Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.

Squeeze casting for metal alloys and composites:An overview of influence of process parameters on mechanical properties and microstructure

Squeeze casting is a well-established and reliable process for fabricating high-integrity metallic alloys,bimetals,and composites.The quality and high performance of squeeze cast components are dependent on optimum casting conditions.Inappropriate selection of parameter values may adversely affect the quality of the casting.The squeeze cast components are generally subjected to secondary processing such as heat treatment,extrusion,and other bulk deformation processes to improve the microstructural features and mechanical properties.Heat treatment further refines the grains and reduces porosity,consequently improving tensile strength,and hardness;however,ductility decreases.This paper provides a comprehensive review on studies concerning the influence of processing parameters on porosity,density,percentage elongation,strength,hardness,wear,and fracture of squeeze casting alloys,aiming to provide sufficient information on the squeeze casting process and the effects of processing parameters on product quality.

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.

Preparation,Characterization and Photothermal Study of PVA/Ti_(2)O_(3) Composite Films

In this work,flexible photothermal PVA/Ti_(2)O_(3) composite films with different amount(0 wt%,5 wt%,10 wt%,15 wt%)of Ti_(2)O_(3) particles modified by steric acid were prepared by a simple solution casting method.The microstructures,XRD patterns,FTIR spectra,UV-Vis-NIR spectra thermo-conductivity,thermo-stability and photothermal effects of these composite films were all characterized.These results indicated that Ti_(2)O_(3) particles were well dispersed throughout the polyvinyl alcohol(PVA)matrix in the PVA/Ti_(2)O_(3) composite films.And Ti_(2)O_(3) particles could also effectively improve the photothermal properties of the composite films which exhibited high light absorption and generated a high temperature(about 57.4℃for film with 15 wt%Ti_(2)O_(3) amount)on the surface when it was irradiated by a simulated sunlight source(1 kW/m^(2)).

Microstructure characteristics and thermodynamic properties of A357-SiCp/A357 layered composites prepared by semi-solid vacuum stirring suction casting

A357-SiCp/A357 layered composites were prepared using a semi-solid vacuum stirring suction casting method.The microstructures,mechanical properties,and thermal conductivities of the composites fabricated under different suction casting processes were compared.Additionally,the microstructural evolution characteristics and performance enhancement mechanism of the A357-SiCp/A357 layered composites were discussed.The results demonstrate that suction casting at 610°C with a low solid phase ratio can significantly enhance the material density and reduce the agglomeration of SiCp.The A357-SiC_(p)/A357 interface is clear and straight with good bonding.With an increase in the suction casting temperature,the bending resistance and thermal conductivity of the A357-SiC_(p)/A357 layered composites exhibit a trend of significantly increase at first and then slowly decrease owing to casting defects,interface bonding,and SiCp distribution.Compared with SiCp/A357 composites,the bending strength,deflection,and thermal conductivity of the A357-SiCp/A357 layered composites increase from 257 MPa,1.07 mm,and 155.72 W·(m·K)^(-1) to 298 MPa,2.1 mm,and 169.86 W·(m·K)^(-1),respectively.This study provides a reference for improving the rheological casting of aluminum matrix layered composites.

Interface characteristics and wear resistance of Ni-B_(4)C plated ZTA reinforced high chromium cast iron composite

A chemical composite plating of Ni-B_(4)C was used to prepare the surface-modified zirconia toughened alumina(ZTA)ceramic particles.The ceramic preforms were prepared by the plated ZTA and sodium silicate solution binder,followed by casting infiltration to prepare the ZTA particles reinforced high chromium cast iron(HCCI)composites.The result reveals that a distinct interface layer forms at the ZTA/HCCI interface,which consists of phases of ZrB_(2),FeB,Fe_(2)B,and NaSiO_(4).The interfacial wettability between ZTA and HCCI is improved by the diffusion and reaction of Ni and B_(4)C.The wear test reveals that the Ni-B_(4)C plated ZTA particles can effectively improve the wear resistance of the ZTA/HCCI composite,and the wear rate of the composite is decreased to 11.6%of HCCI.

Microstructures and mechanical properties of TC4/AZ91D bimetal prepared by solid-liquid compound casting combined with Zn/Al composite interlayer

To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid-liquid compound casting,respectively.Al interlayer was prepared on the surface of TC4 alloy by hot dipping,and Zn/Al composite interlayer was prepared by electroplating process.The results suggested that the phases across the interface were Al Ti andα(Al)+Mg_(21)(Al,Zn)_(17)when Zn/Al composite interlayer was used.When Al interlayer was used as interlayer,Al Mg Ti ternary structure and Al_(12)Mg_(17)+δ-Mg eutectic structure were the main phases at the interface.The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer,and the value of the shear strength was increased from 48.5 to 67.4 MPa.Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.

