Magnesium Metal Matrix Composites Research Articles

Mechanical Characterization and Machining of MgAZ91D/SiC/Al2O3MMC by Squeeze Cast Method

In the automotive industry, the high surface finish and superior mechanical property materials are prepared with the help of the squeeze casting process. The paper investigates on the chosen materials of MMC cast using magnesium alloy (Mg-AZ91D) reinforced with various %wt of silicon carbide (SiC) also aluminum oxide (Al2O3) of nano particulates (20 nm). The preferred squeeze casting technique produces magnesium matrix composites along with silicon carbide (SiC) and aluminum oxide (Al2O3) particulates direct to an absolute drenched of inside the liquefy magnesium of hybrid metal matrix composite. Using CNC lathe and orthogonal array (L9), Magnesium metal matrix composites (Mg-AZ91D) are machined. To determine Metal Removal Rate (MRR) and Surface roughness (Ra) with various input parameters having the CNC lathe. Magnesium metal matrix composites (Mg-MMC) also, comparing the results with the unreinforced magnesium alloy with reinforcement of silicon carbide (SiC) and aluminum oxide (Al2O3) of nano particulates, Mechanical properties of the Magnesium metal matrix composite (Mg-MMC) and optimal machining parameters are evaluated.

Recent studies on particulate reinforced AZ91 magnesium composites fabricated by Stir casting – A review

Magnesium Metal Matrix Composites (Mg MMC) have been the focus of consideration by many researchers for the past few years. Many applications of Mg MMCs were evolved in less span of time in the automotive and aerospace sector to capture the benefit of high strength to weight ratio along with improved corrosion resistance. However, the performance of these materials in critical conditions is significantly influenced by several factors including the fabrication methods used for processing the composites. Most of the papers addressed all the manufacturing strategies of Mg MMC but no paper was recognized as a dedicated source for magnesium composites prepared through stir casting process. Since stir casting is the least expensive and most common process in the preparation of composites, this paper reviews particulate based Mg MMCs fabricated with stir casting technology. AZ91 series alloys are considered as the matrix material while the effect of different particle reinforcements, sizes , weight fractions on mechanical and tribological responses are elaborated in support with micro structural examinations. Technical difficulties and latest innovations happened during the last decade in making Mg MMCs as high performance material are also presented.

Review of Magnesium Metal Matrix Composites

In recent years, Magnesium Metal Matrix Composites (Mg-MMC) plays a significant part in an extensive application such as chemical, automotive and aerospace application as because of its lightweight structural and low density properties. In this present investigation, the literature review of Mg-MMCs study includes, reinforcing substantial, processing techniques, Characterization, tribological and mechanical behavior of Mg-MMCs. Furthermore, the CNT, Carbonaceous, Fullerene, SiC, Al2O3, TiC, B4C, Graphenereinforced Mg-MMC articulates are explained in this study. Consequently, the mechanical behavior of tensile strength, hardness, compressive strength and tribological properties of wear rate and corrosion performance was analyzed for various state of the art methods. From the observation, it shows that the ceramic reinforcing increases the hardness and strength of the material. Nevertheless, the ductility was diminished, yet, the ductility and strength of Mg-MMCs can enhance by the titanium based metallic reinforcement.

Recent Developments in Magnesium Metal-Matrix Composites for Biomedical Applications: A Review.

Recently, there is a growing interest in developing magnesium (Mg) based degradable biomaterial. Although corrosion is a concern for Mg, other physical properties, such as low density and Young's modulus, combined with good biocompatibility, lead to significant research and development in this area. To address the issues of corrosion and low yield strength of pure Mg, several approaches have been adopted, such as, composite preparation with suitable bioactive reinforcements, alloying, or surface modifications. This review specifically focuses on recent developments in Mg-based metal matrix composites (MMCs) for biomedical applications. Much effort has gone into finding suitable bioactive, bioresorbable reinforcements and processing techniques that can improve upon existing materials. In summary, this review provides a comprehensive overview of existing Mg-based composite preparation and their mechanical and corrosion properties and biological responses and future perspectives on the development of Mg-based composite biomaterials.

