Reinforced Metal Matrix Composites Research Articles

Investigation of suitable graphene reinforcements for copper based PIM feedstock

Abstract Graphene holds a remarkable potential as a reinforcement material for copper matrix due to its outstanding mechanical and electrical properties. However, noticeable increment in performance of graphene reinforced metal matrix composites is restricted due to inhomogeneous distribution and weak interfacial interaction between graphene reinforcement and metal matrix. Poor dispersion of graphene nanoplatelets can be attributed to absence of functional groups on graphene sheets, graphene oxide in contrast holds a large number of functional groups on its surface and edges, which make it dispersible in a wide range of matrices. In this research work, we investigate potential of graphene nanoplatelets and graphene oxide as reinforcement for copper based feedstock. During this study, two different approaches, solvent based mixing and copper grafting, have been employed as dispersion methods. A radical approach for incorporation of graphene in metal matrix is also devised, by taking benefit from functional nature of graphene oxide and anchoring copper particles on graphene oxide sheets. Successful growth of copper particles along with simultaneous reduction of graphene oxide have been observed by using scanning electron microscopy and infrared spectroscopy analysis. Copper particles as intercalation species present a viable potential to resist re-agglomeration of graphene sheets while enhancing the interfacial interaction between copper matrix and graphene at the same time. Copper graphene nanocomposite can potentially be used as a reinforcement for copper based powder injection molding feedstock.

Wear and corrosion behaviour of titanium carbide reinforced metal matrix composites for automobile brake disc application

The wear and corrosion behaviour of aluminium silicon (Al-Si) alloy with titanium carbide (TiC) were investigated in this article. Initially automobile brake discs of a passenger car were fabricated by stir casting method with 10 wt. % of TiC in Al-Si alloy. A small part cut from the brake shoe used as a pin to slide against MMC and Grey cast iron in dry condition. It was found from the results that the wear resistance and coefficient of friction for TiC reinforced MMC is better than iron. Experimental values of wear agree very closely with simulation results. Potentiodynamic polarisation measurements exhibits that the corrosion resistance decreased with increasing TiC weight percentage. However, the hardness of the samples was increased. SEM analysis showed more no. of corrosion spots in samples with 10 wt. % of TiC. XRD analysis revealed that the presence of reinforcement in matrix affect the corrosion rate.

Wear and corrosion behaviour of titanium carbide reinforced metal matrix composites for automobile brake disc application

The wear and corrosion behaviour of aluminium silicon (Al-Si) alloy with titanium carbide (TiC) were investigated in this article. Initially automobile brake discs of a passenger car were fabricated by stir casting method with 10 wt. % of TiC in Al-Si alloy. A small part cut from the brake shoe used as a pin to slide against MMC and Grey cast iron in dry condition. It was found from the results that the wear resistance and coefficient of friction for TiC reinforced MMC is better than iron. Experimental values of wear agree very closely with simulation results. Potentiodynamic polarisation measurements exhibits that the corrosion resistance decreased with increasing TiC weight percentage. However, the hardness of the samples was increased. SEM analysis showed more no. of corrosion spots in samples with 10 wt. % of TiC. XRD analysis revealed that the presence of reinforcement in matrix affect the corrosion rate.

Effect of hot extrusion on mechanical behaviour of boron nitride reinforced aluminium 6061-based metal matrix composites

In this present investigation Al 6061-based BN reinforced metal matrix composites were developed with 6 and 9 wt% of boron nitride. The Al 6061 was chosen as base material owing to its superior formability, light weight and moderate strength. Boron nitride was used as reinforcement keeping in mind its excellent wear and corrosion resistance along with superior strength and thermal properties. The stir casting method was adopted for development of composites since it is most flexible and universally accepted method for preparing castings economically. The developed composites were subjected to extrusion process. Mechanical properties were tested both before and after the extrusion to study the impact of extrusion process on properties of composites. It was observed that hardness and tensile strength of both casted and extruded samples were improved by the addition of the BN reinforcement. Whereas ductility of samples reduced with the increase of boron nitride concentration. Scanning electron microscopy (SEM) is used to identify the distribution of boron nitride (BN) and to study the fractured surfaces of Al 6061-BN metal matrix composites.

