Reinforced Aluminum Matrix Composites Research Articles

Microstructure and properties of 316 L lattice/Al composites by additive manufacturing and infiltration with different temperature

Interface between lattice reinforcement and matrix played a key factor on properties of the lattice reinforced aluminum matrix composites. However, the effect of interface composed of intermetallic compounds on the properties of 316 L lattice/Al composites was still unclear. In this study, 316 L lattice reinforced aluminum composite with continuous interface were prepared by combining laser powder bed fusion (LPBF) and vacuum infiltration, and effect of infiltration temperature on interface evolution and properties of the composite was investigated. Results indicated that a continuous dual-phase interfacial layer consisting of hard intermetallic compounds η-Fe2Al5 and θ-FeAl3 was formed between the reinforcement and matrix due to diffusion and reaction of iron and aluminum atoms, and the size of needle-type FeAl3 phase in the interfacial zone increased when infiltration temperature was up from 800 °C to 900 °C. It also confirmed that reinforced by 316 L lattice and hard intermetallic compounds layer, the composite showed excellent mechanical and wear resistant properties, with compressive strength of 657 ± 32 MPa and specific wear rate of 0.20 × 10−3 (mm3/N·m) for the sample prepared at 800 °C, which were over 10 times and one fifth of that of the aluminum matrix individually. This study provides a new strategy for developing 316 L lattice/Al composites with excellent properties.

Hybrid additive manufacturing of aluminum matrix composites with improved mechanical properties compared to extruded counterparts

Great difficulties existed in fabricating large components of SiC particles reinforced aluminum matrix composites with excellent mechanical properties using existing manufacturing procedures. This study demonstrated that the challenges can be addressed by developing a hybrid solid-state additive manufacturing method. The influence of the deposition procedures and the post-processing heat treatment on the microstructure and mechanical properties of the SiC particles reinforced 2009 aluminum ally matrix composites (SiCp/2009Al composites) was systematically investigated using advanced technologies such as spherical aberration corrected transmission electron microscope, atom probe tomography, etc. The results showed that the SiCp/2009Al composites produced by the hybrid solid-state additive manufacturing exhibited enhanced tensile properties and improved isotropy in mechanical properties compared to the extruded feedstock of SiCp/2009Al composites. This was attributed to the formation of dense metal with uniformly distributed SiC particles, high-density of Cu–Mg co-clusters, refined grains and SiC particles, low deformation texture, tightly bonded SiCp/2009Al interface, and sound interfacial bonding between deposited layers.

Enhancing strength-ductility synergy of thermally oxidized dual-phase HEA particles reinforced aluminum matrix composites via heterogeneous interface

This work firstly oxidizes single-phase high entropy alloy (HEA) to form FCC and BCC dual-phase structure, and also introduces multi-component nano-oxides on surface to prepare oxidized HEA (OHEA) reinforcements, followed by preparation of OHEA/Al composites by spark plasma sintering. The introduction of O element accelerates interdiffusion between OHEA and Al matrix. FCC phase inside OHEA evolves into soft phase, and BCC matrix phase evolves into hard phase, forming heterogeneous interface in OHEA/Al composites. During tensile process, cracks preferentially initiated in hard phase due to severe stress concentration, and the soft phase effectively retarded crack propagation. Compared with 2024Al matrix, yield strength, tensile strength, and elongation of OHEA/Al composites increased by 35.31%, 57.34%, and 63.33%, respectively, realizing excellent combination of strength and toughness. Grain refinement, thermal mismatch, Orowan, and load transfer strengthenings synergistically improve the performance. The proposed method provides a promising avenue to optimize the properties of composites by pre-oxidizing HEA particles to construct heterogeneous interfacial structure.

