Metal Matrix Composite Structures Research Articles

Optimized analytical approach for the detection of process-induced defects using acoustic emission during directed energy deposition process

Directed energy deposition (DED), an advanced additive manufacturing (AM) technique, facilitates the production of complex metallic and metal matrix composite structures. The DED process has continuously improved and offers numerous advantages for depositing high-quality coatings with excellent wear and corrosion resistance onto metallic surfaces. The dynamic nature of the process, however, introduces a significant risk of process-induced defects in manufactured parts. This study presents an optimized analytical approach using acoustic emission (AE) based defect detection technique to identify and quantify process-induced cracks during the DED process. The developed signal processing technique enabled the identification of actual AE events associated with cracking, distinguishing them from other disturbances. Experimental validation was conducted using manufactured parts that were longitudinally sectioned to determine the relationship of the crack location with the recorded acoustic signal. The demonstrated correlation of acoustic signatures with cracking illustrates the robustness of the AE technique to identify the process-induced cracking for quality assurance during the DED process.

RETRACTED: Tribological and microstructure studies of LM26/SiC metal matrix composite materials and structures for high temperature applications

This study aimed to investigate the tribological and microstructural characteristics of LM26 composites reinforced with silicon carbide to evaluate their suitability for high-temperature applications. For the sample fabrication, the modified stir-casting method was optimized using a Taguchi L16 orthogonal array. The wear rate and friction behavior were evaluated using the Taguchi’s S/N ratio analysis. When SiC was incorporated into the composite, the wear resistance increased by up to 15 wt%. The wear resistance of the LM26/SiC composite was improved compared to that of the pure LM26 aluminum alloy. The results of this study provide useful information to improve the wettability of metal matrix composites made from commercial-grade LM26 aluminum alloy by adjusting the SiC weight percentage. This type of composite has the potential as a replacement material for traditional applications such as heat sinks, heat exchanger fins, and electronic packaging.

Effect of Gas Atmosphere in Aluminobarothermal Synthesis on the Structure of Metal Matrix Composites Based on Fe – Cr – Mn – Mo Alloy

Effect of Gas Atmosphere in Aluminobarothermal Synthesis on the Structure of Metal Matrix Composites Based on Fe – Cr – Mn – Mo Alloy

Shakedown-reliability based fatigue strength prediction of parts fabricated by directed energy deposition considering the microstructural inhomogeneities

For mechanical components made by additive manufacturing (AM) techniques such as directed energy deposition (DED), micropores and other defects prevalently exist in the microstructure and they significantly reduce the reliability of these parts. To allow the influence of these microstructural features over the load bearing capacity to be considered in the design stage of AM structures, in the present paper we developed a multiscale numerical approach. The goal of this approach is to predict the failure probability of AM structures subjected to time-varied loadings, and it is realized through combining statistical homogenization, shakedown analyses, and reliability methods such as first-order reliability method and Monte Carlo simulation. Based on this strategy, we employed statistics of material parameters obtained from micromechanical models as inputs, implemented numerical tools and applied them to two exemplary structures, the plate with a hole and an aircraft bracket. Through a series of case studies carried out using different methods and under different assumptions of material randomness, the paper confirmed the robustness of the derived results and explained the mechanism of how micropores influence the structural reliability. The method developed in this paper can be a viable means for the design and optimization of metallic and metal matrix composite structures produced by AM techniques.

Exploring the Potential of Wire Fed Direct Energy Deposition of Aluminum–Boron Nitride Nanotube Composite: Microstructural Evolution and Mechanical Properties

Recent advancements have shown great promise in utilizing wire‐fed direct energy deposition (DED) for building aluminum alloy structures. However, utilizing the wire‐fed DED approach for fabricating metal matrix composite structures remains a significant challenge. Herein, a wire‐based additive manufacturing process is used to successfully produce a 1D boron nitride nanotube (BNNT)‐reinforced aluminum composite with high strength. Al‐BNNT electrode is developed in house. The microstructural changes that occur during layer‐by‐layer deposition are investigated. The grain morphology changes from equiaxed grains in the bottom layer to columnar grains in the top layer. BNNTs act as nuclei to promote the formation of equiaxed grains and interfacial compounds (AlN and AlB2) during solidification. This results in improved strength, with Al‐BNNT composite exhibiting a tensile strength of 47 MPa, 2.3 times higher than its pure Al. Higher strength is attributed to the retention and uniform distribution of BNNT reinforcement in the melt pool, leading to effective load transfer. This study demonstrates the potential of additive manufacturing for producing high‐performance metal matrix composites with novel 1D reinforcements and improved multifunctional properties.

