Metal Matrix Composite Samples Research Articles

Microstructure and mechanical properties of friction stir welded AZ31 magnesium alloy reinforced with ZrB2

Abstract Metal matrix composites (MMC) have advantages over polymer matrix composites such as high stiffness and strength, high-temperature resistance, better abrasion resistance, creep resistance, resistance to degradation by fluids, dimensional stability, and non-flammability. Metal matrix composites are used for various applications in the automotive, aerospace and sporting goods industries. The primary objectives of the current research work encompass the fabrication of Metal Matrix Composites (MMCs) AZ31 with 0.5%, 1.0% and 1.5% zirconium boride (ZrB2) nano-powder by the stir casting process, followed by welding through Friction Stir Welding (FSW). The metallographic analysis was carried out on the weldments of all cases. The macroscopic and microscopic analysis confirmed the defect-free weld joint. Tensile and hardness tests were conducted to study the mechanical properties of the materials. The tensile strength and the percentage of elongation increased with the percentage of ZrB2. But, after 1.0% addition of nano particles the strength decreased. The same pattern had been observed in both base and welded samples. The defect-free welding joints were fabricated with an efficiency of 79.1%, 79.7% and 77.7% for the materials with 0.5%, 1.0% and 1.5% nano powder, respectively. EIS and PDP tests were conducted in 3.5% NaCl to study the corrosion behaviour of base and welded materials. The corrosion tests on the base MMC samples showed that the corrosion resistance increased after the addition of ZrB2 nanoparticles. In addition, the corrosion resistance of all the welded samples improved compared with their respective base materials.

Mechanical and metallurgical characterization of B4C and SiC reinforced stir casted AA6061 hybrid MMC

The present work was the novel investigation of mechanical and metallurgical characteristics of stir casted AA6061 based metal matrix composites (MMC) and hybrid MMCs. The reinforcements utilized in the investigation were silicon carbide and boron carbide. The thirteen stir casted MMC and hybrid MMC samples were tested for ultimate tensile strength, microhardness, fractography and wear performance. The stir casting process had enhanced the reinforcement distribution within the aluminium matrix. The enhancement in ultimate tensile strength was observed due to the addition of reinforcements in increasing weight percentages with the hybrid MMC exhibiting peak ultimate strength which was a 32.17% improvement against the non-reinforced AA6061 alloy. The formation of reinforcement particulates had enhanced microhardness of the specimens with the peak microhardness observed for boron carbide reinforced MMC exhibiting microhardness 25.41% higher than the base alloy. The hybrid MMC exhibited ductile fracture with highest elongation corresponding to the highest ultimate tensile strength. The wear performance analysis revealed reduced wear rates for the particulate reinforced specimen with highest weight percentage of reinforcements.

Study on mechanical and micro-structural properties of aluminium matrix composite reinforced with graphite and granite fillers

Composites are gaining increasing popularity nowadays due to their wide range of applications and flexible design options. Aluminium Matrix Composites (AMCs) have garnered increasing attention in contemporary times as a subject of research. The inclusion of reinforcements in the metallic matrix results in improved stiffness, specific strength, wear resistance, creep resistance, and fatigue characteristics when compared to conventional engineering materials. In our study, we are employing a 6061 grade Aluminium alloy as the fundamental material, and augmenting it with Synthetic Graphite and Granite fine particles as strengthening agents. The Aluminium matrix composite is produced through the incorporation of synthetic graphite particles and granite dust into the molten aluminium via a Stir Casting Furnace utilising a bottom pouring technique at temperatures within the range of 850 to 950 °C. The Aluminium Metal Matrix composite samples is fabricated with varying reinforcement percentages relative to the base material. The distribution of particles within the Aluminium Matrix is analysed. Furthermore, the fabricated composites have undergone Tensile, Impact, Shear, and Micro hardness tests to assess the effects of incorporating reinforcements. All examinations conform to the standards set by ASTM. A comparative analysis is conducted between the mechanical properties exhibited by the original Aluminium alloy and the Aluminium metal matrix composites that have been manufactured.

Development of Determination Methodology of Electrical Conductivity of Titanium-based Composites

The Ti-based metal matrix composite samples are novel, fabricated by using high voltage electric discharge and spark plasma sintering processes. They have potential usage in the aviation industry. A research that allowed measuring an electrical conductivity of Ti-based composites was performed. A collinear four-point probe method was chosen for measurement of electrical conductivity. Needle-like probes were used to contact the tested sample. Other aspects of the measurement setup are discussed and selected according to relevant literature. A simulation was performed using COMSOL software to validate the measurement method. Furthermore, a simulation performed for contact force of the probes was performed. A 3D model of the measurement tool was created and designed. The measurement setup was tested and validated by using a copper sample. electrical resistance of Ti-based composite samples was measured, and electrical conductivity was calculated. Furthermore, samples were measured at different temperatures and resistivity dependence to temperature was presented. Experimental results are compared to similar research results.