Effect of hot extrusion on mechanical behaviour of boron nitride reinforced aluminium 6061-based metal matrix composites

In this present investigation Al 6061-based BN reinforced metal matrix composites were developed with 6 and 9 wt% of boron nitride. The Al 6061 was chosen as base material owing to its superior formability, light weight and moderate strength. Boron nitride was used as reinforcement keeping in mind its excellent wear and corrosion resistance along with superior strength and thermal properties. The stir casting method was adopted for development of composites since it is most flexible and universally accepted method for preparing castings economically. The developed composites were subjected to extrusion process. Mechanical properties were tested both before and after the extrusion to study the impact of extrusion process on properties of composites. It was observed that hardness and tensile strength of both casted and extruded samples were improved by the addition of the BN reinforcement. Whereas ductility of samples reduced with the increase of boron nitride concentration. Scanning electron microscopy (SEM) is used to identify the distribution of boron nitride (BN) and to study the fractured surfaces of Al 6061-BN metal matrix composites.

Microstructure-based modelling of fracture of particulate reinforced metal matrix composites

This paper aims to develop a microstructure-based model to describe the material deformation and fracture of the particulate reinforced metal matrix composites. The A359/SiC composite was used as a material example. The most important factors, such as particle morphology, distribution and fracture, matrix deformation and failure, and particle-matrix debonding, were comprehensively integrated into the modelling. Relevant experiments were also conducted. It was found that such a microstructure-based model can capture the major material deformation and failure mechanisms. The particle geometry and distribution can be described by normalized shape factor and clustering distance. Stress concentrations occur at the clustered particles, especially at the sharp corners, particle-matrix interfaces and the edges along the loading direction. The stress in the matrix is much lower than that in the particles and concentrates along 45° to the loading direction. Matrix-particle debonding is not noticeable. Particle fracture happens near its sharp corners, while matrix failure initiates around the particle crack tips and propagates to connect the microcracks caused by particle fracture, or through the area with high stress/strain concentration, leading to the fracture of the whole workpiece.

Electroless carbon fibers: A new route for improving mechanical property and wettability of composites

For carbon fiber reinforced metal matrix composites, there are many potential problems such as severe agglomeration of carbon fibers (CFs), their poor interfacial wettability with the matrix, and poor mechanical strength. To solve these problems, we proposed to use electroless plating to coat a layer of Ni onto the CFs, and then studied their interfacial structures, fracture strain/strength and wettability. The coated Ni layer was uniformly distributed onto and well bonded with the CFs. The maximum strain of the CFs coated with the Ni layer was increased by 23.4%, though their average fracture strength was slightly decreased from 3.5 GPa to 2.25 GPa. The wettability of the Ni-coated fiber was significantly improved, verified from testing results using both a dip coating method and a fiber reinforced composite simulation test.

Distribution of stress and strain between adjacent particles in particulate reinforced metal matrix composites

Abstract The distribution of stress and strain between adjacent particles in particulate reinforced metal matrix composites was investigated using cohesive zone models. It is found that the strain of the composite is concentrated in the matrix, and there is a region with higher strain along the loading path, which can promote the formation of a void near the particles pole. The stress and strain in matrix near the particles gradually decrease with the increase of the distance between particles. And it is calculated that there is a critical distance within which the stress and strain fields of the neighboring particles can influence with each other. This critical distance increases with the increase of particle size. It is also found that the angle between the tensile direction and the center line of particles plays an important role in the stress and strain distribution. The model with the angle of 0° has the greatest influence on the distribution of stress and strain in the matrix, while the model with the angle of 45° has the least influence on the distribution of stress and strain in the matrix.

Chemical Stability of Ti₃C₂ MXene with Al in the Temperature Range 500⁻700 °C.

Ti3C2Tx MXene, a new 2D nanosheet material, is expected to be an attractive reinforcement of metal matrix composites because its surfaces are terminated with Ti and/or functional groups of –OH, –O, and –F which improve its wettability with metals. Thus, new Ti3C2Tx/Al composites with strong interfaces and novel properties are desired. To prepare such composites, the chemical stability of Ti3C2Tx with Al at high temperatures should be investigated. This work first reports on the chemical stability of Ti3C2Tx MXene with Al in the temperature range 500–700 °C. Ti3C2Tx is thermally stable with Al at temperatures below 700 °C, but it reacts with Al to form Al3Ti and TiC at temperatures above 700 °C. The chemical stability and microstructure of the Ti3C2Tx/Al samples were investigated by differential scanning calorimeter, X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy.