Erosion Behavior of Stellite-6 and WC-12Co Coatings on SA213-T22 Boiler Steel

At Mae-Moh power plant, Thailand, superheater tubes, which are exposed to a fly ash environment, often degrade due to solid particle erosion. To extend the service lifetime of the superheater tubes, the high velocity oxy-fuel (HVOF) thermal spray technique is used to deposit a protective coating on the material, SA213-T22 steel. In this work, the solid particle erosion of Stellite-6 and WC-12Co coatings was investigated using erodent particle impingement at angles of 30 and 90°. This was carried out with an average particle size of 60 μm. The erosion behavior of SA213-T22 with and without Stellite-6 and WC-12Co coatings was examined using ductile and brittle erosion modes. The erosion testing resulted in the brittle mode for both Stellite-6 and WC-12Co coatings, while the SA213-T22 without coating indicated the ductile mode. On investigation of the surface morphology, the SA213-T22 steel showed ploughing and microcutting. The Stellite-6 coating showed some evidence of ductile erosion such as lips on the coating surface, different from the WC-12Co coating which showed microcracks and deep cavities. The erosion resistance of the Stellite-6 coating was higher than the WC-12Co coating. This was due to the strength and toughness of the metal matrix composite structure and the low porosity of the coating.

Parametric Scaffold Design for Property Control of Multi-Material Structure in Metallic Hybrid Additive Manufacturing

Additive manufacturing (AM) technologies have lots of advantages to fabricate complex structures in both shape and material composition. However, there is rarely a single-step AM process for high-performance ceramic-reinforced metal matrix composite (MMC) with complex geometric shapes. To achieve the fabrication of MMC structures with controlled mechanical properties, this paper proposes a novel design and manufacturing method for the modular hybrid AM process combining a binder jetting sintering process with conventional casting. At first, different material compositions are assigned to these two processes, and then a parametric design method is applied to control the generation of a qualified (self-supported) scaffold, which will be printed as a ceramic reinforcement frame with less AM post-processing. Finally, the whole sintered scaffold is immersed in molten metal for casting control. In this way, by changing the unit cell type, size, and porosity ratio of the parametric scaffold, the composition ratio of materials changes, which results in the change of the structure's mechanical properties. A case study is presented at the end to prove the proposed concept.

Multiscale topology optimization of biodegradable metal matrix composite structures for additive manufacturing

Recent advances in biomedical engineering have promoted the development of innovative metal implants that have integrated mechanical and biodegradable properties. Most of the existing implant designs were created by using a trial-and-error approach, which depends on the designer's experience. Alternatively, inverse design approaches, such as topology optimization, have evolved into an efficient design solution to optimize the structural and material layout within a given design domain. Here we introduce a novel topology optimization scheme to support the microstructural design of biodegradable metal matrix composite structures (BM−MCS). The effect of material degradation on the mechanical performance of the structure is considered by integrating a degradation simulation algorithm into the structural finite element (FE) analysis. The objective function is to minimize the structural compliance at macroscale in a certain number of time steps to realize sufficient structural integrity in the initial bone healing stage, and the different stiffness reduction properties can be adjusted by changing the volume ratio of the two base constitutive biodegradable materials. The sensitivity of the above objective function concerning design variables was derived with considering the time-dependent degradation of the biodegradable material. Several numerical design examples were presented and benchmarked with classical designs. Finally, several prototypes were fabricated by integrating additive manufacturing with casting technology. Collectively, this demonstrates the feasibility and effectiveness of the proposed inverse design method for additive manufacturing.

Progress in aluminium and magnesium matrix composites obtained by spark plasma, microwave and induction sintering

ABSTRACT Aluminium and magnesium matrix composites are attractive lightweight materials with strength surpassing that of the corresponding matrix metals. Recent years have seen extensive research aimed at finding ways to control the structure of metal matrix composites and obtaining materials with new sets of properties. This review aims to show that field-assisted sintering is a promising approach for the powder metallurgy processing of aluminium and magnesium matrix composites. The review focuses on the achievements in the compositional and microstructural design and properties of aluminium and magnesium matrix composites obtained by spark plasma sintering, microwave sintering and induction sintering. Issues related to the process scale-up in the field-assisted sintering technologies are also addressed.

