Strength and elastic modulus enhancement in Mg-Li-Al matrix composites reinforced by ex situ TiB2 particles via stir casting

A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion.The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail.The TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt.Compared with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation.The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB2.This work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.

Fabrication and characterization of stir casting AA6061-31%B_4C composite

A sophisticated stir casting route to fabricate large scale AA6061-31%B4C composite was developed. Key process parameters were studied, microstructure and mechanical properties of the composite were investigated. The results indicated that vacuum stirring/casting, B4C/Mg feeding and ingots cooling were essential to the successful fabrication of AA6061-31%B4C composite. Chemical erosion examination verified the designed B4 C content; X-ray fluorescence spectrometer（XFS） showed the chemical composition of Mg and Si in the matrix conformed to industry standards; scanning electronic microscope（SEM） and X-ray diffraction（XRD） revealed that B4 C particles were evenly distributed in the composites with well dispersed Mg2Si precipitates. Tensile testing results showed that the AA6061-31%B4C composite had a tensile strength of 340 MPa, improved by 112.5% compared with AA1100-31%B4C composite, which is attributed to the enhanced strength of the matrix alloy.

Influence of B4C and ZrB2 reinforcements on microstructural,mechanical and wear behaviour of AA 2014 aluminium matrix hybrid composites

Considering their affordability and high strength-to-weight ratio,lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry.This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride(ZrB_(2))and Boron Carbide(B4C).The weight percentage(wt%)of ZrB_(2) was varied(0,5,10,and 15),while a constant 5 wt%of B4C was maintained during this fabrication.The as-cast samples have been assessed using an Optical Microscope(OM)and a Scanning Electron Microscope(SEM)with Energy Dispersive Spectroscopy(EDS).The properties such as hardness,tensile strength,and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy.In particular,dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester.As the weight%of ZrB_(2) grew and B4C was incorporated,hybrid composites showed higher hardness,tensile strength,and wear resistance.Notably,the incorporation of a cumulative reinforcement consisting of 15 wt%ZrB_(2) and 5 wt%B4C resulted in a significant 31.86%increase in hardness and a 44.1%increase in tensile strength compared to AA 2014 alloy.In addition,it has been detected that wear resistance of hybrid composite pin(containing 20 wt%cumulative reinforcement)is higher than that of other stir cast wear test pins during the whole range of applied loads.Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites.Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy.Hence,the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.

Introduction to magnesium alloy processing technology and development of low-cost stir casting process for magnesium alloy and its composites

This paper presents the processing of magnesium alloys and its composite through different stir casting technologies.Design and devel-opment of stir casting technology that is suitable for processing of magnesium alloys has been done in this study.The low-cost stir casting processing of magnesium alloy and its composite with flux and without flux has been explained.The magnesium alloy and its composite have been fabricated by both the stir casting process.The micro structural characterization and mechanical properties of the developed composites has been evaluated.The optical emission spectroscopy of the developed alloy and factography of the developed alloy as well as composite was also examined.

Fabrication of AA2024−TiO2 nanocomposites through stir casting process

Given the nonuse of TiO2 nanoparticles as the reinforcement of AA2024 alloy in fabricating composites by ex-situ casting methods,it was decided to process the AA2024−xTiO2(np)(x=0,0.5 and 1 vol.%)nanocomposites by employing the stir casting method.The structural properties of the produced samples were then investigated by optical microscopy and scanning electron microscopy;their mechanical properties were also addressed by hardness and tensile tests.The results showed that adding 1 vol.%TiO2 nanoparticles reduced the grain size and dendrite arm spacing by about 66%and 31%,respectively.Also,hardness,ultimate tensile strength,yield strength,and elongation of AA2024−1vol.%TiO2(np)composite were increased by about 25%,28%,4%and 163%,respectively,as compared to those of the monolithic component.The agglomerations of nanoparticles in the structure of nanocomposites were found to be a factor weakening the strength against the strengthening mechanisms.Some agglomerations of nanoparticles in the matrix were detected on the fractured surfaces of the tension test specimens.

Fabrication and characterization of GNPs and CNTs reinforced Al7075 matrix composites through the stir casting process

This study investigated the effects of adding graphene nanoplates(GNPs)and carbon nanotubes(CNTs)into the Al7075 matrix via the stir casting method on the microstructure and mechanical properties of the fabricated composites.By increasing the volume fraction of rein-forcements,the fraction of porosity increased.The X-ray diffraction results showed that the addition of reinforcements into the Al7075 changed the dominant crystal orientation from(002)to(111).Field emission scanning electron microscopy images also showed the distribution of clustered reinforcements in the matrix.Between the two reinforcements,the addition of CNTs generated a lower fraction of porosities.Through the addition of 0.52vol%GNPs into the matrix,the hardness,ultimate tensile strength and uniform elongation increased by 44%,32%,and 180%,respectively.Meanwhile,the presence of 0.71vol%CNTs in the matrix increased the hardness,tensile strength and uniform elongation by 108%,129%,and 260%,respectively.