Fabrication and characterization of Magnesium Metal Composite by Stir Casting

In Automotive and Aerospace industries, the demand for lighter materials is increasing exponentially. The main advantage of Magnesium Metal Matrix Composites over Aluminium Metal Matrix Composites, there is an additional 15-20% weight saving without having to compromise on properties. Metal matrix composites reinforced with Boron carbide and molybdenum disulphide have significant advantage over conventional materials. Generally, these reinforcements are used to improve the hardness and tensile strength of metal matrix composite. In this study, we have performed three castings each on magnesium alloy (A14Z1, A17Z1, and A19Z1) and composites with reinforcements of 2.5% Boron Carbide by stir casting method. Mechanical test like Rockwell hardness were conducted to find hardness of the specimen. The Microstructure was observed through an Optical Microscope. The comparative study of these samples with and without reinforcement were carried out and analyzed. The results showed that there is an appreciable increase in mechanical and metallurgical properties of new magnesium novel composite material used in this investigation.

Experimental studies on magnesium metal matrix composites processed by Twist Extrusion

Recently magnesium alloys and magnesium composite were widely used due to their good strength to weight ratio. These materials find its applications in the bio-medical and in aviation industries. The aim of this study is to twist extrude the hybrid magnesium composite. The magnesium AZ91 alloy is used matrix medium and it was reinforced with 2%SiC and 1.5% B4C. The twist extrusion was carried out in a split die with a slope angle of 54°. The composite is prepared by the bottom pouring method. The number of passes is limited to one, as adding the reinforcement increases the brittleness of the composites. The twist extrusion of the composite resulted in a porosity free sample. Hardness was measured by Macro-Vickers tester and ASTM A370 standard was used for the tensile test. Results indicate an increase 26.6% in strength and 38.5% hardness of the twist extruded composite.

EXPERIMENTAL INVESTIGATION OF DRY SLIDING WEAR BEHAVIOUR OF STIR CASTED AZ31 MAGNESIUM ALLOY-CASIO3 METAL MATRIX COMPOSITES

Metal matrix composites (MMCs) became one of the obligatory material in the transportation sector where Magnesium MMCs are in high demand due to their exclusive properties like low density, good wieldable, recyclable, and casting. In the present work, wear behavior of AZ31 magnesium alloy added by calcium silicate (CaSiO3) as additive of various compositions of its weight percentage from 0 to 8% is determined and tested under dry sliding condition. After experimentation, results revealed that the sample S-3 which comprises 4% CaSiO3, shows the minimum pin temperature of 33.1 0C. In terms of frictional force, sample S-4 which has 6% CaSiO3, shows a least frictional force of 4.81 N. The sample S-2 formed by 2% CaSiO3 shows the highest value of 14.1 N of frictional force. By comparing the coefficient of friction value, the specimen sample S-4 displays the least friction value of 0.160 µ and sample S-2 exhibits the highest value as 0.470 µ. Wear occurred between pin and disc is observed as 292 µm for sample S-2 which is low compared to sample S-4 of 324 µm. By consolidation of results, the sample S-4 shows better performance in terms of force, coefficient of friction, and pin temperature concerning time.

Abrasive wear behavior of WC nanoparticle reinforced magnesium metal matrix composites