Direct-chill semi-continuous casting process of three-layer composite ingot of 4045/3004/4045 aluminum alloys

Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructure and composition distribution of the composite interface were investigated.The results show that semi-solid layer with a certain thickness forms near the interface due to the effect of cooling plate,which ensures successful implementation of casting the composite ingot.Two different aluminum alloys are well bonded metallurgically.The mechanical properties of composite interface were measured,the tensile and shearing strengths of composite interface are 105 and 88 MPa,respectively,which proves that the composite interface is a kind of metallurgical bonding.

Effect of applied pressure on microstructure and mechanical properties of Mg-Zn-Y quasicrystal-reinforced AZ91D magnesium matrix composites prepared by squeeze casting

The Mg-Zn-Y quasicrystal-reinforced AZ91 D magnesium matrix composites were prepared by squeeze casting process. The effects of applied pressure on microstructure and mechanical properties of the composites were investigated. The results show that squeeze casting process is an effective method to refine the grain. The composites are mainly composed of α-Mg, β-Mg17Al12 and Mg3Zn6Y icosahedral quasicrystal phase（I-phase）. With the increase of applied pressure, the contents of β-Mg17Al12 phase and Mg3Zn6 Y quasicrystal particles increase, further matrix grain refinement occurs and coarse dendritic α-Mg transforms into equiaxed grain structure. The composite exhibits the maximum ultimate tensile strength and elongation of 194.3 MPa and 9.2% respectively when the applied pressure is 100 MPa, and a lot of dimples appear on the tensile fractography. Strengthening mechanisms of quasicrystal-reinforced AZ91 D magnesium matrix composites are chiefly fine-grain strengthening and quasicrystal particles strengthening.

Microstructures and properties of A356-10%SiC particle composite castings at different solidification pressures

A356-based metal matrix composites with 10% SiC particles of 10 rtm were fabricated by stir casting and direct squeeze casting process under applied pressures of 0.1 （gravity）, 25, 50 and 75 MPa. The microstructures and mechanical properties of the as-cast and T6 heat-treated castings were investigated. The results show that as the applied pressures increase, the casting defects as particle-porosity clusters reduce and the incorporation between the particles and matrix can be improved. The tensile strength, hardness, and coefficients of thermal expansion （CTE） increase with the increase of the pressures. Compared with the as-cast composite castings, the tensile strength and hardness of the heat-treated casting are improved whereas CTEs tend to decrease in T6-treated condition. For the gravity cast composites, there are some particle-porosity clusters on the fracture surface, and the clusters are hardly detected on the fracture surface of the samples solidified at the external pressures. Different fracture behaviors are found between the composites solidified at the gravity and imposed pressures.

Effects of temperature on fracture behavior of Al-based in-situ composites reinforced with Mg_2Si and Si particles fabricated by centrifugal casting

An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on fracture behavior of the composite were investigated. The results show that the average fraction of primary Si and Mg2Si particles in the composites is as high as 38%, and ultimate tensile strengths （UTS） of the composites first increase then decrease with the increase of test temperature. Microstructures of broken specimens show that both the particle fracture and the interface debonding affect the fracture behavior of the composites, and the interface debonding becomes the dominant fracture mechanism with increasing test temperature. Comparative results indicate that rich particles in the composites and excellent interface strength play great roles in enhancing tensile property by preventing the movement of dislocations.

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.

Horizontal continuous casting process under electromagnetic field for preparing AA3003/AA4045 clad composite hollow billets

A modified horizontal continuous casting process under the electromagnetic field was proposed for preparing AA3003/ AA4045 clad composite hollow billets. To investigate the effect of electromagnetic field on this process, a comprehensive three-dimensional model was developed. Two cases with and without electromagnetic field were compared using the simulations. When rotating electromagnetic stirring is applied, the flow pattern of fluid melt is greatly modified; the mushy zone becomes much wider, the temperature profile becomes more uniform, and the solid fraction decreases for both the external and internal alloy melt layers. These modifications are beneficial for the formation of a bimetal interface and fine and uniform grain structure of the clad composite hollow billet. Experiments conducted using the same electrical and casting parameters as the simulations verify that under the electromagnetic field the microstructure of the clad composite hollow billet becomes fine and the diffusion of the elements at the interface is promoted.

The Role of Particles in Fatigue Crack Propagation of Aluminum Matrix Composites and Casting Aluminum Alloys

Fatigue crack propagation （FCP） behaviors were studied to understand the role of SiC particles in 10 wt pct SiCp/A2024 composites and Si particles in casting aluminum alloy A356. The results show that a few particles appeared on the fracture surfaces in SiCp/Al composites even at high △K region, which indicates that cracks propagated predominantly within the matrix avoiding SiC particles due to the high strength of the particles and the strong particle/matrix interface. In casting aluminum alloy, Si particle debonding was more prominent.Compared with SiCp/Al composite, the casting aluminum alloy exhibited lower FCP rates, but had a slight steeper slope in the Paris region. Crack deflection and branching were found to be more remarkable in the casting aluminum alloy than that in the SiCp/Al composites, which may be contributed to higher FCP resistance in casting aluminum alloy.