Physical methods of processing melts of metal matrix composites: Сurrent state and prospects

This review focuses on the known theoretical and experimental results in the field of obtaining metal matrix composite materials by processing the melts using physical methods in the conditions of casting and metallurgical processes. The possibilities, advantages and disadvantages of various physical impact methods are considered from the standpoint of their effect on the structural and morphological characteristics, physicomechanical and operational properties of cast composite materials based on aluminum and its alloys. The paper provides a classification and a detailed description of physical methods used for melt processing when obtaining metal matrix composites depending on the melt state during processing (melting, pouring and crystallization) and according to the physical principle of the effects applied (thermal, electromagnetic, cavitation, mechanical, etc). The paper describes a contemporary view of the laws and mechanisms of the effect exerted by melt processing using physical methods on the structure and phase formation processes of as-cast metal matrix composites. The currently known effects of the impact on their structure are described from a qualitative and quantitative point of view, in particular, effects associated with a change in the wettability of particles, their distribution, dispersion and morphology, as well as with a change in the structural state of the matrix material. The paper systematizes the data on the properties of metal matrix composites obtained using physical impacts on the melt during melting and crystallization. The research shows the prospects for the development and practical application of physical impact methods for melts in the production of metal matrix composites based on various matrix materials and reinforcement systems including endogenously, exogenously and integrally reinforced composite materials. Priority areas of theoretical research and experimental development are discussed highlighting discussion areas and issues in the field of obtaining metal matrix composites using physical impacts on melts during melting and crystallization. Areas for future research in this field are proposed based on the systematic analysis of key problems limiting the widespread industrial use of physical methods for melt processing.

Structure and Properties of Metal-Matrix Composites Based on an Inconel 625–TiB2 System Fabricated by Additive Manufacturing

This research work studies the structural phase parameters and physicomechanical properties of metal-matrix composite materials based on a Ni–TiB2 system obtained by additive manufacturing (specifically, direct laser deposition). The properties of the composites obtained were investigated at high temperatures (up to 1000 °C). The feasibility of the fabrication of a composite nanostructure of alloy with advanced physicomechanical properties was shown. The introduction of reinforcing TiB2 particles into an Inconel 625 matrix was confirmed to increase the microhardness and tensile strength of the material obtained. Apparently, the composite structure of the samples facilitates the realisation of several strengthening mechanisms: (1) a grain boundary mechanism that causes strengthening and dislocation movement; (2) a mechanism based on the grain structure breakdown and Hall–Petch relationship realisation.

The Laser Alloying Process of Ductile Cast Iron Surface with Titanium Powder in Nitrogen Atmosphere

The article presents the results of the laser alloying process of a ductile cast iron EN-GJS 350-22 surface with titanium powder in nitrogen atmosphere. The aim of this research was to test the influence of nitrogen atmosphere on the structure and properties of the ductile cast iron surface layer produced by a laser alloying process with titanium. The laser alloying process was conducted using a Rofin Sinar DL020 2 kW high-power diode laser (HPDDL) with rectangular focus and uniform power density distribution in the focus axis. The tests of the produced surface layers included macrostructure and microstructure observations, X-ray diffraction (XRD) analysis, energy-dispersive spectroscopy (EDS) on scanning electron microscope (SEM) and transmission electron microscope (TEM), Vickers hardness and solid particle erosion according to ASTM G76-04 standard. As a result of the laser alloying process in nitrogen atmosphere with titanium powder, the in situ metal matrix composite structure reinforced by TiCN particles was formed. The laser alloying process of ductile cast iron caused the increased hardness and erosion resistance of the surface.

Ceramic metal composite approach for the advanced Hadfield steel

This work is aiming at attaining the highest wear abrasion resistance of Hadfield steel, through using ceramic metal matrix approach. The metal matrix composite structure was attained through using honey comb method. Then, microstructure observations, wear abrasion resistance of the metal matrix composite structure were well tracked by using optical microscope, SEM, XRD, and wear test. Comparing with the reference Hadfield steel, it was found that wear abrasion resistance has been multiplied through using ceramic metal matrix composite structure, adding to the great enhancement of strain hardening property. These results refer to the possibility of using this new technique for producing the crusher components to be applied under severe mining conditions.