Experimental study on mechanical properties of Al5083/ZrO2/B4C hybrid aluminum metal matrix composites

In this paper aluminium metal matrix composite samples are prepared by reinforcing B4C and ZrO2 in Al5083 using stir casting furnace. In this work, two types of AMMCs are prepared. In first type composite, different weight percentages (wt.%) of the nano reinforcement (ZrO2) are added from 0.6 to 1.8 in aluminium matrix. In the second composite, two nano reinforcements ZrO2 and B4C are combinedly added in the wt.% from 0.6 to 1.8 in AMMCs. The prepared composite samples are tested for their tensile strength, hardness, impact strength and wear rate. The hybrid composites show better values compared to ZrO2 composites for same weight percentages and thereby, weight of material could be reduced. Hardness increases with increase in wt.% of Zro2/B4C reinforcements compared to hardness of Zro2 composites for the same quantity of reinforcement. The impact Strength is high for hybrid composite and the low wear rate for same composite. The SEM study revealed that there is uniform distribution of reinforcements in the matrix material and also observed the better bonding between the base metal and the reinforcements. This material is more useful for aerospace application where high strength to weight ratio is required.

Tribological Behaviour of Al-2024/TiC Metal Matrix Composites

Pin-on-disk tests were performed to evaluate the wear behaviour of a 2024 aluminium alloy metal matrix composite (MMC) reinforced with 52 vol.% of TiC particles (Al-2024/TiC) in a fabricated and thermal-treated (T6) condition. The MMC was produced via pressureless infiltration of partially sintered TiC preforms with an average particle size of 1.1 μm at 1200 °C for 2 h under flowing argon. Microstructural and mechanical characterisation were carried out on both the monolithic alloy (MM) and the MMC with and without heat treatment. The effect of T6 heat treatment on the tribological behaviour of MMC has been investigated under dry sliding wear conditions under normal loads of 2, 5 and 10 N against ceramic α-Al2O3 and SAE 52100 steel spherical counterparts. Results indicate a substantial improvement in the microhardness (289–343 HV), hardness (25–34 HRC), and wear resistance of the MMC after T6 heat treatment (1 × 10−3 to 5 × 10−5 mm3/Nm). For a better understanding of the wear mechanisms, surfaces of the worn tracks were studied. Oxidation and abrasion were found as the dominant wear mechanisms in both MM and MMC samples. Even though MM exhibited a lower coefficient of friction (COF) (0.50–0.80), composites showed superior wear resistance by 5-fold higher than the base alloy.

Process study for directed energy deposition of 316L stainless steel with TiB2 metal matrix composites

In addition to laser powder bed fusion, directed energy deposition (DED) is also gaining interest as an effective metal additive manufacturing technique. Due to its system configuration, it is more efficient and flexible for materials development. Therefore, it can be used for processing of metal matrix composites (MMCs) through the use of powder mixture as feedstock. 316L stainless steel has high corrosion resistance, biocompatibility, and ductility. Several studies have shown the feasibility of using DED to process 316L stainless steel. The material properties of 316L stainless steel can be improved using reinforcement particles such as TiB2 to form MMCs. In this study, the effects of process parameters on microstructure and mechanical properties of 316L stainless steel reinforced with TiB2 (316L/TiB2) MMC were studied. The process parameters, including laser power, scanning speed, and hopper speed, were varied and analyzed using Taguchi L9 array. It was found that the process parameters have insignificant effect on the bulk density of the samples produced. Through this study, it is also found that tumble mixing was not suitable for the powder feedstock preparation for MMCs to be processed by DED. The microstructure of DED 316L/TiB2 MMC samples consists of columnar and equiaxed grains. Columnar grains were located within the layers while equiaxed grains were located at the interlayer zones. Fine sub-grains were also observed within these grains and their boundaries were enriched with molybdenum and chromium segregations. Precipitates containing titanium were also observed to segregate at the sub-grain boundaries. Finally, the Vickers microhardness of the DED 316L/TiB2 MMC was found to be similar to pure 316L stainless steel produced by DED.

