Ultrasonic Assisted Casting Research Articles

Microstructure, mechanical properties and interfacial features of graphene oxide reinforced 7075 composites fabricated by ultrasonic assisted casting

Graphene oxide reinforced 7075 (GO/7075) composites were successfully prepared via ultrasonic assisted casting. In this study, the microstructure, mechanical properties and interfacial structure of GO/7075 composites with varying GO contents were investigated. The experimental results showed that GO could refine grain size and produce many dislocations at the GO/Al interface, and was well bonded with Al matrix. Meanwhile, a few rod-like Al4C3 phases were observed at the active prism planes of GO in the composite. When the content of GO reached 1.0 wt%, the optimal mechanical properties of GO/7075 composites were obtained. The yield strength and ultimate tensile strength of 1.0 wt% GO/7075 composites were 212.3 MPa and 285.6 MPa, which were 61.8 % and 41.1 % higher than those of 7075 alloy, respectively. The thermal mismatch strengthening and load transfer strengthening were the main strengthening mechanisms. Moreover, in order to control the interfacial reaction between GO and Al matrix, the thermodynamic/kinetic condition and growth mechanism for the formation of Al4C3 were analyzed in details.

Enhanced interfacial bonding and mechanical properties of CeO2-coated graphene oxide reinforced 7075 composites

Severe interfacial reactions and interfacial bonding between graphene and Al matrix have been the main challenges to achieve high performance graphene reinforced aluminum matrix composites (AMCs). In this study, a new interfacial structure design was proposed to address the above challenges by coating CeO2 nanoparticles on the surface of graphene oxide (GO). Then, CeO2-coated GO reinforced 7075 (GO/7075) composites were successfully fabricated via ultrasonic assisted casting. It was found that the coated CeO2 on GO could react with Al matrix to form Al11Ce3 and suppress the formation of interfacial product Al4C3. Additionally, the as-formed Al11Ce3 at the interface served as a bridge to tightly bind the GO and Al, thus resulting in forming a strong interfacial bonding, which was favour to the load transfer. Moreover, when adding 1.5 wt% CeO2-coated GO, the average grain size of the composites reduced from 100.8 μm to 38.5 μm. As a result, the composite reinforced with 1.5 wt% CeO2-coated GO demonstrated enhanced mechanical properties with a yield strength of 263.4 MPa and an ultimate tensile strength of 342.8 MPa, 100.8% and 69.4% higher than those of unreinforced 7075 alloy, respectively. Furthermore, the strengthening mechanisms of CeO2-coated GO/7075 composites were discussed in detail.

Effect of ultrasound treatment on the performance and segregation of Al–Cu alloy with different Cd contents

By applying ultrasonic treatment to ZL205A aluminum alloy melt containing different Cd contents and then using a tensile test, a scanning electron microscope experiment, and a metallographic experiment, the influence of ultrasonic treatment to ZL205A aluminum alloy melt on the properties of aluminum–copper alloy with different Cd contents in the liquid phase high-temperature region was studied. The effect of ultrasonic treatment on the solidification structure of ZL205A aluminum alloy was investigated. The results showed that there was no significant difference in the form of Cd and the solid solution rate of the aluminum alloy with different Cd contents in ultrasonic-assisted casting. However, the effect of ultrasonic waves on the high-temperature liquid phase of the melt of ZL205A aluminum alloy can effectively reduce the porosity defects in the solidification structure of the casting, refine the solidification structure, and make the structure more uniform. The ultrasonic cavitation effect can promote the formation and uniform distribution of Al–3Ti and improve the nucleation rate, and the effect can continue after heat treatment. This can solve the problem that increasing Cd content in ZL205A greatly reduces the toughness of castings while increasing the strength. The sample with a Cd content of 0.20% and with ultrasonic treatment has the highest strength, the average tensile strength is 475.5 MPa, and the yield strength is 381.75 MPa. However, compared with the conventional casting samples with the same Cd content, the decrease in elongation was significantly reduced.