Manufacturing of complex diamond-based composite structures via laser powder-bed fusion

Manufacturing complex metal matrix composite (MMC) structures by laser powder-bed fusion (LPBF) could unleash their full potential but is difficult due to the presence of reinforcement. Unmelted particles negatively affect the pool dynamics, cause critical spatter ejections, and form printing defects. In this work, by taking copper (Cu) / diamond (D) composite as an example for its prospective thermal management applications and machinability limitations; we discovered that adding steps to LPBF enables the fabrication of high-quality materials and structures. We demonstrated that adding a recoating step improves the composite quality compared to structures manufactured by conventional LPBF. Adding a remelting step enabled further improvement by limiting the generation of spatter and printing defects, leading to 3D laser print dense (97%), highly thermally conductive (349 W/m K) and complex Cu/5 vol% D structures. Therefore, pursuing research into nonconventional LPBF could open new avenues for manufacturing MMCs.

The Laser Alloying Process of Ductile Cast Iron Surface with Titanium

The article presents the results of the laser alloying process of ductile cast iron EN-GJS 350-22 surface with titanium. The laser alloying process was conducted on 2 kW high power diode laser (HPDDL) Rofin Sinar DL02 with rectangular focus and uniform power density distribution in the focus axis. The laser alloying was conducted with constant laser beam power and processing speed with titanium powder feed rate variation. The tests of the produced surface layers included macrostructure and microstructure observations, X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis, Vickers hardness, and solid particle erosion according to ASTM G76-04 standard. To assess the erosion mechanism, SEM observations of worn surfaces after erosive test were carried out. As a result of laser alloying of a ductile cast iron surface, the in situ metal-matrix composite structure was formed with TiC reinforcing particles. The microstructure change resulted in the increase of surface layers hardness and erosion resistance in comparison to the base material.

Numerical Study of the Toughness of Complex Metal Matrix Composite Topologies

Fracture toughness tests (compact tension) of a dual material composed of a structured Metal Matrix Composite (MMC) (martensitic steel and titanium carbides, named MS-TiC) surrounded by martensitic steel (MS) are simulated with a Discrete Elements Model (DEM) developed with the GranOO Workbench. The MMC structures are micro-lattices such as gyroid, octet-truss and Face and Body-Centered Cubic with Z-truss (FBCCZ). The volume fraction of these MMC inserts and their cell size are fixed, the influence of the cell orientation is studied. The aim of the study is to determine the configuration of topology (shape and cell orientation) which absorbs the most energy and is the most crack resistant. From experimental tests, the Young’s moduli and the failure stresses of the MMC material and the metal are estimated, and thanks to beam network discretization, a local stiffness and a failure criterion are evaluated to finally obtain a crack propagation path. To verify the suitability of the DEM model, a Compact Tension (CT) experimental test on MMC specimens is performed and a stress intensity factor is computed. A good agreement with an error less than 10% is obtained between experimental and simulated KIc with values respectively equal to 35 and 37 MPam. From DEM simulations based on the CT tests, the FBCCZ cell absorbs the most energy at the crack propagation compared to other structures and the steel. The crack propagation length depends on the shape of the topology. The originality of the study lies in the modeling, with granular properties using DEM, of the mechanical and elastic fracture behavior of these topological structures classically solved by Finite Elements Method (FEM): the microscopic constitutive relations have been validated macroscopically by experimental tests on homogeneous MMC materials.

Fine control over the structure and morphology of metal-matrix composites employing submicron oxide particles with the adjustable redox-activity

It is shown that copolycondensation of mixed vanadic and molybdic acids under the solvothermal conditions yields substitutional solid solution V2O5 : MoO3 (isostructural to V2O5 xerogel) the redox activity of which exhibits increase with the MoO3 content. Thus obtained mixed oxide 0.5V2O5 : 0.5MoO3 with high redox activity, being codeposited with the galvanic nickel, ensure multicenter nucleation of metal phase, yields compact composite with the enhanced corrosion stability.