Graphene oxide/Al composites with enhanced mechanical properties fabricated by simple electrostatic interaction and powder metallurgy

Graphene has attracted great attention as an ideal reinforcement in Al matrix composites. However, there are still challenges limiting the performance of the composites, such as the homogenous distribution of graphene in Al matrices. In this paper, graphene oxide/aluminum (GO/Al) composites with enhanced mechanical properties were fabricated by electrostatic interaction and subsequent powder metallurgy method. Firstly, GO was homogenously coated on the surface of micro-sized spherical aluminum powders by electrostatic interaction between GO and aluminum in water/ethyl alcohol solution with a little HCl acid. Then the mixture of GO/Al composite powders with different GO content (0.15 wt%, 0.3 wt%, 0.6 wt%) were cold compacted and sintered at 580°Cfor 3 h. Compared with unreinforced Al, the composite with only 0.3 wt% GO achieved 73.9% enhancement in ultimate tensile strength, which was up to 167 MPa with elongation of 11.5%. Three points bending test was also carried out for composite with 0.3 wt% GO, and the flexural strength reached 224 MPa. Fractured morphology displayed a ductile break and graphene oxide pull-out was detected at the edges of dimples. It was expected that this work could offer a simple method to prepare graphene reinforced metal matrix composites.

Interactive study on phase morphology and mechanical characteristics of diffusion annealed and age hardened Al7075–steel powder reinforced metal matrix composites

This paper expounds the effects of diffusion annealing and age hardening heat treatments on the phase morphology and mechanical properties of Al7075–eutectoid steel powder (0.8 wt% carbon steel) reinforced composites. Eutectoid steel powder ranging from 55–70 μm is selected due to its ability to improve the bulk hardness of the composite. In the present study three different weight fractions of eutectoid steel powder composites are prepared by conventional stir casting process. The material is cast in the form of rods inside the permanent stainless steel mould from where some samples are cooled in still air to room temperature. From these samples some are diffusion annealed from isothermal holding of 6 h i.e., above recrystallization temperature (600 °C) followed by boiling water quench and few are subjected to age hardening for a fixed time duration of five hours. Age hardening is carried out at solutionising temperature 560 °C tailed by aging at two temperatures 100 °C and 180 °C independently. All the samples in each category are subjected to critical property characterization and the phase arrangement information are characterized by scanning electron microscopy. From the analysis of microstructure and destructive tests, it is clear that the as-cast (stir-cast) samples display dendritic segregations with wider grain boundary area, is responsible for the inferior mechanical properties. It is also found out that diffusion annealing and age hardening heat treatments eliminates micro-segregation and improve mechanical properties of Al7075–eutectoid steel powder reinforced composites. It is concluded that chemical inhomogeneity in dendrites can be eliminated by selecting the suitable heat treatment with proper heat treatment parameters.

Optimal design of a bio-inspired self-healing metal matrix composite reinforced with NiTi shape memory alloy strips

Utilizing smart materials such as shape memory alloys as reinforcement in metal matrix composites is a novel method to bio-mimic self-healing. This study aims to investigate the influence of design factors of a self-healing metal matrix composite by employing the Taguchi method for designing of the experimental procedure. Three design factors, each in three levels, were studied simultaneously according to L-9 standard Taguchi orthogonal array to determine the optimal level of each factor in mechanical properties enhancement with a reduced number of experiments. Composite specimens were fabricated from Sn-13 wt.% Bi alloy as matrix and nickel–titanium shape memory alloy strips as reinforcement with gravity casting process. Matrix alloy was melted and casted in a preheated metallic mold in which SMA strips were installed in various quantities (one, two, or three strips) and different pre-strains (0%, 2%, or 6%). After fabrication of the specimens, a tensile test was conducted until fracture to specify mechanical properties. Then, specimens were placed in a furnace in three different temperatures (170°C, 180°C, and 190°C) to activate the shape memory effect of strips and achieve crack closure and healing. Specimens were tensile tested again after healing to calculate the amount of healed properties and healing efficiency. Results show that using three strips with 6% of pre-strain and applying 190°C healing temperature can maximize the ultimate tensile strength efficiency. Also, the existence of one strip, 0% pre-strain, and 190°C healing temperature creates the best circumstances for healing ductility.