Microstructure and mechanical properties of aluminium metal matrix composites with addition of bamboo leaf ash by stir casting method

Al-4.5%Cu alloy was used as a matrix at2%,4%and6%of bamboo leaf ash(BLA)which was extruded from agro waste and was used as reinforcement.The composite which was fabricated by stir casting method possessed superior properties due to an effective bonding between matrix and reinforcement particles.The fabricated composite specimens were subjected to various tests to determine the mechanical properties such as density,porosity,hardness and tensile strength.The results were compared with basic matrix alloy.Furthermore,the OM,SEM with EDAX and XRD analyses were carried out to analyze the dispersion of the reinforced particles in the selected matrix alloy.It was observed that the homogeneous distribution of BLA particles in composites was intragranular in nature.Moreover,it was also observed that BLA particles were well bonded with matrix alloy with clear interface.It was also found that the density decreased with increase in mass fraction of BLA particles and porosity increased with increase in mass fraction of BLA particles.The hardness and tensile strength were increased up to4%of BLA in the composite,with a further increase in BLA content the hardness and tensile strength decreased.

Fabrication characteristics and tensile strength of novel Al2024/SiC/red mud composites processed via stir casting route

The stir casting technique was used to fabricate aluminum2024matrix hybrid composites reinforced with SiC(5%,mass fraction)and red mud(5%-20%,mass fraction)particles.The developed composites were characterized by using scanning electron microscopy(SEM)and electron dispersive spectrum(EDS)techniques.Further,Taguchi’s approach of experimental design was used to examine the tensile strength of the hybrid composites(with minimum number of experiments).It was found that the reinforcing particles were well dispersed and adequately bonded in the hybrid composites.The density and porosity of the hybrid composites were reduced with the increase in reinforcement content.The tensile strength of the composites increased with the increase in the red mud content and the ageing time.The developed model indicated that the red mud content had the highest influence on the tensile strength response followed by the ageing time.Overall,it was found that Al2024/SiC/red mud composites exhibited superior tensile strength(about34%higher)in comparison to the Al2024alloy under optimized conditions.

Microstructure,mechanical response and fractography of AZ91E/Al_(2)O_(3)_(p) nano composite fabricated by semi solid stir casting method

The present study confers to the fabrication and its characterization of magnesium alloy(AZ91E)based nano composites with nano Al_(2)O_(3) particulate reinforcements.A novel Semi Solid stir casting technique was adopted for the fabrication of the composite.An average particle size of 50 nm was used as reinforcement to disperse in matrix.The effects of change in weight fraction of reinforcements on the distribution of particles,particle–matrix interfacial reactions,physical as well as mechanical properties were reported.The SEM and EDS analysis has shown the uniform distribution of particles in the composite along with the presence of elements.The mechanical properties of reinforced and unreinforced composite were evaluated and presented.Fractography of tensile specimens was also discussed.

Prediction of influence of process parameters on tensile strength of AA6061/TiC aluminum matrix composites produced using stir casting

Stir casting was used to produce AA6061/15%TiC （mass fraction） aluminum matrix composites （AMCs）. An empirical relationship was developed to predict the effect of stir casting parameters on the ultimate tensile strength （UTS） of AA6061/TiC AMCs. A central composite rotatable design consisting of four factors and five levels was used to minimize the number of experiments, i.e., castings. The factors considered were stirring speed, stirring time, blade angle and casting temperature. The effect of those factors on the UTS of AA6061/TiC AMCs was derived using the developed empirical relationship and elucidated using microstructural characterization. Each factor significantly influenced the UTS. The variation in the UTS was attributed to porosity content, cluster formation, segregation of TiC particles at the grain boundaries and homogenous distribution in the aluminum matrix.

Microstructure and mechanical properties of rutile-reinforced AA6061 matrix composites produced via stir casting process

A novel process of fabricating aluminium matrix composites(AMCs)with requisite properties by dispersing rutile particles in the aluminum matrix was studied.A novel bi-stage stir casting method was employed to prepare composites,by varying the mass fractions of the rutile particles as 1%,2%,3%and 4%in AA6061 matrix.The density,tensile strength,hardness and microstructures of composites were investigated.Bi-stage stir casting method engendered AMCs with uniform distribution of the reinforced rutile particles in the AA6061 matrix.This was confirmed by the enhancement of the properties of AMCs over the parent base material.Rutile-reinforced AMCs exhibited higher tensile strength and hardness as compared with unreinforced parent material.The properties of the composites were enhanced with the increase in the mass fraction of the rutile particles.However,beyond 3 wt.%of rutile particles,the tensile strength decreased.The hardness and tensile strength of the AMCs reinforced with 3 wt.%of rutile were improved by 36%and 14%respectively in comparison with those of matrix alone.