In this study, abrasive wear characteristics of AZ31-WC nanocomposites with varying weight percentage of nanoparticles (0, 0.5, 1, 1.5 & 2) are examined. AZ31-WC nanocomposites have been fabricated by ultrasonic vibration assisted stir casting method. Optical microscopy and scanning electron microscopy are employed to perform characterizations of cast composites. Density and micro hardness of nanocomposites are also investigated. Effect of abrasive grit size and sliding distance on abrasive wear behavior and friction behavior of nanocomposites are evaluated using pin-on-disc tribotester. Worn surfaces are studied with the help of 3D optical surface plotter, SEM and EDAX to find dominant wear mechanism at several experimental conditions. Microscopic observations disclose that distribution of WC nanoparticles is uniform throughout the matrix. Density and micro hardness increase with increasing percentage of WC nanoparticles. Moreover, significant improvement in wear resistance and friction behavior is observed by incorporation of WC nanoparticles. Wear resistance of Mg-2WC nanocomposite is improved around 56% than base alloy when tested with 400 grit SiC paper and 50 mm track diameter. Higher grit size abrasive paper exhibits less wear in composites. 3D Surface plots of worn surfaces show that, surface roughness is decreased with increasing wt% of WC. Surface roughness of worn surface of Mg-2WC nanocomposite tested with 800 grit, 50 mm track diameter has 35.06% less surface roughness than Mg-2WC nanocomposite tested with 400 grit, 50 mm track diameter. Investigation of worn surfaces discloses dominant mechanisms as abrasion, adhesion and delamination at several experimental conditions.

Investigation of severe plastic deformation effects on microstructure and mechanical properties of WS2/AZ91 magnesium metal matrix composites

AZ91 reinforced with four different concentrations (0,0.3,0.6,1)wt% of WS2 micro particles were fabricated using stir casting method. The samples were deformed by equal channel angular pressing (ECAP) after homogenization. The scanning electron microscopy and X-ray diffraction were used to investigate the microstructure and phase composition respectively. The results reveal that rod-like precipitates produced during the homogenization process are refined and bounded in the grain boundaries by the combined effect of WS2 enrichment and increasing number of passes of ECAP. The needle precipitates are eminent in 1pass 0.3 wt%WS2/AZ91. The β-Mg17Al12 and extracted Al particles are dissolved and secondary phases are produced by dynamic recrystallization after 2pass 1 wt%WS2/AZ91. The maximum crystallite size and microstrain distribution have been observed for 1pass 0.6 wt%WS2/AZ91. The mechanical properties investigation represents that 2pass 0.6 wt%WS2/AZ91 has optimal yield strength and ultimate tensile strength. The (22.143)%, (44.735)% and (92) % increment in yield strength, ultimate tensile strength and elongation have been observed in 2pass 1 wt%WS2/AZ91 compared with homogenized monolithic AZ91 alloy respectively. The maximum young's modulus (6696.218MPa) has been found for 1pass homogenized WS2/AZ91 and minimum (4108.165MPa) for homogenized 0.6 wt%WS2/AZ91. The ECAP deformed 1pass 0.3 wt%WS2/AZ91 exhibits the maximum strain hardening rate. The YTS, UTS, and elongation are (30.41) %, (47.6) % and (51.9)% increased after 2pass-0.6 wt%WS2/AZ91.

Graphene nanoplatelets-reinforced magnesium metal matrix nanocomposites with superior mechanical and corrosion performance for biomedical applications

Magnesium (Mg) metal matrix composites (MMCs) reinforced with graphene nanoplatelets (GNPs) have been developed by powder metallurgy (PM). GNPs with different concentrations (0.1, 0.2, and 0.3 wt.%), layer thicknesses (5 nm and 9 nm), and particle sizes (15 µm and 5 µm) were dispersed into Mg powder by high-energy ball-milling processes. The microstructure and mechanical properties of the fabricated composites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy (RS), and compression tests. The corrosion resistance was evaluated by electrochemical tests and hydrogen evolution measurements. The cytotoxicity of Mg-GNPs composites was assessed using osteoblast-like SaOS2 cells. The results indicate that GNPs are excellent candidates as reinforcements in Mg matrices for the manufacture of biodegradable Mg-based composite implants. GNP addition improved the mechanical properties of Mg via synergetic strengthening modes. Moreover, retaining the structural integrity of GNPs during processing improved the ductility, compressive strength, and corrosion resistance of the Mg-GNP composites. Cytotoxicity assessments did not reveal any significant toxicity with the addition of GNPs to Mg matrices. This study demonstrates that Mg-xGNPs with x < 0.3 wt.%, may constitute novel biodegradable implant materials for load-bearing applications.