Effect of tool nose radius and tool wear on residual stresses distribution while turning in situ TiB2/7050 Al metal matrix composites

In situ TiB2/7050 Al matrix composite is a new kind of particle reinforced metal matrix composite. With in situ synthesis method, a better adhesion at interfaces is achieved and hence improves mechanical properties. However, due to the presence of hard TiB2 ceramic particles, the tool wear problem is severer while machining TiB2/7050 Al composites compared with traditional metallic alloy. In order to have a deeper understanding of the residuals stress distribution during machining metal matrix composites, this paper investigates the effect of tool nose radius and tool wear on the residual stress distribution during turning TiB2/7050 Al composites. Four CBN tools with different tool nose radius (0.4, 0.6, 0.8, and 1.0 mm) are used. The cutting force and residual stress distribution beneath the machined surface have been analyzed when the CBN tools are new or worn (0.26 mm VB). The results show that the residual compressive stress distribution is always obtained on the machined surface and subsurface no matter the tools are new or worn. The larger tool nose radius causes the increase of cutting force, lower surface residual compressive stress, and deeper residual stress penetration layer. As the tool wear, the location of maximum residual compressive stress transfers from the machined surface to the deeper subsurface. Compared with the tool nose radius, the tool wear has more significant influence on the cutting force and residual stress distribution.

Microstructure evolution of in-situ (Ti,W)C-Al2O3 particle-reinforced alloy fabricated by gas tungsten arc cladding

This paper reports the fabrication of TiC-Al2O3 or (Ti,W)C-Al2O3 ceramic reinforced metal matrix composites (MMC) using gas tungsten arc cladding. For fabrication of the MMC, an in-situ reaction was used to reduce oxides by employing C and Al as reducing materials during the cladding process, and the strengthened particles formed on the surface by solid state reaction were then grown through interaction in the metal matrix. The reactions forming phases in this system were subsequently examined through thermodynamic calculations. Results showed that TiC and Al2O3 peaks were observed in XRD for the reduction of TiO2 and WO3 by Al and C. The cladded hardfacings were covered by a composite slag zone, which consisted of Al2O3 particles embedded in Al and Ti based ceramic matrix, and that carbide particles such as TiC and (Ti,W)C were distributed intensively inside the MMC zone. Most of the TiC particles in the MMC zone had a slow growth rate because the interface controlled the growth; however, some particles that highly interacted with metals exhibited a dendrite structure. (Ti,W)C particles without dendrite growth formed a spherical shape, and the size of the particles was controlled by diffusion of the solute. Following the dissolution and precipitation process, (Ti,W)C-strengthened particles were found to have a sintering-like core/rim structure. Furthermore, the microhardness of the clad obtained was 600–900 HV0.2, which is significantly better than that obtained with commercial TiC powder.

Finite-Element Modeling of Particle Size Effect on Mechanical Properties of SiCp/Fe Composites

Particle size has a significant effect on mechanical properties of particle reinforced metal matrix composites (PRMMCs). Here, the effect of particle size on mechanical properties of SiCp/Fe composite has been studied using a finite element (FE) model incorporated with the Taylor-based nonlocal theory (TNT) of plasticity, where the tested particle size is 5, 10, 16, 21, 28 and 40μm, respectively. The results indicate that the TNT-FE model overcomes the shortage of the traditional FE model, which cannot deal with the intrinsic size effect. With the particles of 20 vol.%, the simulated flow stress of the iron matrix composite reinforced by 16μm SiC particles is the highest and then follows the order of 28 > 5 > 10 > 21 > 40μm particle reinforced ones, close to the tendency of experimental results. A large area of compressive stress zone is observed in the matrix near the particles in the composites reinforced by 16 and 28μm particles, which implies that the matrix can be well protected during loading, so that the load-bearing capability is better. The purpose is to optimize mechanical property of SiCp/Fe composite by adjusting particle size and eventually to design PRMMCs from microstructural control.

