Reinforced Aluminum Matrix Composites Research Articles

Dispersion mechanism-induced variations in microstructural and mechanical behavior of CNT-reinforced aluminum nanocomposites

The combination of powder metallurgy and ball milling method has been widely regarded as the most beneficial route for producing multi-walled carbon nanotubes (MWCNTs)-reinforced aluminum matrix composites. In this study, the effects of different milling times (1, 2, 4, and 8 h) on the structural, morphological, and crystallographic properties of MWCNTs-reinforced Al7075 composite powders were characterized by particle size analyzer, Raman spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). After the morphological and structural characterization of the milled powders, the microstructural and mechanical properties of the hot-pressed composites were evaluated using an optical microscope, SEM, density, and Brinell hardness measurements. Considering milled powder characterization, the MWCNTs were gradually distributed and embedded within the matrix as the milling time increased. Milling for 8 h resulted in a minimum level of particle size (11 µm) with shortened and uniformly dispersed CNTs. Brinell hardness of the composite increased from 91 to 237 HB -a ⁓%160 after 8 h of milling. Such a remarkable increment in hardness could be attributed to several concurrent strengthening effects related to dispersion, solution, grain refinement, and Orowan looping mechanisms. However, relative density results revealed that the composite produced by 2 h milled powders exhibited the highest density (%99.96). The observed differences between hardness and density results were ascribed to powders’ deteriorated packing and sintering behavior due to an increment in the hardness of particles and variation in particle size range and morphology, which resulted from following different milling protocols.

Fabrication of continuous carbon-fibers reinforced aluminum matrix composites and coating evolution during heat treatment

The nickel (Ni) was coated onto carbon fibers (CFs) through an electroplating process to enhance the infiltration of aluminum (Al) matrix to fiber. Moreover, these continuous CFs reinforced Al matrix (CF/Al) composites were fabricated via a twin-roll casting method. Here, the effects of rolling speed, pouring temperature and solidification times on the morphologies of CF/Al composites were discussed. The results show that the rolling speed of 4 rad/min provided excellent integrity between reinforcement and matrix. Moreover, solidification times of 60 s offered an effective balance between the heat transfer and infiltration. Furthermore, pouring temperature of 700 °C was advantageous to infiltrate Al matrix into fibers. In addition, the influence of heat-treatment time on coating evolution and property of the materials were discussed through microstructure evolution, phases composition and mechanical property tests. The results confirmed that composites with outstanding mechanical properties were acquired at the temperature of 600 °C for 160 min in a tube furnace. Hence, it is concluded that the twin-roll casting approach has great application prospects in the fabrication of CF/Al composites with high tensile properties.

Microstructure and properties of nano-C and in-situ Al2O3 reinforced aluminum matrix composites processed by high-pressure torsion

ABSTRACT In this study, Al-Si matrix composites reinforced with In situ Al2O3, C nanotubes (CNTs), and graphene nanoplatelets (GNPs) were prepared by ball milling, hot-isostatic pressing (HIP), and subsequent high-pressure torsion (HPT). Microstructures, interfacial bonding, and electrical and mechanical properties of the composites were analysed. In situ Al2O3 particles and whiskers were formed via reaction between Al powder and SiO2 powder. Grains of the composites were significantly refined and reinforcements were well dispersed in the matrix by HPT. A sub-micron equiaxed grain structure with an average grain size of 0.60 μm was obtained. Interface between the CNTs and the matrix was narrow and had no brittle phase. With an increase in the number of HPT cycles, microhardness and electrical conductivity of the composites increased. Strengthening mechanism of the Al matrix composites was mainly fine-grain strengthening. Dislocation accumulation and grain boundary evolution caused by HPT were examined.