In situ infiltration synthesis and characterization of magnesium metal matrix composite

Abstract Magnesium metal matrix composites (Mg MMC’s) developed by different fabrication techniques in last decade have shown high specific strength, stiffness and creep resistance coupled with improvement in wear behavior. Self-infiltration method had been selected among the different techniques in this work to fabricate Mg MMC. AZ91 Mg alloy was used as matrix while B4C and Ti as reinforcements which reacted in situ to form TiC and TiB2. Microstructural investigation and phase analysis were done along with mechanical and wear studies of the developed composite. Microstructural studies showed fairly uniform distribution of TiC and TiB2 reinforcing phase in AZ91 alloy matrix. Some unreacted B4C was also observed. The density and porosity level of developed composite is moderate. Hardness tests done at different cross sections showed large improvement due to addition of hard reinforcements. The wear behavior of AZ91 alloy/TiC, TiB2 composite was investigated through dry sliding test on ball on disc wear test at 5, 10, 15 N loads on both top and bottom surfaces

Investigations on properties of Mg-Al2O3 composites fabricated via stir casting route

Magnesium metal matrix composites are extremely attractive for application of light and strong materials in various industries. In the present work, Magnesium matrix composites reinforced by Al2O3 with different weight percent of particles were synthesized and fabricated by means of Stir casting process. The property of Al2O3 particle content with different weight percent of particles on the mechanical properties of the composites such as density, porosity, hardness and tensile strength were investigated. The microstructures of magnesium metal matrix composites were studied using scanning electron microscope. It showed the uniform distribution of Al2O3 in Mg metal matrix composites and bonded to the composites. The results show that the hardness and the tensile strength of the composites increased with increasing weight fraction of Al2O3 particles.

An overview of the controllable process parameters in mechanical characterization of developed hybrid metal matrix composites and their optimization for advanced engineering applications

The service requirements of industries like aerospace, marine, infrastructure, orthopedic implants and transportation have led to the development of the new age era of advanced engineering materials which have outclassed the conventional materials both in performance and economy. Hence the requirement of advanced engineering materials is increasing day by day with the result new metal matrix composites are developed via stir casting route. The newly developed metal matrix composites have better mechanical properties in comparison to the parent conventional material and they have been successfully employed in advanced engineering and biomedical applications. The optical micrographs obtained through scanning electron microscope and energy dispersive X-ray spectroscopy analysis are used to establish uniform dispersion of the reinforcement in metal matrix and the mechanical properties of the composite are found to be superior than the monolithic alloy. Hybrid Aluminium Metal Matrix Composites are used in aerospace industry because of low weight and economy while hybrid Magnesium Metal Matrix Composites are used in advanced biomedical applications as they possess high strength and biocompatibility. Various optimization techniques like Taguchi, Response surface methodology, Grey Relational Analysis are applied to study optimum combination of various process parameters for better mechanical properties of the novel composite developed via stir casting route. The major controlling factors influencing the mechanical properties of the composite are found to be percentage reinforcement, particle size, stirring speed, preheated mold temperature and ageing time. This paper will provide a brief review on various controllable process parameters and their optimization during mechanical characterization of composites.

Mechanical properties of magnesium-silicon carbide composite fabricated through powder metallurgy route

In this present work, Magnesium metal matrix composites reinforced by silicon carbide were synthesized and fabricated by means of powder metallurgy process. Magnesium powder with 0, 4, 8 & 12 wt% SiC was blended in ball mill for 10 min. Then the cold compaction was done by using compression machine was compressed pressure of 650Mpa at suitable die. The sintering method was performed at 500°and 670 °C and hold time of 30 min using microwave furnace and to achieve better result to sinter the Mg metal matrix composites. The microstructure, density, compressive strength and hardness of the resultant Magnesium-Silicon carbide composites were studied. It was observed that the 12 wt% Silicon carbide reinforcements lead to the improvement in mechanical properties such as high density, high hardness, high compressive strength and high impact strength. Moreover, the outcome exposed that the density, hardness, compressive strength and impact strength of the composite was obviously higher than that of the Cast Magnesium and mechanical properties was improved with higher amount of Silicon carbide reinforcement from 0 to 12 wt%.