Influence of T6 heat treatment on the microstructure and tribological properties of ADC12-GNPs composites

The graphene nanoplatelets (GNPs) were used as reinforcement to fabricate the ADC12-GNPs composites via ultrasonic-assisted casting, then the composites were adopted T6 heat treatment. The microstructures and wear performance were investigated in detail. The GNPs effectively refined the α-Al grains and form a strong Al-GNPs interfacial structure with the matrix, and the T6 heat treatment further rounded the Si phases and precipitated nanoscale θ′-Al2Cu. With the increase of load, the wear rate increases. And with the increase of sliding velocity, the wear rate shows a tendency of decreasing and then increasing. The wear rate and COF of the ADC12-GNPs/T6 composites showed a maximum reduction of 63.3 % and 39.2 %, respectively, compared to the matrix. The self-lubrication and refinement strengthening effect of GNPs improved the wear resistance, and the interaction between nanoscale θ′-Al2Cu precipitates and dislocations enhanced the tribological properties. Wear morphology and three dimensional profile analysis showed that the surface roughness of the ADC12-GNPs/T6 composite was 2.73 μm, which was 150 % lower than that of the matrix (6.82 μm) when the sliding velocity was 0.28 m/s and the load was 40 N, showing typical abrasive wear characteristics.

Microstructure and mechanical properties of 7075 composites reinforced with TiO2-coated carbon nanotubes

Microstructure and mechanical properties of 7075 aluminum matrix composites (AMCs) reinforced with TiO2-coated carbon nanotubes (TiO2@CNTs) prepared by high energy ultrasonic assisted casting were investigated. In this paper, a novel method was developed to increase interfacial bonding by coating TiO2 on the surface of CNTs. The results showed that high-energy ultrasound can effectively promote the uniform dispersion of TiO2@CNTs in the melt, and the TiO2@CNTs can refine the α-Al phase. The optimal addition of TiO2@CNTs was 0.9wt.%, and the optimal ultrasonic time was 10 min. The yield strength, ultimate tensile strength, and microhardness of the as-cast composites prepared under the optimal parameters were 201.22 MPa, 261.79 MPa, and 126.02 HV, respectively, which increased by 40.9%, 32%, and 32.2% compared with those of the matrix, respectively. The semi-coherent interface was formed at the TiO2/α-Al interface and well-bonded interfaces between the CNTs and the matrix were formed. The fine grain strengthening, thermal mismatch strengthening, Orowan strengthening, and direct bearing strengthening were considered as four strengthening mechanisms that occurred simultaneously, leading to excellent mechanical properties of as-cast 7075-TiO2@CNTs composites.

Aging behavior, microstructure and mechanical properties of graphene nanoplatelets reinforced ADC12 composites fabricated by ultrasonic assisted casting

The graphene nanoplatelets reinforced ADC12 composites (GNPs/ADC12) were successfully fabricated by ultrasonic assisted casting. The aging behavior, microstructure and mechanical properties of GNPs/ADC12 composites were investigated in this study. It was found that during aging treatment, Al 2 Cu precipitates preferentially nucleated at the GNPs/Al interfaces and dislocations induced by GNPs. This was mainly because the dislocations and interfaces could act as preferred nucleation sites for Al 2 Cu precipitates and diffusion channels for Cu element. And, the addition of GNPs could result in the finer grains, more GNPs/Al interfaces and high density dislocations, thus promoting the precipitation process of GNPs/ADC12 composites. Moreover, GNPs could improve the aging strengthening effect of the composites because of the pinning effect of GNPs on grain boundaries. As a result, the yield strength of peak aged GNPs/ADC12 composites was 245.8 MPa, which was 69.9% higher than that of ADC12 alloy. The peak aged composites were mainly strengthened by dislocation strengthening mechanism, which accounted for 62.3% in total strength contributions. • Al 2 Cu precipitates tend to nucleate at the GNPs/Al interfaces and dislocations. • GNPs can promote the precipitation of Al 2 Cu phase. • GNPs can improve the aging strengthening effect of the composites. • The composites are mainly reinforced by the dislocation strengthening mechanism.

Enhancing the wettability and interface bonding in carbon nanotubes reinforced 2A70 alloy by the coating of ZrO2

Novel CNTs modified with ZrO2 nanoparticles (ZrO2@CNTs) were selected as the reinforcement to prepare ZrO2@CNTs/2A70 via high-intensity ultrasonic assisted casting. The microstructure, wettability, interfacial bonding, and mechanical properties of ZrO2@CNTs/2A70 composites were researched. After modifying ZrO2 on the surface of CNTs, the contact angle of CNTs to 2A70 melt reduced from 140.70° to 116.85°. Thermodynamic calculation indicated that the wetting processes of ZrO2 nanoparticles were spontaneous in initial stage, and then required additional energy from external environment. TEM analysis demonstrated that ZrO2 nanoparticles were uniformly distributed on the surface of CNTs, and could lock the CNTs in matrix, enhancing the interfacial bonding of CNTs-Al. The (010)ZrO2//(010)Al, (010)ZrO2//(100)Al, (010)ZrO2//(100)Al can form semi-coherent interface, indicating a good lattice space matching between ZrO2 and Al matrix. The 1.5 wt% ZrO2@CNTs/2A70 composites manifested excellent mechanical properties and the ultimate tensile strength reached 256.2 MPa, which were 21.47 % higher than that of the matrix (210.9 MPa). The improved mechanical properties may be attributed to the efficient load transfer of ZrO2@CNTs.