Effects of Nano TiC on the Microhardness and Friction Properties of Laser Powder Bed Fusing Printed M2 High Speed Steel

In this work, TiC/M2 high speed steel metal matrix composites (MMCs) were prepared using the ball milling method and laser powder bed fusing process. By controlling the TiC content in TiC/M2HSS, the grain size, phase composition, and frictional wear properties of the samples were enhanced. The results showed that when TiC/M2HSS was supplemented with 1% TiC, the surface microhardness of the samples increased to a maximum value and the wear volume decreased by approximately 39%, compared to pure M2HSS. The hardness and friction wear properties of the TiC/M2HSS composites showed a decreasing trend as the TiC content increased, owing to an increase in internal defects in the samples, as a result of excess TiC addition. The physical phases of the TiC/M2HSS MMC samples prepared by LPBF were dominated by the BCC phase, with some residual FCC phases and carbide phases. This work explored the possibility of enhancing the frictional wear performance of TiC/M2HSS samples by controlling the TiC content.

Investigation of Ultrasonic Attenuation and Hardness Relationship in Ceramic-Metal Composites

In material characterization, they contain a large amount of information at the frequency obtained about the mechanical and physical properties of the material under investigation, thanks to shear waves during the longitudinal passage of ultrasonic waves from materials.In this study, an experimental study was carried out on metal matrix composite samples to examine the variation of some ultrasonic parameters such as wave attenuation coefficients. Ultrasonic longitudinal and shear attenuation values obtained in copper-silicon carbide composites were measured at 4 MHz using the pulse-echo technique. All of the produced samples were sintered at 1050 ºC using microwave sintering technique. The variation of the shear attenuation values with the longitudinal wave in the material with the % SiC volumetric percentages of the hardness in the samples were measured. The experimental results obtained are discussed and analyzed to develop a technique in ultrasonic nondestructive testing for microstructure determination. It contains a large amount of information in the frequency obtained about the mechanical and physical properties of the material examined by the passage of ultrasonic waves through the materials. In this study, an experimental study was carried out to examine the variation of some ultrasonic parameters such as wave attenuation coefficients on metal matrix SiC doped composite samples. Ultrasonic longitudinal and shear attenuation values of produced copper-silicon carbide composite samples were measured at 4 MHz frequency by pulse-echo technique. Variations of longitudinal and shear attenuation values and hardness with % SiC volume percentages were determined. The experimental results obtained are discussed and analyzed to improve the ultrasonic nondestructive testing method for microstructure determination.

Laser powder bed fusion of diamond/N6 MMCs enabled by Ni-Ti coated diamond particles

Metal matrix composites (MMCs) have received increasing attention and there is a growing interest in additive manufacturing (AM) of MMCs with complex shapes recently. However, it remains challenging to control the quality of composite powder for MMCs. In this study, the diamond particles are firstly coated with thin layers of Titanium and Nickel to ensure strong interface bonding with the Nickel matrix. The influence of ball milling parameters on the Ni-Ti coated diamond/N6 composite powder particles preparation and the effect of processing parameters during laser powder bed fusion (LPBF) on the densification of and defects in the fabricated samples are analyzed. In the ball milling stage, the results show that highly flowable composite powder particles for LPBF can be obtained under a ball milling time of 4 h, a speed of 250 rpm, and a ball-to-powder ratio of 2:1. With the optimized composite powder, a set of Ni-Ti coated diamond/N6 MMCs are further manufactured under the laser powers of 150, 160, and 170 W and scanning speed of 250 mm/s, the MMC samples have relative densities higher than 99%. Our study demonstrates the feasibility of manufacturing dense diamond/N6 and other similar MMCs with appropriate coating, ball-milling and LPBF parameters.

Study on Composition of Rice Husk Silica Reinforcement to Hardness and Microstructure of Recycling Milled AA7075

Metal matrix composites based on aluminium reinforced natural waste are a well-known material industry application because they can reduce environmental pollution. This paper presents the hardness and microstructure analysis of recycling milled aluminium (AA7075) at various composition of rice husk silica. Recycling milled AA7075 reinforced with rice husk burned at 1000°C at various composition i.e., 2.5, 5, 7.5, 10 and 12.5 wt.%, were investigated. Metal matrix composites samples were prepared by cold compaction method due to the lower energies consumption and operating cost compared to conventional recycling by casting. The results reveals that the hardness of metal matrix composites samples increased at increasing of rice husk silica up to 5 wt.%. The addition of rice husk silica increased the irregularities of pore shape and it resulted in higher porosity and random pore shapes compared to unreinforced metal matrix composites samples. Based on investigation of metal matrix composites samples, rice husk silica has good potential to improve the material behavior with appropriate composition of rice husk silica to metal matrix composite.