The wettability of molten aluminum droplets on the 3C–SiC surface: Molecular dynamics study

AlSiC composites is an irreplaceable material for high temperature semiconductor devices due to its unique performance of high thermal conductivity, low thermal expansion coefficient and bending strength. Understanding of the atomic level interactions between SiC and Al is paramount important. This leads to appropriate control on the transport process at the solid-liquid interface in the preparation of SiC reinforced aluminum matrix composites. To characterize the solid-liquid interaction, the aim is to perform molecular dynamics study on the wetting behavior of molten aluminum droplets on the 3C–SiC surface. The wettability of four crystal surface structure including Si-terminated, C-terminated, rectangular groove, wedge groove was characterized. The corresponding contact angles θ were 113.52°, 80.11°, 108.93° and 132.83° respectively. It was found that the atomic surface terminals and crystal surface morphology play an important role in the wetting behavior of 3C–SiC. High hydrophilic was observed on the C-terminated surface, while the wedge-shaped surface showed high hydrophobic. These theoretical findings demonstrate the effective modeling strategies when using wetting behavior as an interface modeling framework.

Core-shell structure in situ reinforced aluminum matrix composites: Microstructure, mechanical and tribological properties

Aluminum matrix composites with in situ core-shell structure were successfully prepared by powder metallurgy. And the microstructure, mechanical properties and tribological behavior of core-shell structure reinforced aluminum matrix composites were investigated in detail. The results indicate that double core-shells of Al3Ni and NiAl are formed between the Al matrix and Ni3Al reinforcements. The combined effect of Ni3Al reinforcements and the in situ core-shell structure enhance the mechanical and tribological properties of the composites, which is due to the improved strength of the composites and bonding strength between the reinforcements and matrix. Moreover, the serious adhesive wear is significantly alleviated for the composites. Overall, the N15 composite reinforced with 15 vol% Ni3Al exhibits good comprehensive properties, which shows the highest compressive strength of 248 MPa with a strain of 10%, and the optimal friction coefficient and wear rate of 0.74 and 6.45 × 10−5 mm3/(N m), respectively.

Optimization and Tribological Properties of Hybridized Palm Kernel Shell Ash and Nano Boron Nitride Reinforced Aluminium Matrix Composites

The tribological properties of hybridized reinforced aluminium matrix composites were optimized using Taguchi and Grey Relational Analysis in conjunction with an L16 orthogonal array. The combination of palm kernel shell ash (PKSA) (0–5 wt. %) along with nano BN reinforcements was taken in interest. Loads and speeds (500, 750, 1000, and 1250 rpm) were employed as control parameters for the experiment. Using a Taber type abrasion machine, the wear samples were made, and the wear experiments were carried out. Speed and load were more important than the percentage of reinforcements in composites when it came to evaluating wear index and loss of volume. With respect to wear index and volume loss, Taguchi‐relational Grey’s analysis identified A3B1C1 (reinforcement = 5 wt. %; load = 500 g; speed = 500 rpm) as the optimal process parameter combination, with a reinforcement of 3 wt. %, load = 500 g, and speed = 500 rpm being the second‐best option. Validation tests have revealed that the anticipated and experiment values at the optimal situations are both within the acceptable range. Performance is influenced more by speed than by load, which is influenced more by the weight percentage of composites, as demonstrated by the application of the Taguchi and Grey Relational Analysis methods.

Configuration Effect and Mechanical Behavior of Particle Reinforced Aluminum Matrix Composites

Configuration Effect and Mechanical Behavior of Particle Reinforced Aluminum Matrix Composites

Effects of Solid-State Interfacial Reaction on the Mechanical Properties of Carbon Nanotubes Reinforced Aluminum Matrix Composites with Heterogeneous Structure

Effects of Solid-State Interfacial Reaction on the Mechanical Properties of Carbon Nanotubes Reinforced Aluminum Matrix Composites with Heterogeneous Structure

Mechanical property analysis of glass particulates reinforced Aluminum matrix composites

Technological advances involve materials with unique qualities that cannot be provided by ordinary metal alloys, ceramics, or polymeric materials. In the present work, an attempt is made to prepare glass particulates reinforced Aluminum Matrix Composites (AMCs). The composite was prepared using a stir casting process with 0 to 12 wt% glass particulates reinforcement with a particle size of 75 µm. The ASTM standard was used to test mechanical properties such as hardness and tensile strength. The results revealed that the Vickers hardness improved with an increase in weight fractions of glass particulates. The tensile strength increases up to 8 wt% of reinforcement, then decreases up to 12 wt% of reinforcement. The porosity level depicted an increasing trend as the volume percentage of reinforcement increase. The microstructure observation implies that the glass particulates were fairly distributed in 8 wt% and 12 wt% while reinforcement particles' clustering was observed in 4 wt% reinforced composites.