Microstructure and tribological properties of Al 7075-TiO2@CNTs composites under T6 treatment

The TiO2 nanoparticles-coated CNTs (TiO2@CNTs) were used as reinforcement to fabricate the 7075-TiO2@CNTs composites via ultrasonic-assisted casting, then the composites were adopted T6 treatment. The microstructures and wear performance were investigated in detail. The TiO2@CNTs could promote the refinement of α-Al grains, reducing the average size by 60.7%. With the addition of 1.0 wt% TiO2@CNTs and introduced T6 treatment, the wear rates have maximally decreased by 48.2% and 69.2%, respectively. The self-lubrication and refinement strengthening effect of CNTs improved the wear resistance, and the strong interfacial bonding between nanoscale MgZn2 precipitates and α-Al further enhanced the tribological properties. The effects of vertical load and sliding velocity on tribological morphology of T6 treatment composites were investigated, demonstrating that with the increase of vertical load, the wear rate and micro-crack tendency increased. Meantime, with the increase of sliding velocity, both the wear rate and the surface roughness showed a decreasing and then increasing trend. The main wear regime was abrasive wear combined with slight oxidation at lower velocities, while delamination wear combined with severe oxidation at higher velocities.

Effect of ultrasonic field on the microstructure and mechanical properties of sand-casting AlSi7Mg0.3 alloy

Abstract The injection of ultrasonic wave into a melt during casting can refine grain size, improve grain distribution, and thereby enhance casting performance. The available studies on ultrasonic-assisted casting are mostly about inserting a transducer directly into the melt. Such a method is not suitable for sand casting. Therefore, the study of ultrasonic sand casting by indirectly injecting ultrasonic waves into an aluminum alloy melt through a sand mold was proposed and carried out in this study. The effects of ultrasonic waves of different powers at different solidification stages on the microstructure and mechanical properties of the melt were studied. Compared to conventional sand casting, the samples prepared by ultrasonic sand casting have finer grains and better grain distribution, as well as higher mechanical properties. Moreover, the sample’s performance improves to different levels when the same ultrasonic wave is injected at different periods, when compared to the injection of ultrasonic waves with different powers in the same period.

Design of metal casting mold for ADC 12 aluminium alloy with assistance of 20 kHz ultrasonic vibration

Metal mold casting is widely used in industry because of higher accuracy than sand casting and lower cost than diecasting. Metal mold casting can yield products with complex shapes and adjustable cooling rate. In this work, designing and fabrication of 20 kHz ultrasonic assisted mold casting using 20Cr steel are studied. Some major components such as motor, heater power, melting chamber are selected and calculated. Model for heating and pouring the ADC 12 alloy is designed. Samples with and without ultrasonic vibration are investigated using 3D laser scan.

Microstructure and mechanical properties of ADC12 composites reinforced with graphene nanoplates prepared by ultrasonic assisted casting

Abstract Microstructure and mechanical properties of ADC12 composites reinforced with graphene nanoplates (GNPs) prepared by high-intensity ultrasonic assisted casting were investigated. The results indicated that high-intensity ultrasound can promote the uniform distribution of GNPs in the melt, resulting in refining the α(Al) phase and Si phase. The optimal addition of GNPs was 0.9 wt.%, and the optimal ultrasonic time was 12 min. The tensile strength, the yield strength and the hardness of the composite produced under the optimal parameters were 256.8 MPa, 210.6 MPa and HV 126.0, respectively, which increased by 30.5%, 42.7%, and 34.8% compared with those of the matrix, respectively. After adding the GNPs, the fracture mechanism gradually turned from a brittle fracture to a ductile fracture. The good interface and distribution allowed GNPs to play the role in fine grain strengthening, dislocation strengthening and load transfer strengthening effectively.