Macro-hardness and corrosion behavior of silicon carbide or boron carbide reinforced AA5052 MMC

Metal Matrix Composites (MMCs) enhance the mechanical and tribological properties according to the composition of the particulate reinforcement of Silicon Carbide (SiC) or Boron Carbide (B4C) and AA5052 aluminum alloy matrix. The MMC samples were fabricated by stir casting method of the liquid processing route. The same weight percentages (5 wt. %) and same particle size (63μm) of both SiC and B4C particulates are used to develop two different MMC samples. The hardness and corrosion tests were conducted to estimate the enhanced properties of the fabricated composites. The macro-hardness test and the immersion corrosion test were carried out by using a Vickers hardness tester at an applied load of 5kgf in accordance with ASTM E92 and a 3.5% NaCl solution in accordance with ASTM G31, respectively. With the help of optical microscopy, the corroded surfaces were analyzed. The results obtained from the investigation show that AA5052/B4C MMC gives better hardness and AA5052/SiC MMC shows higher corrosion rate compared to the other two samples.

WITHDRAWN: Ductility properties analyses in nano silicon particulate reinforcement on AZ91 Magnesium metal matrix composites using friction stir processing

This article has been withdrawn at the request of the author(s). The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

Influence of pre-alloying on Fe-Cu based metal matrix composite

A pre-alloyed powder (i.e., Fe70Cu30), and elemental metal powders (i.e. Fe and Cu) were selected to study the mechanical properties and microstructures of two groups of Fe-Cu based metal matrix composite (MMC) samples. One group had different Fe/Cu ratios, and the other group had a fixed Fe/Cu ratio with different molten state contents (MSCs). Bending strength, Rockwell hardness and relative density of the samples were tested first, and then SEM and EDS were employed to analyze fracture surfaces of the samples after three-point bending test. Test and observation results show that both Fe/Cu ratio and MSC are significant to the mechanical properties and microstructure characteristics of the Fe-Cu based MMC samples. The mechanical properties increase with the decrease of Fe/Cu ratio at first, but sharply drop when Cu becomes the main ingredient, with the best performance of 1200 MPa and 98 HRB at Fe/Cu ratio of 7:3. The effects of Fe/Cu ratio also indicate that the strengths of bonding interfaces are different, and in descending order are Fe-Fe, Fe-Cu and Cu-Cu respectively. Simultaneously, mechanical properties increase with the rise of MSC in general with the optimal interval of Fe/Cu ratio for impregnated diamond bits being between 8:2 and 3:7. Micro fracture morphologies of the Fe-Cu based MMC samples also indicate that their fracture mechanism can be divided into brittle, plastic and transcrystalline fractures with MSC being the determinant.

On the High-Temperature Flow Response of Friction Stir Processed Magnesium Metal Matrix Composites

AbstractIn the current work, multi-pass friction stir processing (FSP) was utilized to fabricate samples of fine-grained aluminum–zinc (AZ) magnesium alloy and its metal matrix composite (MMC). The microstructure and high-temperature tensile behavior of friction stir processed (FSPed) AZ31 and AZ31/SiC MMC at various strain rates in the range of 10−2 to 10−4 s−1 were investigated, and the fracture mechanisms of each condition were analyzed. The results verified that MMC samples exhibited a remarkable enhancement in microhardness. The evolution of inclined basal texture was observed after processing for both FSPed and MMC samples. The ambient temperature stress–strain response revealed that the formability of AZ31 has improved after friction stir processing, whereas high-temperature flow curves were discernibly sensitive to strain rate. Equiaxed deep dimples were detected on the fracture surfaces of FSPed samples, but decreased strain rate led to an increase in the number of dimples as attributed to the recrystallization of new grains.

Investigation on Tribological and Machining Characteristics of Al 7075/MWCNTs Nanocomposites

In the present research work, an attempt has been made to fabricate the aluminum metal matrix composite by stir casting method. Aluminum 7075 alloy is used as a matrix which is reinforced with multi-walled carbon nanotubes (MWCNTs) with varying 4 wt% fabricated through liquid-state method (stir casting). The machining was performed using EDM. Experiments were carried out to analyze microstructure, mechanical, tribological, and machining characteristics such as microhardness, tensile strength, wear rate, coefficient of friction, material removal rate, and surface roughness. Also, the samples were studied under a scanning electron microscope, energy dispersive X-ray analysis, and X-ray diffraction analysis to investigate the dispersion, chemical composition, and elemental analysis of multi-walled carbon nanotubes in Al7075. The microscopic study of metal matrix composite samples shows a good dispersion of MWCNT into Al7075. Results show that the microhardness and tensile strength increase by 6% and 25%, respectively. The wear rate and coefficient of friction of composites are decreased by 39% and 48% at a sliding speed of 3 m/s.