Central Composite Experimental Design Applied to the Dry Sliding Wear Behavior of Mg/Mica Composites

A five-level four-factor central composite design multivariable model was constructed for the evaluation of the combined effect of operating parameters such as percentage reinforcement (0–10%), load (5–25 N), sliding speed (1–5 m/s), sliding distance (500–2500 m) on the wear rate of mica reinforced metal matrix composites. The microwave-assisted powder metallurgy technique was used to fabricate the composites. The wear tests were performed according to statistical designs to develop an empirical predictive regression model. The interaction of percentage reinforcement and sliding distance indicated the significant impact on wear rate. The statistical analysis confirms the optimum composition of mica blends leading to the best possible wear rate. No rapid wear region was identifiable in the morphology of worn composite surfaces.

Toughening mechanisms of solution-treated SiCp/6061 aluminum matrix composites fabricated via powder thixoforming

Abstract

Preparation and mechanical properties of CNTs-AlSi10Mg composite fabricated via selective laser melting

Selective laser melting（SLM）exhibits unique advantages in the fabrication of micro- and nano-particle reinforced metal matrix composites. Here, we studied the effect of scan speed on the microstructures and mechanical properties of carbon nanotubes (CNTs) reinforced AlSi10Mg composites printed by SLM. To investigate the effects of CNTs on SLM parts, single track scans, single layer scans and test parts of 1 wt%CNTs/AlSi10Mg were created via SLM. The results indicated that as the scan speed increased, the width of the scan line generally decreased and the height of the scan line generally increased. The mechanical properties of the test parts increased at first but then decreased with increasing scan speed. A laser scan speed of 1300 mm/s produced test parts with the highest mechanical properties: the relative density, hardness and tensile strength were 98.53%, 143.33 HV and 499 MPa, respectively. The hardness increased by approximately 10%, and the tensile strength increased by approximately 20% compared to those values exhibited by the unreinforced AlSi10Mg. The CNTs were detected in the fabricated parts. It was found that the CNTs were distributed along the boundaries of the cells of AlSi10Mg. Some of the CNTs reacted to Al4C3 during the SLM process. The combination of CNTs and Al4C3 created a pining effect, while the CNTs still maintained their tubular structure and played a role in loading; this improved the hardness and strength of the matrix material.

Effects of Direct Current on the Wetting between Molten Al and a Graphite Substrate

Graphite fiber attracted much attention in the area of aluminum based composite due to its low density and high strength. However, one of the major drawbacks in fabricating graphite reinforced metal matrix composites (MMCs) is that aluminum generally does not wet graphite. Therefore, it is difficult to impregnate the graphite fiber in molten aluminum. The application of external electric power has been recently reported as a promising way to improve the wettability. The effect of an electric current on the wettability of molten Al on graphite has not been investigated. The effects of electric current, density of sample and heating time on wettability, thickness of product, and microstructure were investigated. The wettability remarkably improved utilizing electric current due to a larger formation of Al4C3 per unit time from electromigration. The wettability of molten Al on graphite substrate is better with an applied negative current and with lower relative density of sample. Key words: wettability, Al4C3, electric current, aluminum, graphite

Multi Response Optimization of AWJM Process Parameters on Machining TiB2 Particles Reinforced Al7075 Composite Using Taguchi-DEAR Methodology

The importance of synthesizing particles reinforced metal matrix composites is increasing owing to their distinct physical properties. The machining of such composites is a tedious process due to its higher strength. In the present study, an endeavor has been made to investigate the influence of process parameters in abrasive water jet machining process while machining TiB2 particles reinforced Al7075 composite. Water jet pressure, transverse speed and standoff distance have been considered as input parameters to evaluate the performance measures such as material removal rate, surface roughness and taper angle in the machining process using Taguchi-DEAR methodology. From the experimental investigation, it has been found that water jet pressure has higher influence on determining performance measures in AWJM process owing to its importance on determining impact energy. The optimal process parameters combination has been found as water jet pressure (280 MPa), transverse speed (345 mm/min) and standoff distance (4 mm) among the chosen process variables and evaluated using confirmation test with 1.2% of deviation from mean MRPI value.