Investigation of mechanical characteristics of SiC and flyash particle reinforced aluminium matrix composites

Achieving a good balance of toughness, strength, stiffness, and density was difficult in the past. Metal matrix composites (MMCs) provide better specific strength, modulus, wear resistance, and damping capacity than non-reinforced composites and alloys. Fly ash is a cheap, low-density byproduct of the combustion process in thermal power plants. Composites reinforced with fly ash are expected to become more affordable in applications demanding low structural weight. A liquid Al containing ceramic particles is necessary for a good Al matrix cast composite, and Si is added to promote wettability. This thesis focuses on the efficient utilisation of fly ash, where particles ranging in size from 0.1 to 100 m were stir cast into an aluminium silicon matrix. The behaviour of these cast composites was studied using a scanning electron microscope and a range of mechanical tests. The composite was also subjected to a dry sliding wear test at varied loadsand velocities.

In-situ formation of particle reinforced Aluminium matrix composites by laser powder bed fusion of Fe2O3/AlSi12 powder mixture using laser melting/remelting strategy

In-situ preparation of particle reinforced Al matrix composites (PRAMCs) by laser powder bed fusion (LPBF) is a promising strategy to strengthen Al-based alloys. The laser-driven thermite reaction can be a practical mechanism to in-situ synthesise PRAMCs. However, the introduction of elements oxygen by adding Fe2O3 makes the powder mixture highly sensitive to form porosity and Al2O3 film during LPBF, bringing challenges to prepare dense materials. This work develops an LPBF processing strategy combined with consecutive high-energy laser melting scanning and low-energy laser remelting scanning to prepare dense PRAMCs from Fe2O3/AlSi12 powder mixture. A high relative density (98.2 ± 0.55 %) was successfully obtained by optimising laser melting (Emelting) and remelting energy density (Eremelting) to Emelting = 35 J/mm2 and Eremelting = 5 J/mm2. Results reveal the necessity to increase Emelting to improve metal liquid’s spreading/wetting by breaking up Al2O3 films surrounding molten pools; however, the high-energy laser melting produced much porosity. Low-energy laser remelting could close the resulting internal pores, backfill open gaps and smoothen solidified surfaces. Although with two-times laser scanning, the microstructure still shows fine cellular Si networks with Al grains inside (grain size 370 nm) and in-situ nano-precipitates (Al2O3, Si and Al-Fe(-Si) intermetallics). Finally, the fine microstructure, nano-structured dispersion strengthening and high-level densification strengthen the prepared in-situ PRAMCs, reaching yield strength of 426 ± 4 MPa and tensile strength of 473 ± 6 MPa. Furthermore, the results can provide valuable information to process other powder mixtures with severe porosity/oxide-film formation potential considering the evidenced contribution of laser melting/remelting strategy to densify material and obtain good mechanical properties during LPBF.

Mechanical behaviour of nano ceramic particles reinforced aluminium matrix composites

New propulsion materials are becoming increasingly popular as a result of the significant growth in industrial innovation over the last few years. Using nano-sized reinforcement materials in aluminium metal matrix composites, engineers will be able to satisfy new engineering demands. In the automobile and aircraft industries, as well as in general industry, they're widely employed. A base material's mechanical strength, wear resistance, and fracture toughness can all be improved by mixing with hard ceramic nanoparticles. By adopting Ultrasonic-Cavitation assisted casting technique, an Al6061 alloy composite comprising varied weight percentages of B4C nanoparticles (ranging from zero to eight weight percent) was effectively manufactured. Although the hardness, ultimate tensile strength, and yield strength of the material all augmented significantly, the ultimate strength decreased as the concentration of B4C Nanoparticles increased.

