Particles In Aluminum Matrix Research Articles

Effect of electromagnetic field and mechanical milling in the synthesis of metal matrix Nano composite

Ceramic nanometric SiC particles (n-SiCp) were reinforced in 7075 aluminium matrix to synthesize the metal matrix nano composites (MMNCs). The inclusion as well as uniform distribution of nano particles in aluminium matrix is a great challenge. To accomplish this, a new hybrid stir casting technique was used to fabricate the MMNCs. The uniform distribution of the reinforcement depends on good wettability of reinforcement with the metal matrix. Hence, to improve the wettability, 1 wt % micro Mg particles were mechanically milled with two different additions of n-SiCp with weight fractions 1% and 1.5 % and injected into the matrix melt with the assistance of argon gas. As-casted materials were peak aged for 12 hours at 135º C. Tensile tests, low speed impact test and hardness tests were used to investigate mechanical behaviour and found that composite reinforced with 1% SiC exhibited better mechanical properties. The mechanical properties of nano-composites are characterized by employing optical microscopy, scanning electron microscopy and X-ray diffractometer. This method remarkably facilitated a uniform dispersion of nano-SiC within the aluminium matrix as well as a refinement of grain size.

Production and microstructural investigation of Al-nano TiB2 composite produced by powder metallurgy technique

Automotive and aerospace industries are required to light materials which have high properties. This causes to reduce production cost and fuel consumption. One of these advanced materials that have been attracted at these decades is particulate metal matrix nanocomposites. These materials have a combination of ductile matrix alloy properties and ceramic reinforcement nanoparticles. Powder metallurgy is one of the significant methods to fabricate this kind of materials. In this research, aluminum alloy matrix nanocomposites reinforced with 1.5, 2.5, 3.5, 5, and 10 Vol. % TiB2 nanoparticles were fabricated via powder metallurgy method. Fabrication was performed at two different sintering temperatures, viz. 650 and 680 °C. Optimum amount of reinforcement and sintering temperature was determined by evaluating density and microstructural studies of nanocomposites. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis illustrated that distribution of nano TiB2 particles in aluminum matrix is suitable. Also, density results showed that with increasing the TiB2 volume percent, density of composites increases.

Manufacturing of nanostructured Al/WCp metal- matrix composites by accumulative press bonding

The accumulative press bonding (APB) process used as a novel technique in this study provides an effective alternative method for manufacturing Al/10 vol.% WCp metal matrix composites (MMCs). The results revealed that by increasing the number of APB cycles (a) the uniformity of WC particles in aluminum matrix improved, (b) the porosity of the composite eliminated, (c) the particle free zones decreased. The X-ray diffraction results also showed that nanostructured Al/WCp composite with the average crystallite size of 58.4 nm was successfully achieved by employing 14 cycles of APB technique. The tensile strength of the composites enhanced by increasing the number of APB cycles, and reached to a maximum value of 216 MPa at the end of 14th cycle, which is 2.45 and 1.2 times higher than obtained values for annealed (raw material, 88 MPa) and 14 cycles APB-ed monolithic aluminum (180 MPa), respectively

The Wear Behavior of In-Situ Al–AlN Metal Matrix Composites

Al–AlN composites are synthesized using NH4Cl + CaO powder as a nitrogenation precursor in the melt of pure aluminum. In-situ formation of AlN to varying volume fraction is attempted using different proportion of NH4Cl + CaO precursor into the aluminum melt held at 700 °C. Mechanical properties of synthesized metal matrix composites are evaluated for different volume fraction and distribution of AlN particles in aluminum matrix. Agglomeration of AlN is noticed with increasing precursor addition and synthesis time into the aluminum matrix. Due to heterogeneous distribution of AlN particles in aluminum matrix, marginal changes in hardness are observed. Pin on disc, dry sliding wear of metal matrix composites is carried to study wear behavior of synthesized composites. Composite with good dispersion of AlN particulates has shown higher hardness and wear resistance. Present paper discusses wear behavior of composites with different weight fraction of AlN tested under load and sliding distance as wear parameters. The shearing mechanism of agglomerate due to friction and its correlation with the wear loss is also highlighted in the present paper.