Review on properties of aluminium metal matrix composites

Nowadays, the global industries producing mechanical components are moving towards the usage of composites to reduce weight at the same time without compromising with characteristics of the material being used. This new combination of material provides specific desired properties when combined with various reinforcement materials like SiC, B4C, Al2O3, MgO etc., It is widely used in various industries like aerospace, automobile and marine industries. This property specific tailorable metal matrix composite with Al7075 as the base material can be fabricated using various techniques such as stir casting, high end ball milling, ultrasonic assisted casting, powder metallurgy, squeeze casting friction stir casting etc., out of which stir casting method is preferred by many researchers as stir casting method is seen to provide better distribution of reinforcement particles throughout the metal matrix. It is evident from the research of various authors that when the base material Al7075 is reinforced with the above-mentioned ceramic, it is found that there is a decrease in density and increase in hardness, compressive strength and wear resistance. Here, both physical and mechanical behaviour of aluminium reinforced composites with the effect of the particle size changes, effects after reinforcement and other processing and fabrication methods have been discussed.

Ultrasonication Assisted Fabrication of Aluminum and Magnesium Matrix Nanocomposites - A Review

Recent researches in the domain of casting confirmed that the mechanical properties of aluminum and magnesium based nanocomposites can be appreciably enhanced when ultrasonic cavitation assisted solidification processing is used. Ultrasonic cavitation assisted solidification processing is used for the manufacturing of aluminum and magnesium alloy based metal matrix nanocomposites reinforced with nanoceramic particles. In this solidification processing, formation of clusters have been minimized and the nanoreinforcements were distributed uniformly in aluminum and magnesium matrix nanocomposites. The ultrasonic assisted casting approach will manage the grain dimensions via minimizing agglomeration of nanoparticles in metal matrices. This paper opinions the properties and morphology of aluminum and magnesium based metal matrix nanocomposites fabricated through ultrasonic assisted casting process.

Optimizing Ultrasonic Power on Fabricating Aluminum Nanocomposites Reinforced with Boron Carbide Nanoparticles

In this work, aluminum (Al) alloy reinforced with boron carbide (B4C) nanoparticles were fabricated using ultrasonic assisted casting process. To investigate the effect of ultrasonic power on processing the metal matrix nanocomposites (MMNCs), the MMNC samples were processed with 1.0 kW, 1.5 kW and 2.0 kW of ultrasonic power. The results indicate that the ultrasonic power play a significant role in dispersing the B4C nanoparticles uniformly in Al melt and it also affects the mechanical properties of the fabricated MMNCs. From microstructural analysis it was observed that the MMNC sample processed with 2.0 kW ultrasonic powers possessed the good dispersion of B4C in the Al melt which is the prime criteria for the good mechanical properties.

Investigation of tribological properties of Al-Mg-Si/SiCp nanocomposites prepared by ultrasonic assisted casting method

In the present study, wear properties on 0, 0.5, 1.0 and 1.5 vol% nano-SiCp reinforced Al-Mg-Si alloy metal matrix nanocomposites (MMNCs) fabricated by ultrasonic assisted casting method. The pin on disc apparatus was used for wear testing. Dry sliding wear behavior of nanocomposites were studied by changing the normal load, sliding distance, sliding velocity, and volume fraction of nano-SiCp. The results showed that the wear rates of MMNCs were drastically lower than the unreinforced alloy and the rate of wear decreases as the reinforcement content in the metal matrix increases. The MMNC containing 1.5 vol% nano-SiCp yielded lowest wear rate. It was also observed that the increase in applied load, sliding velocity and sliding distance increases the wear rate of both nanocomposites and monolithic alloy. The average friction co-efficient decreases gradually, with increase in normal load as well as nano-SiCp content. From the scanning electron microscopic images, it was observed that the worn surface had deep long groove in the sliding direction for the monolithic Al alloy, whereas the worn surfaces of MMNCs possessed narrow grooves with almost a flat surface.

Effects of TiC0.5N0.5 nanoparticles on the microstructure, mechanical and thermal properties of TiC0.5N0.5/Al-Cu nanocomposites

In this work, TiC0.5N0.5/Al-Cu nanocomposites with high mechanical and thermal performance were successfully synthesized via ultrasonic assisted casting route. The effects of TiC0.5N0.5 nanoparticle on the microstructure, mechanical and thermal properties of nanocomposites were systematically investigated from micro to nano scale. The microstructural analysis reveals that the TiCN nanoparticles in the matrix mainly exhibit two distribution patterns, i.e. intergranular and intragranular distribution. The experimental results show that the increased addition level can lead to the more refined and homogeneous microstructure and enhanced mechanical and thermal properties. The effects of ultrasonic treatment (UT) and NP addition on the microstructure evolution were discussed and it was found that the enhanced nucleation under ultrasonication and NP-induced growth restriction were the main reasons for the refinement of primary α-Al dendrite and Al2Cu phase. In addition, the 2 vol.% TiC0.5N0.5/Al-Cu nanocomposite can exhibit the optimum mechanical and thermal properties with its hardness, ultimate tensile strength, yield strength, elongation increased by 30 %, 26 %, 30 % and 46 % and coefficient of thermal expansion (CTE) decreased by 6.2 %, respectively as compared to the matrix alloy.