Optimization of mechanical properties using D-optimal factorial design of experiment: Electromagnetic stir casting process of A357-SiC nanocomposite

Electromagnetic stir casting process of A357-Si C nanocomposite was discussed using the D-optimal design of experiment(DODOE) method. As the main objective, nine random experiments obtained by DX-7 software were performed. By this method, A357-Si C nanocomposites with 0.5, 1.0 and 1.5 wt.% Si C were fabricated at three different frequencies(10, 35 and 60 Hz) in the experimental stage. The microstructural evolution was characterized by scanning electron and optical microscopes, and the mechanical properties were investigated using hardness and roomtemperature uniaxial tensile tests. The results showed that the homogeneous distribution of Si C nanoparticles leads to the microstructure evolution from dendritic to non-dendritic form and a reduction of size by 73.9%. Additionally, based on DODOE, F-values of 44.80 and 179.64 were achieved for yield stress(YS) and ultimate tensile strength(UTS), respectively, implying that the model is significant and the variables(Si C fraction and stirring frequency) were appropriately selected. The optimum values of the Si C fraction and stirring frequency were found to be 1.5 wt.% and 60 Hz, respectively. In this case, YS and UTS for A357-Si C nanocomposites were obtained to be 120 and 188 MPa(57.7% and 57.9 % increase compared with those of the as-cast sample), respectively.

Effects of yttrium addition and aging on mechanical properties of AA2024 fabricated through multi-step stir casting

The effects of yttrium and artificial aging on AA2024 alloy were investigated.The developed samples were further subjected to artificial aging at 190℃for 1-10 h with an interval of 1 h.The metallurgical characterization was done by scanning electron microscope and X-ray diffraction.The mechanical characterization like hardness and tensile strength of the samples was done using computerized Vickers hardness testing machine and universal testing machine.The microstructures revealed that addition of yttrium refined theα(Al)matrix and led to the formation of Al-Cu-Y intermetallic in the shape of Chinese script which strengthened the samples.Compared to the base metal,samples with yttrium addition showed better mechanical properties.The sample reinforced with 0.3 wt.%yttrium showed the highest mechanical properties with the hardness of 66 HV,UTS of 223 MPa,YS of 180 MPa,and elongation of 20.9%.The artificially aged samples showed that the peak hardening of all the samples took place within 5 h of aging at 190℃with Al2 Cu precipitation.Aging changed the intermetallic from Chinese script to the fibrous form.The optimum amount of yttrium addition to AA2024 was found to be 0.3 wt.%.

Effect of reinforcement content on the adhesive wear behavior of Cu10Sn5Ni/Si3N4 composites produced by stir casting

The main objective of this paper was to fabricate CuSnNi alloy and its composites reinforced with various contents of SiNparticles(5wt%, 10wt%, and 15wt%) and to investigate their dry sliding wear behavior using a pin-on-disk tribometer. Microstructural examinations of the specimens revealed a uniform dispersion of SiNparticles in the copper matrix. Wear experiments were performed for all combinations of parameters, such as load(10, 20, and 30 N), sliding distance(500, 1000, and 1500 m), and sliding velocity(1, 2, and 3 m/s), for the alloy and the composites. The results revealed that wear rate increased with increasing load and increasing sliding distance, whereas the wear rate decreased and then increased with increasing sliding velocity. The primary wear mechanism encountered at low loads was mild adhesive wear, whereas that at high loads was severe delamination wear. An oxide layer was formed at low velocities, whereas a combination of shear and plastic deformation occurred at high velocities. The mechanism at short sliding distances was ploughing action of SiNparticles, which act as protrusions; by contrast, at long sliding distances, direct metal–metal contact occurred. Among the investigated samples, the Cu/10wt% SiNcomposite exhibited the best wear resistance at a load of 10 N, a velocity of 2 m/s, and a sliding distance of 500 m.

Optimization of Stirring Parameters for Stir-Cast Magnesium Matrix Composites Using Response Surface Methodology

The response surface methodology is used to study the effect of stirring parameters on the mechanical properties of magnesium matrix composites(MMCs).The composites are manufactured using different stirring speeds(500,600,and 700 r/min),stirring time(10,20,and 30 min),and weight fractions(0,2.5%,5%,and10%)of silicon carbide particles.The experimental results show that 700 r/min and 20 min are the best conditions for obtaining the best mechanical properties.Based on the desirability function methodology,the optimum parameter values for the best mechanical characteristics of produced composites are reached at 696.102 r/min,19.889 min,and9.961%(in weight).