Study on Quantification of Oxide Phases in Ex-situ AlN/Al Metal Matrix Nanocomposites

Al based metal matrix nanocomposite (MMNC) is synthesized by dispersing nanocrystalline aluminium nitride (AlN) particles in Aluminum matrix using ex-situ melt metallurgy method. The entrapment of atmospheric oxygen along with ex-situ particulate has been a long standing issue during fabrication of metal matrix composites. In the present investigation, presence of oxygen has been quantified in synthesized Al-AlN MMNCs with varying AlN content. The high resolution scanning electron microscopy is used to study morphology and distribution of AlN in Al matrix. Energy dispersive spectroscopy analysis is used to quantify in situ oxide phases along with AlN particles in the synthesized MMNCs using thermodynamic mass balance calculations. Present study also attempts to understand the role of in-situ oxide phases on the mechanical properties of MMNCs using microindentation hardness and nanoindentation test.

Poster #S175 THE ERYTHROCYTE MEMBRANE LIPID ABNORMALITIES OBSERVED IN SCHIZOPHRENIA PATIENTS SUPPORT THE OXIDATIVE STRESS HYPOTHESIS IN SCHIZOPHRENIA

Interface between ceramic particulate and matrix is known to control the response of the materials and functionality of the composite. Among numerous physical properties, grain structure of the materials has also played a significant role in defining the behaviour of metal matrix composites. Usually, silicon carbide (SiC) particles show poor interfacial wettability in aluminium melt. Herein, we were successfully synthesized magnesium oxide (MgO) and nanocrystalline magnesium aluminate (MgAl2O4) spinel coated silicon carbide (SiC) core-shell micro-composites through sol-gel technique to improve the wettability of dispersoids. Core-shell structures of submicron size were thoroughly investigated by various characterization techniques. Further, aluminium matrix composites incorporated with pristine SiC, MgO grafted SiC and MgAl2O4 grafted SiC particles were fabricated by stir casting technique, respectively. Additionally, as-cast composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron back scattered diffraction (EBSD), Field emission scanning electron microscopy (FE-SEM) and X-ray energy dispersion spectroscopy (EDX) analysis were conducted for investigating grain size refinement, adequate dispersion, stability and de-agglomeration of encapsulated SiC particles in aluminium matrix. The mechanical as well as thermal cyclic (from − 100 to 400 °C) damping performance of the as-cast and friction stir processed composites were studied, respectively. Finally, the enhanced properties were attributable to reduced agglomeration, stabilization and proper dispersion of the tailored SiC particles Al matrix.

Fabrication of Hybrid Surface Composite through Friction Stir Processing and Its Impression Creep Behaviour

Al-Ni in situ surface composites were fabricated by friction stir processing method. Friction stir processing produced a composite with nickel and NiAl3 as reinforcement particles in aluminium matrix. The particles were fine and were in the submicrometer size range. The separation distance between the particles was very small. Impression creep experiments were conducted on the samples both at friction stir zone and base material zone at various temperatures. Steady state creep rates were estimated, and activation energy for creep was calculated. It is observed that the friction stir zone offered a higher creep resistance compared to the base metal zone. Higher creep resistance is attributed to the dissolution of nickel atoms into aluminium matrix and the presence of fine nickel particles and NiAl3 precipitates. The measured activation energy indicated that the associated creep mechanism is the dislocation creep in the temperature range of 30–150°C, both in friction stir zone and base metal zone. At higher temperatures (150–180°C) the diffusion creep mechanism is suggested.

Fabrication and characterization of Al6063/SiC composites

In this study, three samples of aluminum alloy with 5%, 10% and 15% SiC composites were fabricated using stir casting process. These samples were investigated using scanning electron microscope equipped with energy dispersive X-ray analysis system, X-ray diffraction analysis and differential thermal analysis techniques. Mechanical properties like hardness, ultimate tensile strength and impact strength of these samples were also investigated. The results revealed that a full homogeneous dispersion of SiC particles in aluminum matrix was obtained without addition of any wetting agent. The peak in the X-ray traces corresponds to the presence of aluminum and SiC and the absence of any significant reactive constituents. The differential thermal analysis curve showed an endothermic peak in aluminum matrix between 648 °C and 650 °C with a nil degradation of material. It was concluded from this study that improvement in mechanical properties of three samples has been achieved. Sample 3 with 15% SiC shows a maximum hardness value (Vickers hardness number) of 120, ultimate tensile strength of 190 MPa and impact strength of 18 J.