First-principles Study on Interface of Reduced Graphene Oxide Reinforced Aluminum Matrix Composites

First-principles Study on Interface of Reduced Graphene Oxide Reinforced Aluminum Matrix Composites

SiC particle reinforced Al matrix composites brazed on aluminum body for lightweight wear resistant brakes

Aluminum alloys are well known light-weight alloys and very interesting materials to optimize the strength/weight ratio in order to reduce automotive vehicle weight, fuel consumption and CO2 emissions; unfortunately, they are also relatively soft and therefore cannot be used for high wear applications.The aim of this work was to develop an aluminum alloy brake disc with wear-resistant SiC particle reinforced aluminum matrix composites (SiC/Al) joined on to its surface.Different approaches based on brazing or shrink fitting joining technologies were used to join SiC/Al to the aluminum alloy surface.A functional graded structure was built by brazing thin layers of aluminum matrix composites reinforced with progressively higher amount of SiC particles by using a Zn–Al based alloy as joining material. Several samples were prepared by shrink fitting and brazing: 40 mm x 40 mm x 10 mm samples and a 100 mm diameter brake disc with 68% SiC particle reinforced Al matrix surface and aluminum alloy A365 body. Tribological tests demonstrated that an aluminum alloy brake disc with wear-resistant SiC particle reinforced aluminum matrix composites (SiC/Al) brazed on its surface is a promising technical opportunity.

Remarkable improvement of mechanical properties of layered CNTs/Al composites with Cu decorated on CNTs

Interfacial bond and structure as key points significant restrict the mechanical properties of carbon nanotubes (CNTs) reinforced aluminum matrix composites (CNTs/Al composites). In order to further enhance the interfacial bond of CNTs/Al composites, this paper proposed a novel fabrication process of CNTs/Al composites with Cu nanoparticles decorated CNTs, which results in the remarkable improvement of strength and ductility of CNTs/Al composites. The in-depth study results from microstructure of layered CNTs/Al composites show that: Cu nanoparticles can repair CNTs structural defects, and passivate the reaction activity of the defect points, which successfully inhibit producing big Al4C3 phase. On the other hand, Cu nanoparticles as a bridge connecting Al and CNTs, can improve the interface wettability, and produce an “Al-Cu-CNT” interlocking effect. Due to the improvement of the interfacial bond and structure between CNTs and Al matrix, the strengthening and toughening effect of CNTs is effectively exerted in the Al matrix composites. Additionally, this work avoids the traditional mismatch relationship between strength and ductility in CNTs/Al composites.

Improving the mechanical properties of carbon nanotubes reinforced aluminum matrix composites by heterogeneous structural design

A novel aluminum matrix composites with different lengths of CNTs and heterogeneous structural were prepared in this paper. The synergistic effect of reinforcements with different lengths improves the mechanical properties of composites. Meanwhile, the heterogeneous structure design introduced fiber-like reinforcement to enhance the strength and toughness of composite.

Forming Process and Simulation Analysis of Helical Carbon Fiber Reinforced Aluminum Matrix Composite

In order to promote the industrialization of the large deformation technology of carbon fiber composites, this paper studies a new method of forming of helical carbon fiber reinforced aluminum matrix composite. The purpose is to solve the problem of large deformation of carbon fiber with low elongation and metal matrix with high elongation. By introducing carbon fiber with helical space structure into the aluminum matrix, the helical carbon fiber reinforced aluminum matrix composites were prepared and the subsequent drawing deformation was carried out. Here we systematically studied the large plastic deformation behavior of helical carbon fiber reinforced aluminum matrix composite via a combination of numerical simulations and experiments, and analyzed the deformation law and stress of helical carbon fiber in the deformation process. We found that the plastic deformation of the composite causes local stress concentration around the helical carbon fiber, and the helical carbon fiber will move synchronously with the aluminum matrix during the deformation, and receive the pressure from the aluminum matrix. Second, the best process parameters obtained from the simulation, that is, the drawing die angle α = 7°, when five-pass drawing experiments were carried out, the total deformation reached 58%, and the average elongation of a single pass was 18.9%. The experimental show carbon fiber reinforced aluminum matrix composite with helical space structure can achieve large deformation and high strength. The experimental and simulation are in general agreement, which verifies the correctness of the carbon fiber helical structure model.