Properties of Dispersion Casting of Y2O3 Particles in Hypo,Hyper and Eutectic Binary Al-Cu Alloys

In the present work,the dispersion casting of Y-2O-3 particles in aluminum-copper alloy was investigated in terms of microstructural changes with respect to Cu contents of 20 （hypo）,33 （eutectic） and 40 （hyper） wt pct by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）.For the fabrication of Al-Cu alloy dispersed Y-2O-3 ceramic particles,stir casting method was employed.In case of Al-20 wt pct Cu alloy （hypoeutectic）,SEM images revealed that primary Al was grown up in the beginning.After that,eutectic phase with well dispersed ceramic particles was formed.In case of eutectic composition,Y-2O-3 particles were uniformly dispersed in the matrix.When the Cu is added into Al up to 40 wt pct （hypereutectic）,primary phase was grown up without any Y-2O-3 ceramic particles in the early stage of solidification.Thereafter, eutectic phase was formed with well dispersed ceramic particles.It can be concluded that Y-2O-3 ceramic particles is mostly dispersed in case of eutectic composition in Al-Cu alloy.

Machine Learning-Based Research on Tensile Strength of SiC-Reinforced Magnesium Matrix Composites via Stir Casting

SiC is the most common reinforcement in magnesium matrix composites,and the tensile strength of SiC-reinforced magnesium matrix composites is closely related to the distribution of SiC.Achieving a uniform distribution of SiC requires fine control over the parameters of SiC and the processing and preparation process.However,due to the numerous adjustable parameters,using traditional experimental methods requires a considerable amount of experimentation to obtain a uniformly distributed composite material.Therefore,this study adopts a machine learning approach to explore the tensile strength of SiC-reinforced magnesium matrix composites in the mechanical stirring casting process.By analyzing the influence of SiC parameters and processing parameters on composite material performance,we have established an effective predictive model.Furthermore,six different machine learning regression models have been developed to predict the tensile strength of SiC-reinforced magnesium matrix composites.Through validation and comparison,our models demonstrate good accuracy and reliability in predicting the tensile strength of the composite material.The research findings indicate that hot extrusion treatment,SiC content,and stirring time have a significant impact on the tensile strength.

Effects of Processing Technologies on Mechanical Properties of SiC Particulate Reinforced Magnesium Matrix Composites

Mg matrix composites with SiC particles ranging from 5vol%-25vol% were prepared using stirring casting method. Die casting, squeezing casting, and extrusion were applied for inhibiting or eliminating the defects such as gas porosity and shrinkage void. Through die casting and squeezing casting, most of the defects in Mg matrix composites could be eliminated, but the mechanical properties were improved limitedly. On the other hand, after hot extrusion, not only most of the defects of as-cast composites ingots were eliminated, but also the mechanical properties were improved markedly. With the addition of SiC, the tensile strength, yield strength and elastic modulus of as extrusion SiCp/AZ61 composites increased remarkably, and the elongation decreased obviously.

Mechanical and wear behaviour of AZ91D magnesium matrix hybrid composite reinforced with boron carbide and graphite

In this experimental study,magnesium(AZ91D)based boron carbide(B4C)and graphite(Gr)particle reinforced hybrid composite materials were manufactured by stir casting.The tribological and mechanical properties of these composite materials were investigated.The results of the tests revealed that the graphite reinforced hybrid composites exhibited a lower wear loss compared to the unreinforced AZ91D alloy and AZ91D–B4C composites.It was found that with an increase in the B4C content,the wear resistance increased monotonically with hardness and ultimate tensile strength decreased.This study revealed that the addition of both a hard reinforcement(e.g.,B4C)and soft reinforcement(e.g.,graphite)significantly improves the wear resistance of magnesium composites.These entire results designate that the hybrid magnesium composites can be considered as an excellent material where high strength,ultimate tensile strength and wear-resistant components are of major importance,primarily in the aerospace and automotive engineering sectors.

Influence of TiB_(2)addition on friction and wear behaviour of Al2024−TiB_(2)ex-situ composites

Present work encapsulated the friction and wear behaviour of aluminium matrix composites reinforced with different mass fractions of titanium diboride(TiB_(2))particles,synthesized by stir casting.A pin on disc tribotester was employed for conducting the dry sliding wear tests of Al2024−TiB_(2)composites.The tests were performed adopting various parameters like load,sliding distance and sliding velocity for investigating the effect of tribological parameters on the prepared composites.Microstructural characterization confirmed uniform dispersion of TiB_(2)particles and good matrix−reinforcement bonding.Results of the experiments revealed that,low friction and wear rates were observed in the developed composites compared to Al2024 alloy,whereas wear rates of both Al2024 alloy and fabricated composites increased with the increase in load,sliding velocity and sliding distance.However,friction coefficient of both Al2024 alloy and fabricated composites reduced with the increase in applied load but rose with the increase in sliding velocity and sliding distance.SEM studies of the worn surfaces and debris depicted that enhancement in wear resistance can be ascribed to finer debris formation.