Accumulative press bonding; a novel manufacturing process of nanostructured metal matrix composites

A new manufacturing process for metal matrix composites has been invented, namely accumulative press bonding (APB). The APB process provided an effective method to produce bulk Al/10vol.% WCp composite using tungsten carbide (WC) powder and AA1050 aluminum sheets as the raw materials. The microstructural evolutions and mechanical properties of the monolithic aluminum and Al/WCp composite during various APB cycles were examined by scanning electron microscopy, X-ray diffractometry, X’pert HighScore software, and tensile test equipment. The results revealed that by increasing the number of APB cycles (a) the uniformity of WC particles in aluminum matrix improved, (b) the porosity of the composite eliminated, (c) the particle free zones decreased and (d) the cluster characteristics improved. Hence, the final Al/WCp composite processed by 14 APB cycles showed a uniform distribution of WCp throughout the aluminum matrix, strong bonding between particles and matrix, and a microstructure without any porosity and undesirable phases. The X-ray diffraction results also showed that nanostructured Al/WCp composite with the average crystallite size of 58.4nm was successfully achieved by employing 14 cycles of APB technique. The tensile strength of the composites enhanced by increasing the number of APB cycles, and reached to a maximum value of 216MPa at the end of 14th cycle, which is 2.45 and 1.2 times higher than obtained values for annealed (raw material, 88MPa) and 14 cycles APBed monolithic aluminum (180MPa), respectively. Though the elongation of Al/WCp composite lessened during the initial cycles of APB process, it increased at the final cycles of the mentioned process by 78%. Role of WC particles, uniformity of reinforcement, porosity, bonding quality of the reinforcement and matrix, grain refinement, and strain hardening were considered as the strengthening mechanisms in the manufactured composites.

Effect of dual reinforced ceramic particles on high temperature tribological properties of aluminum composites

Abstract The nature and distribution of hard ceramic particles in composite materials influences the properties to greater extent. In the present work, the role of hard ceramic reinforced particles on the tribological behaviour of aluminum metal matrix composites consisting of single (SRP) and dual reinforced particles (DRP) is studied at different temperatures. Zircon sand and silicon carbide particles of size 20–32 μm were used as reinforcement in commercial grade LM13 piston alloy. Composites of dual reinforced particles in aluminum matrix (DRP-AMCs) were developed by mixing 15 wt% reinforced particles by two step stir casting technique. The wear behaviour of DRP-AMCs and SRP-AMCs (single reinforced particles aluminum matrix composite) was investigated using a pin-on-disc method at high temperatures under dry sliding condition. The microstructural examination of developed composites shows globular and finely distributed eutectic silicon in the vicinity of the reinforced particles. Metallographic investigation revealed that the wear zone of the SRP composite consisted of a hardened layer, which is responsible for high wear loss observed in the SRP composite. The results further indicate a transition in the wear mode that occurs after 150 °C for all composites. Study reveals that the dual reinforcement of particles enhances the wear resistance as compared to single reinforced particles if mixed in a definite ratio. A combination of 3% zircon sand and 12% silicon carbide particle reinforced composite exhibits better wear resistance as compared to other combinations at all the temperatures for low and high loads both.

Fabrication and study on mechanical properties and fracture behavior of nanometric Al2O3 particle-reinforced A356 composites focusing on the parameters of vortex method

In the present study, a novel approach was used focusing on nanoparticle distribution in aluminum matrix. To manufacture A356/1.5vol.% nano-Al2O3 reinforced composite, nano-Al2O3 particles were separately milled with aluminum and copper powders and incorporated into A356 alloy via stir casting method. The effects of adding different mixed powders to the matrix and parameters of stirring process on the mechanical properties of the composites were investigated by hardness and tensile tests. Based on the results, it was revealed that the presence of nano-Al2O3 particles in aluminum matrix led to a significant improvement in the mechanical properties of the composites compared with those of the aluminum alloy. This enhancement in mechanical properties can be attributed to the effect of nanoparticles on grain refinement and strengthening of the aluminum matrix. Also, an increase in stirring time led to a decrease in mechanical properties of the composites. These variations in mechanical properties can be attributed to the variation of porosity content versus stirring time. The microstructural characterization of the composites showed the uniform distribution of nanoparticles and grain refinement of matrix. Studies on fracture surfaces revealed that the failure of matrix was the basic mechanism of fracture in this composite.

