict the deformation of MMCs which causes high resistance to wear. These results reveal the roles of the reinforcement particles on the wear resistance of MMCs and provide a useful guide for a better control of their wear.