Synthesis and characterization of 356-SiC_p composites by stir casting and compocasting methods

Stir casting is one of the simplest ways of producing aluminum matrix composites.However,it suffers from poor incorporation and distribution of the reinforcement particles in the matrix.These problems become especially significant as the reinforcement size decreases due to greater agglomeration tendency and reduced wettability of the particles with the melt.Development of new methods for addition of very fine particles to metallic melts which would result in more uniform distribution and effective incorporation of the reinforcement particles into the matrix alloy is therefore valuable.In this work,356-5%SiCp(volume fraction) composites,with average SiCp sizes of about 8 and 3 μm,were produced by injection of different forms of the reinforcement particles into fully liquid as well as semisolid slurries of 356 aluminum alloy and the effects of the injected reinforcement form and the casting method on distribution of the reinforcement particles as well as their porosity,hardness and impact strength were investigated.The results reveal that addition of SiC particles in the form of(Al-SiCp)cp composite powder and casting in semisolid state decreases the SiCp particle size,enhances the wettability between the molten matrix alloy and the reinforcements and improves the distribution of the reinforcement particles in the solidified matrix.It also increases the hardness and the impact energy of the composites and decreases their porosity.

Centrifugal casting processes of manufacturing in situ functionally gradient composite materials of Al-19Si-5Mg alloy

Cylindrical components of in situ functionally gradient composite materials of Al-19Si-5Mg alloy were manufactured by centrifugal casting. Microstructure characteristics of the manufactured components were observed and the effects of the used process factors on these characteristics were analyzed. The results of observations shows that, in thickness, the components possess microstructures accumulating lots of Mg2Si particles and a portion of primary silicon particles in the inner layer, a little MgzSi and primary silicon particles in the outer layer, and without any Mg2Si and primary silicon particle in the middle layer. The results of the analysis indicate that the rotation rate of centrifugal casting, mould temperature, and melt pouring temperature have evidently affected the accumulation of the second phase particles. Also, the higher the centrifugal rotation rate, mould temperature, and melt pouring temperature are, the more evident in the inner layer the degree of accumulation of Mg2Si and primary silicon particles is.

Distribution of SiC particles in semisolid electromagnetic-mechanical stir-casting Al-SiC composite

The distribution of SiC particles in Al-SiC composite can greatly influence the mechanical performances of Al-SiC composite. To realize the homogeneous distribution of SiC particles in stir-casting Al-SiC composite, semisolid stir casting of Al-4.25 vol.%SiC composite was conducted using a special electromagneticmechanical stirring equipment made by our team, in which there are three uniformly-distributed blades with a horizontal tilt angle of 25 ° to mechanically raise the SiC particles by creating an upward movement of slurry under electromagnetic stirring. The microstructure of the as-cast Al-SiC composites was observed by Scanning Electron Mcroscopy(SEM). The volume fraction of SiC particles was measured by image analysis using the Quantimet 520 Image Processing and Analysis System. The tensile strength of the Al-4.25 vol.%SiC composites was measured by tensile testing. Results show that the Al-4.25 vol.%SiC composites with the homogeneous distrbutin of SiC particles can be obtained by the electromagnetic-mechanical stirring casting with the speed of 300 and 600 r·min-1 at 620 °C. The differences between the volume fraction of Si C particles at the top of ingot and that at the bottom are both ~0.04 vol.% with the stirring speed of 300 and 600 r·min-1, which are so small that the distribution of SiC particles can be seen as the homogeneous. The tensile strength of the Al matrix is enhanced by 51.2% due to the uniformly distributed SiC particles. The porosity of the composite mainly results from the solidification shrinkage of slurry and it is less than 0.04 vol.%.

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.

Effects of RE,V,Ti and B composite modification on the microstructure and properties of high chromium cast iron containing 3% molybdenum

The effects of RE, V, Ti and B on the microstructure and properties of high chromium cast iron containing 3% molybdenum under as-cast and heat treatment conditions were investigated with the method of comparing experiments. The results show that with the increase of RE content, the primary austenite of high chromium cast iron is obviously refined. The morphology of carbide is changed from netlike and lath to small multiangular isolated blocks or massive blocks, the isolated degree of carbide is improved obviously, and the size is significantly refined. The addition of V and B into high chromium cast iron can refine the microstmcture, reduce coarse columnar crystals and make the carbide smaller and uniform. Through composite modification with RE, V, Ti and B, the hardness, wear resistance and impact toughness of high chromium cast iron are increased conspicuously. After heat treatment, the hardness of high chromium iron is increased significantly, but the toughness and wear resistance do not show great improvement.

Preparation of composite aluminum automobile radiator by inversion casting

The inversion casting technics of producing three ply Al Mn/Al Si composite strap used in automobile radiator was studied. The physical processes of inversion casting, including the flux supporting reacting and volatilizing at high temperature, the melting and solidification when the elements of solid and liquid fresh alloys meet with each other, the mutual diffusion of elements in solid and liquid, the crystallization and forming of metallurgical combination and the following rolling process, were analyzed. At the same time, the composite mechanism of this technique was also discussed. [