Experimental investigation and effects of process parameters on EDM of Al7075/SiC composite reinforced with magnesium particles

Abstract The recent paper presents the experimental investigation on material removal rate (MRR) and electrode wear ratio (EWR) of hybrid metal matrix composite of Aluminium 7075 reinforced with 10% by wt. Silicon carbide particles and nanoparticles of magnesium (Al 7075/10%SiC/Mg). Magnesium metal matrix composites are of significant importance nowadays because of the increasing demand of light weight structural material in aerospace and automotive applications. Stir casting process has been used for fabrication of hybrid metal matrix composite. The effect of process parameters on responses such as MRR and EWR are evaluated during conventional EDM and rotary EDM. The pulse duration, peak current, duty cycle, and tool speed are selected as machining parameters. A comparative analysis of conventional EDM and rotary EDM of hybrid composite has been done. Experimental results indicated that the rotation of the tool enhances the flow of dielectric and effective evacuation of the debris from the gap between the workpiece and tool. The result shows increased MRR and reduced EWR with rotary EDM as compared to conventional EDM. This work seems to be of novelty and the findings can be useful for aerospace and automotive industry.

Wear Behavior on Magnesium Reinforced with Nano Alumina Particulates

The present study explores the wear properties of Mg composites with different amounts of nano- alumina particles (up to 1.4 vol. percent). Tests are carried out on wear device with a constant load of 10N, at sliding speeds range between 1 to 10 m/s compared to EN31 steel disks. Magnesium metal matrix composites reinforced by 1.4 volume percent of alumina particles (nano – sized) possess mechanical properties equivalent or even superior to alike composites of high level micron reinforcement. The outcomes reveals that the introduction of nano powder in various proportions influences the increment of wear performance of magnesium alloy and shows better wear performance at both the speeds by adding 1.4 volume % nano Al2O3 to the pure Mg and other Mg- Al2O3 composites. Due to the presence of Al2O3 as reinforcement for lower and higher sliding speeds, the improvement if found in wear property. The enhancement in wear property of the nano- composites is due to the increased hardness and strength with the nano- alumina particles presence in matrix. Initially there is increase in porosity by the addition of nano alumina to magnesium and later decreased gradually by inceasing the nano alumina percentage. Magnesium nano alumina composites can be considered as an excellent material because of better wear components are of major importance, mainly used in the aerospace and automotive engineering applications.

Multi-walled Carbon Nanotubes Reinforced-Based Magnesium Metal Matrix Composites Prepared by Powder Metallurgy

Nanostructured carbons, for example, carbon nanotubes (CNTs) arise much attraction in the last decades because of its remarkable physical and mechanical properties. The unique physical, chemical and mechanical properties of CNTs make them attractive for biomedical applications. CNTs have been used to modify conventional biomedical materials to enhance mechanical properties, biocompatibility, or to impart other functionalities. One of the metal materials which attract high attention in the biomedical field for orthopaedics application is Magnesium. Recently, many researchers are studying the magnesium reinforced with a different kind of reinforcement. As a lightest metal structure material, magnesium matrix composites show many advantages over monolithic magnesium and magnesium alloys. In this study, Magnesium metal matrix was reinforced by multi-walled carbon nanotubes (MWCNTs) in order to observe the physical and the mechanical properties of the composites. The MWCNTs-Reinforced based magnesium MMC was performed using powder metallurgy process with MWCNTs loading are: 0, 0.1, 0.2, 0.3 and 0.5 %. The temperature of the sintering process was conducted at 600°C by flowing argon gas during the process with the holding time of 2 hours. The experiment result exhibited that the porosity of MMC was increased with the reinforcement by the increasing of the loading MWCNTs observed by metallography and SEM. The mechanical properties showed that the loading of MWCNTs 0.1 % increased the micro-hardness of MMC about 19% compared to pure magnesium, with the peaks at the loading of MWCNTs 0.3 % which increased the mechanical properties about 0.31% at highest hardness value of 46.5 HV.