Utilisation of fly ash as a potential reinforcement material for better mechanical properties of Aluminum

The remarkable strength and durability characteristics found in lightweight alloys-based Metal Matrix Composites (MMC) assisted in enhancing their widespread use in automobile, aircraft, and marine sectors. The present study consists of utilizing a conventional stir casting setup for fabricating Aluminium-based MMCs having fly ash as reinforcement. The fly ash was reinforced with an aluminum matrix in proportions: 2, 4, and 6 % to get three different homogeneous samples of MMCs. The prepared samples were examined for microstructure and mechanical characterization. The MMCs samples exhibited successful incorporation and homogeneous dispersion of fly ash particles. The fly ash addition assisted in enhancing the hardness and decrease in strength of aluminum MMCs.

Investigation on mechanical, wear, and machining characteristics of Al 7075/MWCNTs using the liquid state method

In the present research work, an attempt has been made to fabricate the aluminum metal matrix composite by the stir casting method. Aluminum 7075 alloy is used as a matrix which is reinforced with multi-walled carbon nanotubes (MWCNTs) with varying percentage (0 wt.%, 1.0 wt.%, 2.0wt.%, and 3.0 wt.%). Experiments were carried out to analyze microstructure, mechanical, tribological, and machining characteristics such as microhardness, tensile strength, wear rate, coefficient of friction, material removal rate (MRR), and surface roughness (Ra). Also, the samples were studied under a scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), and X-ray diffraction analysis (XRD) to investigate the dispersion, chemical composition, and elemental analysis of multi-walled carbon nanotubes in Al 7075. The microscopic study of metal matrix composite samples shows a good dispersion of MWCNT into Al 7075. Results show that the microhardness and tensile strength increase by 6% and 25%. The wear rate and coefficient of friction of composites are decreased by 39% and 48% at a sliding speed of 3 m/s. In addition, the metal removal rate decreases by 40% and the surface roughness enhanced by 38% respectively.

From Ni–P Metastable Alloy Nanoparticles to Bulk Submicrometer Grain-Sized MMCs with Tunable Mechanical and Magnetic Properties

In this study, submicrometer grain-sized metal matrix composites (MMCs) based on nickel were elaborated via a bottom-up strategy combining the polyol process and a non-conventional heat treatment route. First, four sets of nano-sized Ni–P metastable alloy nanopowders with an average particle size centered at 50, 100, 130, and 220 nm were prepared by the polyol process modified by the addition of hypophosphite (strong reducing agent) and heterogeneous nucleation using silver nitrate and platinum salt (nucleating agents). The heat treatment step was realized by reactive spark plasma sintering (R-SPS) at identical heat treatment conditions (600 °C, 53 MPa, and 10 min as holding time). R-SPS transformed the Ni–P metastable alloys into bulk submicrometer grain-sized MMCs with Ni as the matrix and Ni3P as the reinforcement. Mechanical and magnetic properties of the four MMC samples were found to be closely related to the grain size of the Ni matrix, which varied from 247 to 638 nm. Yield stress, maximum stress, and coercive field increased when the grain size decreased, while plastic strain and magnetization saturation decreased. The reinforcement Ni3P phase enhanced the mechanical characteristics of the composite. Crossover behavior was observed at around 350 nm Ni grain size, where a ductile and soft magnetic composite was tuned into a hard mechanical and semi-hard magnetic one.

Microstructure and mechanical properties of silicon carbide particle reinforced aluminium 6101 metal matrix composite produced by two-step stir casting

This paper provides an analysis of microstructure and mechanical properties of Al6101 metal matrix composite reinforced with silicon carbide particles. In this study, the Al6101-SiC metal matrix composite samples prepared using two-step stir casting are used to assess mechanical properties by conducting tests on a Universal Testing Machine and Vicker’s hardness tester. Mechanical properties like yield strength, shear strength and, hardness number show an increasing trend with an increase in the weight percentage of silicon carbide. However decrease in yield strength and shear strength is observed in samples containing 15% silicon carbide by weight. The ductility of the developed metal matrix composite found to be decreased with an increase in weight % of silicon carbide. The microstructure tests of the developed composite conducted using scanning electron microscopy indicate almost homogeneous distribution of reinforcement particles. Particle accumulation, shrinkage cavities are also found at some regions. Energy dispersive spectroscopy tests indicate element percentage in composite samples. The phases formed are identified by X-ray diffraction tests.