Effect of reinforcement volume fraction and T6 heat treatment on microstructure, thermal and mechanical properties of mesophase pitch-based carbon fiber reinforced aluminum matrix composites

To meet the requirements of structural and functional integration, machinability and workability of engineering materials, continuous mesophase pitch-based carbon fiber (MPCF) reinforced 2024 aluminum (Al) matrix composites with 20–50 vol % MPCF were fabricated by vacuum hot pressing method. The effects of MPCF volume fraction and T6 heat treatment on microstructure, thermal and mechanical properties of MPCF/2024Al composites were investigated. The results show that the interface of the as-sintered composite was well bonded. After T6 heat treatment, the amorphous layer at the interface changed from continuous to discontinuous and the interfacial bonding was further improved, but there was no interfacial reaction. The increase of MPCF volume fraction was beneficial to improve the thermal conductivity (TC) and elastic modulus (E) of the as-sintered composites, up to 258.3 W/(m⋅K) and 343.5 GPa respectively, while the composites with 30 vol % and 40 vol % MPCF respectively had the highest ultimate tensile strength (UTS) and a coefficient of thermal expansion (CTE) close to zero. After heat treatment, the TC and E were slightly changed, while the CTE was further reduced and UTS was significantly improved. In this work, the heat-treated composite with 30 vol % MPCF had the highest UTS of 499.3 MPa and good thermal properties, and the TC of this composite may be further improved by using MPCFs with higher TC. Therefore, this composite is expected to become a promising engineering material integrating structure and function.

Manufacturing process of short carbon fiber reinforced Al matrix with preformless and their properties

The conventional manufacturing process of fiber-reinforced metal matrix composites via liquid infiltration processes, preform manufacturing using inorganic binders is essential. However, the procedure involves binder sintering, which requires high energy and long operating times. A new fabrication process without preform manufacturing is proposed to fabricate short carbon fiber (SCF)-reinforced aluminum matrix composites using a low-pressure infiltration method. To improve the wettability between fiber and matrix, fibers were plated copper using an electroless plating process. The low-pressure infiltration method with preformless succeeded in manufacturing a composite with a volume fraction of about 30% of carbon fibers.The fiber orientation of the composite material manufactured without preform and the fiber orientation of the composite material manufactured using an inorganic binder was almost the same. The manufactured composites with preformless have high hardness and high thermal conductivity.

Research on the Secondary Forgeability of High Volume Fraction Whisker Reinforced Aluminum Matrix Composites of Original Squeeze Casting

The poor formability of high volume fraction whisker reinforced aluminum matrix composites of original squeeze casting is an important factor restricting its further development and application. Currently, there are no reports on the secondary forgeability of aluminum matrix composites of original squeeze casting, although some papers on its first forgeability are published. The secondary forgeability is very important for most metals. This study aims to investigate the secondary forgeability of aluminum matrix composites. In this study, the secondary upsetting experiments of 20 vol% SiCw + Al18B4O33w/2024Al composites, treated by the original squeeze casting and extrusion, were carried out. The first upsetting deformation is close to the forming limit, the secondary upsetting deformation under the same deformation conditions was carried out to investigate the secondary forgeability. The experimental results show that, unlike aluminum alloys, the 20 vol% SiCw + Al18B4O33w/2024Al composites at the original squeeze casting and extrusion states have no secondary forgeability due to the whisker rotating and breaking during the secondary upsetting. The high volume fraction whisker reinforced aluminum matrix composites of original squeeze casting cannot be formed by the multiple-forging method since the cavities and cracks caused by whisker fracture continue to expand during secondary processing, which leads to further extension of macroscopic cracks.