Fabrication of Al/Ni/Cu composite by accumulative roll bonding and electroplating processes and investigation of its microstructure and mechanical properties

Al–Ni–Cu composite was produced using accumulative roll bonding (ARB) and electroplating processes. Nickel was electroplated on copper substrate for a certain time and voltage. In this study, the microstructural evolution and mechanical properties of the Al–Ni–Cu composite during various ARB cycles were studied by optical and scanning electron microscopes, microhardness, tensile and bending tests. It was observed that at first, nickel layers and then copper layers, were necked, fractured and distributed in aluminum matrix as accumulative roll bonding cycles were increased. Finally, after 11 cycles of ARB process, a completely uniform composite was produced with a homogeneous distribution of copper and nickel particles in aluminum matrix. The results showed that by increasing the number of ARB cycles, the bending strength of produced composite was increased. Also, it was found that when the number of cycles was increased, not only elongation was increased but also the tensile strength of the composite was improved. Microhardness for different elements in different cycles was also evaluated. Finally, fracture surfaces of samples were studied, using scanning electron microscopy (SEM), to reveal the failure mechanism.

Experimental investigations and comparative analysis of friction stir welded AA7075 alloy with and without copper as external alloying element in different forms

Friction stir welding (FSW) experiments were conducted on AA7075 alloys under optimised conditions with copper as external alloy on the faying sides of the base material in thin strip and spray coating form. The idea behind the experimentation is to determine the influence of the formed inter metallic compound (IMC) in enhancing the weld strength, by providing uniform frictional heat input to the top and bottom sides of the plates. Test results of mechanical and metallurgical properties indicate that the interaction of AA7075 alloy with copper, in coating form, enhances the bond strength by formation of Al2Cu and Al4Cu9 IMCs. Lack of metallurgical bond strength due to reduced material flow, caused by the difference in the developed friction heat between the top and bottom sides of the weld in conventional weldments, is considerably reduced by copper coating. High thermal conductivity of the copper in coating form has reduced the temperature gradient and maintained homogenous material flow in the weld zone. Reduction in weld strength is observed in copper strip inserted weldments due to interruption of the unmelted copper particles in aluminium matrix in the weld zone leading to a weak bond.

Effects of breadfruit seed hull ash on the microstructures and properties of Al–Si–Fe alloy/breadfruit seed hull ash particulate composites

The microstructures and properties of Al–Si–Fe alloy matrix composites reinforced with different weight fractions of breadfruit seed hull (husk) ash particles of size 500nm were investigated. Six (6) different weight fractions of breadfruit seed hull ash particles were added to aluminium alloy matrix using a double stir-casting method. Microstructural analysis shows that with the increase of the reinforcement weight fraction, the matrix grain size decreases. The mechanical properties of the composites are improved over the matrix materials, except for the slightly decrease of the impact energy. Fracture surface examination indicates that there is a good interfacial bonding between the aluminium alloy matrix and the breadfruit seed hull ash particles and that fracture initiation does not occur at the particle-matrix interface. Hence, incorporation of breadfruit seed hull ash particles in aluminium matrix can lead to the production of low cost aluminium composites with improved hardness and strength. These composites can find applications in automotive components where light weight materials are required with good stiffness and strength.

Preparation and investigation of Al–4 wt % B4C nanocomposite powders using mechanical milling

Boron carbide nanoparticles were produced using commercially available boron carbide powder (0·8 μm). Mechanical milling was used to synthesize Al nanostructured powder in a planetary ball-mill under argon atmosphere up to 20 h. The same process was applied for Al–4 wt % B4C nanocomposite powders to explore the role of nanosize reinforcements on mechanical milling stages. Scanning electron microscopy (SEM) analysis as well as apparent density measurements were used to optimize the milling time needed for completion of the mechanical milling process. The results show that the addition of boron carbide particles accelerate the milling process, leading to a faster work hardening rate and fracture of aluminum matrix. FE-SEM images show that distribution of boron carbide particles in aluminum matrix reaches a full homogeneity when steady state takes place. The better distribution of reinforcement throughout the matrix would increase hardness of the powder. To study the compressibility of milled powder, modified heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles. For better distribution of reinforcement throughout the matrix, r, modified heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles.