The effects of β-TCP on mechanical properties, corrosion behavior and biocompatibility of β-TCP/Zn-Mg composites.

Zinc has attracted increasing attention in the field of degradable implant materials due to its suitable degradation rate. To further improve the mechanical properties and biocompatibility of zinc, Zn-1Mg-nvol%β-TCP (n = 0, 1, 3, 5) composites were fabricated for biomedical application by the mechanical stirring combined with ultrasonic assisted casting and hot extrusion technology. The microstructure, mechanical properties and corrosion behavior of these composites were systemically investigated and the composite with the best comprehensive performance were selected for biocompatibility evaluation including L-929 cells cytotoxicity test and SD rat model experiment. Tensile test revealed that Zn-1Mg-1vol%β-TCP composite possessed optimal mechanical properties. The yield strength (YS), ultimate tensile strength (UTS), elongation (σ) and elastic modulus (E) of the as-extruded Zn-1Mg-1vol%β-TCP composite are 250.8 MPa, 330.5 MPa, 11.7% and 125.4 GPa respectively. The immersion tests showed that the corrosion resistance of the composite is slightly decreased with the increase of β-TCP content. In addition, the addition of β-TCP makes the cytocompatibility of the composites better than that of the Zn-1Mg alloy matrix. Various blood biochemical parameters in rat serum samples after implantation showed Zn-1Mg alloy and Zn-1Mg-β-TCP composites has not significant tissue inflammation and showed good biocompatibility.

Development of Al-TiCN nanocomposites via ultrasonic assisted casting route.

This work provides a promising approach to achieve the uniform distribution of TiCN nanoparticles (NPs) in aluminum matrix via a combination of ultrasonic dispersion and fast cooling processing. Microstructure analysis demonstrates that as the cooling rate is increased, the NP distribution in the matrix varies from intergranular to intragranular at micro scale and the NP-matrix interface from incoherent to coherent at nano scale. An analytical model is proposed to unveil the effects of cooling rates on the behavior of NPs at the solidification front. The theoretical analysis reveals that the NP size and cooling rate are the two prominent factors determining the NP distribution during solidification of nanocomposites. The experimental results yield an insight into the understanding of NP-induced microstructural evolution and shed new light on the development of high-performance nanocomposites.

Fabrication of Al2O3/SiC/Al Hybrid Nanocomposites Through Solidification Process for Improved Mechanical Properties

To reduce the cost of nanocomposites and improve the dispersion of nanoparticles, Al2O3np/SiCnp/Al hybrid nanocomposites are fabricated by combining liquid-state blowing and ultrasonic-assisted casting. The average grain size of the matrix decreases to 39 μm in Al2O3np/SiCnp/Al, which shows improvements of approximately 118% and 26% as compared to those of Al2O3np/Al and SiCnp/Al, respectively. X-ray Diffractometer (XRD) results confirm the presence of SiCnp and Al2O3np in hybrid nanocomposites. The dispersed SiCnp and Al2O3np are homogeneously distributed in the matrix and no clusters consisting of SiCnp and Al2O3np exist in the microstructure. Theoretical analyses also verify that there is little possibility for clusters to form in the melt. Good bonding between nanoparticles and Al is demonstrated. Neither cavities nor reaction products exist at the interface. The ductility and the strength of Al2O3np/SiCnp/Al are improved. The improvement in yield strength of Al2O3np/SiCnp/Al, in comparison with that of A356, is about 45%.

Synthesis of Metal Matrix Composites through Stir Casting Process – a Review

AbstractMetal is the one of the important material in engineering materials because of their high strength to weight ratio. However the pure metals cannot be used as engineering materials due to their ductile property. So, to improve their mechanical properties, some of the high strength materials (not metals) were added as reinforcement to improve the mechanical properties of pure metals and the newly developed material is called as metal matrix composites. At present, Aluminium, Copper, Magnesium, Titanium and Iron have been used as matrix materials and materials like TiC, SiC, B4C, WC, Cr3C, TiO2, ZrO2, Gr, MoS2and Si3N4have been used as reinforcements. There are many processing techniques to fabricate metal matrix composites namely stir casting, ultra-sonic assisted casting, compo-casting, rheo casting, powder metallurgy technique, etc,. Among these, stir casting process is the most suitable and economical method to fabricate the metal matrix composites. In this article, an effort has been made to review the work of various researchers to fabricate metal matrix composites through stir casting process.