Experimental investigations of effects of SiC contents and severe plastic deformation on the microstructure and mechanical properties of SiCp/AZ61 magnesium metal matrix composites

The objective of this research is to investigate the effects of equal channel angular pressing (ECAP) plastic deformation processes on the evolution of microstructural distributions and mechanical properties of SiC particles reinforced magnesium metal matrix composites (Mg MMCs). Investigations of the combined effects of the number of ECAP passes and SiC particles weight percentages were considered. The microstructural analysis results demonstrated a uniform distribution of matrix grain sizes and SiC particles (SiCp) segregation along the matrix grain boundaries as the number of ECAP passes increased. As the number of ECAP passes increased the presence and size of secondary phases were reduced at the pure AZ61 magnesium ally and 2 wt% SiCp/AZ61 Mg MMC. In the case of 5 wt% SiCp/AZ61 Mg MMC, the brittle Mg2Si secondary phase was observed and detected throughout the whole ECAP processes. The corresponding mechanical properties experimental investigation results confirmed that the elastic modulus was reduced by 47.98% for pure AZ61, increased by 5.38% for 2 wt% SiCp/AZ61 Mg MMC and increased by 25.9% for 5 wt% SiCp/AZ61 Mg MMC. The ECAP deformed 2 wt% SiCp/AZ61 Mg MMC showed the highest performance of strain hardening rate, strength and ductility.

Multi-objective optimization in WEDM process of graphene – SiC-magnesium composite through hybrid techniques

This paper exhibits a test examination and investigation on the impacts of Wire Electric Discharge Machining (WEDM) parameter on Material removal rate (MRR) and surface roughness (Ra) for the newly developed Magnesium metal matrix composite. Two material parameters (namely reinforcement wt.%, SiC doping %) and three machining parameters (viz. Pulse-On Time (P-ON), Pulse-Off Time (P-OFF), and Wire Feed Rate (WFD)) have been selected to study their effects on the desired output responses (MRR and Ra). The output response variables like MRR and Ra are then analyzed using Taguchi coupled Grey relation analysis. The general belief in any such investigations is that increase in P-ON increases MRR and the same has been revisited through this exhaustive study. Nevertheless, as increased machining time leads to an increase in the manufacturing cost, a trade-off between MRR and Ra, was successfully made by utilizing a Taguchi coupled Grey relation analysis. This gave the best combination of input parameters.

Effects of processing conditions on solidification characteristics and mechanical properties of in situ magnesium metal matrix composites derived from polysilazane precursor

Polymer-derived in situ magnesium metal matrix composites (P-MMMCs) were fabricated by injecting a liquid or cross-linked polysilazane precursor into molten magnesium by a stir-casting method at two different melt temperatures of 700 and 800℃. Microstructural analysis reveals that the composites fabricated at 700℃ exhibit uni-modal grain size distribution having more or less columnar-shaped grain morphology. On the contrary, bi-modal grain size distribution with predominantly dendritic grain morphology occurs in the Mg matrix composites fabricated at 800℃. Such difference in grain morphology can be associated with variation in the availability of heterogeneous nucleation sites, and direction of heat flux during solidification. All of the fabricated composites were investigated for their solidification characteristics, microstructural evolution, micro/nano-hardness and compression properties. This article discusses the correlation between the processing parameters, microstructural evolution and mechanical properties of the as-cast in situ composites fabricated by liquid metallurgical route. Polymer-injection followed by in situ pyrolysis holds the potential of revolutionary processing technologies for producing castings of metal matrix nanocomposites, for example by bubbling the organic liquid with a carrier gas, e.g. nitrogen, into the molten metal by a Bessemer-like process.