Comparing the effect of processing temperature on microstructure and mechanical behavior of (ZrSiO 4 or TiB 2)/aluminum composites

Recently, a large number of metal matrix composites have been developed for high-performance applications. The first requirement for superior performance of a composite material is the homogeneous distribution of the reinforcing phase. In particulate-reinforced composites, any agglomeration of reinforcement particles deteriorates the mechanical properties of composite. Stir casting route has been used to achieve homogeneity of particle distribution throughout the matrix. In present study, ZrSiO 4 and TiB 2 particles were incorporated in A356.1 alloy. The size of ZrSiO 4 and TiB 2 particles was 1 μm. Reinforcement particles were added to melted aluminum at different temperatures above pure aluminum melting point (750, 850, 950 °C). The volume fraction of reinforcement particles was 5%. After addition of reinforcement, stirring was continued for 12 min for better distribution and better solidification conditions. The microstructure and mechanical behavior of prepared composites were studied. Scanning electron microscopy and X-ray diffraction were used to investigate dispersion of reinforcement particles in aluminum matrix and chemical composition of composites. Hardness and tensile tests were carried out to test mechanical properties. The results of these experiments show that the mechanical properties and microstructure of composites were changed by increasing temperature; also the best condition of ZrSiO 4 case was 750 °C but 850 °C for TiB 2.

Structure and Properties of PM Composite Materials Based on EN AW-AlCu4Mg1(A) Aluminium Alloy Reinforced with the Ti(C,N) Particles

Investigations of composite materials based on EN AW-Al Cu4Mg1(A) aluminum alloy reinforced with the Ti(C,N) particles with various weight ratios of 5, 10 and 15% are presented. The metallographic examinations of composite materials show banding of the reinforcing particles in aluminum matrix after extrusion process. Structure oriented in parallel with extrusion direction is observed in composites materials. Portion of reinforcement particles Ti(C,N) has influence on the mechanical properties of composite materials. The increase of hardness, abrasive wear and decrease of compression strength, tensile strength is observed with the portion growth of reinforcement particles.

Study of Embedded Lead-Tin Nanoparticles in Aluminum Matrix

Nanoembedded lead-tin alloys in aluminum matrix were synthesized by rapid solidification processing. These melt-spun aluminum alloys were then investigated using XRD, EDX and TEM. The XRD study reveals that the melt-spun samples contain elemental aluminum, lead and tin. The TEM analysis shows that embedded particles in aluminium matrix have a distinct two-phase contrast of lead and tin. The lead and tin in these nanoalloys exhibit an orientation relationship with the matrix aluminum and with each other. DSC studies were conducted to reveal the melting and solidification characteristics of these embedded nanoalloys. DSC thermograms exhibit features of multiple solidification exotherms on thermal cycling, which can be attributed to sequential melting and solidification of lead and tin in the respective alloys.

Quantifying Uncertainties in the Thermo-Mechanical Properties of Particulate Reinforced Composites

Recently, there has been a growing interest in the use of particulate reinforced composites in a wide variety of applications. Particle reinforced composites are candidate materials for structures where shock or impact loading is expected. The ICAN (Integrated Composites Analyzer) computer code developed at NASA-Glenn Research Center has been modified to include micromechanics equations for particle reinforced composites. In this work, the simplified micromechanics of particulate reinforced composites and a fast probability integration (FPI) technique have been used to obtain the probabilistic composite behavior of a Al/Si Cp (silicon carbide particles in aluminum matrix) composite. The probability density functions for composite moduli, thermal expansion coefficient and thermal conductivities along with their sensitivity factors are computed. The effect of different assumed distributions in constituent properties and the effect of reducing scatter in input random variable on a select composite property-namely the thermal expansion coefficient are also evaluated. The variations in the constituent properties that directly effect these composite properties are accounted for by assumed probabilistic distributions. The results show that the present technique provides valuable information about the scatter in composite properties and sensitivity factors, which are useful to test or design engineers.

Microstructure and wear characteristics of si particulate reinforced al matrix composites

In order to obtain a homogeneous distribution of fine Si particles in aluminium matrix and thus to improve the adaptability of Al-Si alloy for aerospace and automobile applications, Si particulate reinforced aluminium matrix composites have been processed by using powder metallurgy method. The Si pariticulates with 20–40 μm size and Al alloy powders were mixed, degassed and extruded at 350°C or 400°C depending on the composition of the matrix alloy. The microstructural characteristics of the composites such as interfacial stability at high temperatures have been investigated by various experimental techniques. Wear properties of the composites were investigated by using a pin-on-disk type wear tester. The results were compared with these obtained from the conventionally cast hypereutectic Al-Si alloys and discussed in terms of the observed microstructural characteristics and physical properties such as hardness and tensile properties.