Comprehensive analysis and manufacture of recycled aluminum based hybrid metal matrix composites through the combined method; sintering and sintering + forging

Recycled AA7075 aluminum alloy and pure electrolytic copper were used as the matrix to manufacture new aluminum-copper metal matrix composites (ACMMCs). Powder metallurgy methods were used and the green compacts were finalized by sintering only and sinter + forging. Experimental and numerical investigation of recycled hybrid metal matrix composites manufactured by the two methods was performed. Al–Cu matrix combined with the reinforcements ZnO, Nb2Al and SiC. Two basic formulations were used where the contents Nb2Al and SiC was kept constant and the content of ZnO were 15 wt% and 30 wt%, respectively. The effects of these reinforcements used in the hybrid metal matrix composite structure on the mechanical and physical properties were investigated. The Nb2Al, SiC ratios used in the structure (chemical interaction in the internal structure, the effects on static-dynamic compression and wear behaviors) were kept constant, in particular the ZnO component (interactions with other components and their effects on electrical properties) were investigated. Micro-hardness analyses, surface scratch tests, quasi-static and dynamic compression tests were conducted. Also, electrical conductivity of the composites were determined. The effect of the composite's formulations and production method on the results were investigated. It was found when ZnO content was reduced the yield stress and ultimate strength values increased, but their resistance to impact loading reduced. Also, sinter + forged samples exhibited higher yield stress and ultimate strength than the just sintered samples. The damage and microstructural analyses were performed by Scanning Electron Microscope (SEM). Moreover, a non-linear numerical model was utilized to simulate quasi-static compression and dynamic compression (low velocity impact) behaviors of the composites for both formulations and manufacturing methods. Finite element simulations were performed using the ABAQUS™/Explicit dynamic finite element software. It was determined that there was a satisfactory agreement between experimental and finite element model results.

Functionally graded metal matrix composite of Haynes 282 and SiC fabricated by laser metal deposition

In the current study, functionally graded metal matrix composite structure of Haynes 282 (HY282) superalloy reinforced with SiC particles with varying composition, structure and property in a single deposit is successfully fabricated using laser metal deposition (LMD). Due to the high laser energy used it was found that SiC disassociated profusely into Si and C with HY282 causing several reaction products that included a Si-rich supersaturated austenitic γ matrix, γ′ Ni3(Al,Ti,Si), M(Ti,Mo)C, M23(Cr,Mo,Si)C6, M6(Mo,Ti)C, M7(Cr, Mo)C3 carbides, and γ/γ′ lamellar eutectics. Due to the rapid cooling nature of the process, the graded structure consists of non-equilibrium microstructure, several deleterious secondary phases, and heavy segregation behavior that lead to unwanted properties. Hence a heat-treatment cycle was performed on the as-deposited sample to ensure homogenization of the microstructures. The influence of composition variation in each layer on the microstructure, chemistry, and microhardness were characterized by scanning electron microscopy, energy dispersive spectroscopy, and micro-indentation techniques. The complex phases found in the graded sample in every layer were estimated by calculation of phase diagrams viewpoint to establish the feasibility of using computational thermodynamic simulations to predict the manifestation of the experimentally observed structure.

Mechanical Alloying and Electrical Current-Assisted Sintering Adopted for In Situ Ti-TiB Metal Matrix Composite Processing.

In this work, mechanical alloying and electrical current-assisted sintering was adopted for in situ metal matrix composite material processing. Applied at the initial powder stage, mechanical alloying enables a homogeneous distribution of the starting elements in the proposed precursor powder blends. The accompanying precursor preparation and the structurally confirmed size reduction allow obtainment of a nanoscale range for the objects to be sintered. The nano precursors aggregated in the micro-sized particle objects, subjected to electrical current-assisted sintering, characterize the metal matrix composite sinters with high uniformity, proper densification, and compaction response, as well as maintaining a nanoscale whose occurrence was confirmed by the appearance of the highly dispersed reinforcement phase in the examined Ti-TiB material example. The structural analysis of the sinters confirms the metal matrix composite arrangement and provides an additional quantitive data overview for the comparison of the processing conditions. The mechanical alloying examined in this work and the electrical current-assisted sintering approach allow in situ metal matrix composite structures to create their properties by careful control of the processing steps.