Enhancing strength–ductility synergy of AlNp/Al composite by regulating heterostructure of matrix grain and particle distribution

Three heterostructured AlNp/Al composites with different microstructure configurations were fabricated by liquid–solid reaction combined with subsequent thermal-mechanical treatment to obtain a superior strength and ductility combination. The effects of the microstructure configuration including the AlN particle distribution and matrix grain structure on the tensile strength and ductility were studied in detail. The results show that the simultaneous enhancement of tensile strength and ductility can be achieved. The Uniformed-AlNp/Al composite with relatively dispersed particles exhibits a superior ultimate tensile strength of ~387 MPa with an elongation to failure of ~9.1%. It shows an outstanding specific tensile strength and elongation combination compared with other reported particle reinforced aluminum matrix composites. Furthermore, the hetero-deformation induced (HDI) stress has been calculated and is shown to increase significantly in the Uniformed-AlNp/Al composite. It is revealed that the HDI stress plays a crucial role in the significant enhancement of strength and ductility for the AlNp/Al composite.

Investigation of the Effect of High-Frequency Induction Sintering on Phase Structure and Microstructure of SiC Reinforced Aluminum Matrix Composites

In this study, SiC-reinforced aluminum matrix composites were powder metallurgically (PM) prepared and sintered using high-frequency induction system (HFIS). The samples with different ratios of SiC (wt.%10, 20 and 40) added to the aluminum matrix were sintered at 660, 800, and 1000 °C. In addition, Al/SiC composites were compared by sintering with the conventional sintering (CS) method under similar sintering conditions. The heating rate for the sintering process using HFIS was 500 °C/min, while the CS method used a heating rate of 10 °C/min. The effect of the temperature and SiC ratio on the density, hardness, phase structure, and microstructure of composites was investigated. The optimum sintering temperature was determined according to the SiC additive amount. When 10%, 20%, and 40% SiC by weight were added to the aluminum matrix in the sintering process with HFIS, the required sintering temperatures were determined as 660, 800, and 1000 °C, respectively. While new phases were not formed as a result of short-term HFIS sintering, a high-temperature Al4C3 phase was detected in CS sintering. HFIS sintered Al/SiC composite samples were obtained in Al and SiC phases with high density and hardness ranging from 43-118 HV. In the high-temperature sintering process with HFIS, the formation of Al4C3 was prevented and its physical and mechanical properties were improved.

A comparison of the erosive wear performance of particle reinforced aluminum matrix composites

A comparison of the erosive wear performance of particle reinforced aluminum matrix composites

Microstructure and Mechanical Properties of Cu-CoatedCarbon-Nanotubes-Reinforced Aluminum Matrix Composites Fabricated by Ultrasonic-Assisted Casting

Carbon nanotubes (CNTs) are considered ideal nanoscale reinforcement for the development of high-performance metal matrix composites due to their unique structure and excellent mechanical properties. However, CNTs are easy to agglomerate and have poor wettability with the aluminum matrix, resulting in unsatisfactory effects when added to the aluminum melt. In this study, Cu-coated carbon nanotubes (Cu@CNTs)-reinforced aluminum matrix composites were fabricated by high-energy ultrasonic-assisted casting. Moreover, the effects of different Cu@CNTs content on the microstructure and mechanical properties of aluminum matrix composites were explored. Meanwhile, Fluent 19.0 software was used to further explore the function of ultrasonic vibration in the melt. The results demonstrated that the mechanical properties of composite with 1.2 wt% Cu@CNTs are optimal. Compared with the matrix, the composite with 1.2 wt% Cu@CNTs displayed a 39.3% increase in yield strength, 53.5% increase in ultimate tensile strength, and 5.7% increase in elongation. The simulation results showed that the uniform dispersion of Cu@CNTs and grain refinement can be attributed to the acoustic streaming effect and cavitation effect of high-energy ultrasound. The improvement of the properties of the composites can be attributed to the grain refinement and the load-bearing effect of CNTs.

Synthesis and characterization of CeO2 modified graphene oxide with improved wettability

In this paper, CeO2 nanoparticles coated graphene oxide (CeO2@GO) nanocomposites were synthesized by a modified hydrothermal method. The morphology and structure of CeO2@GO nanocomposites were characterized systematically. Moreover, the wettability behavior of GO before and after coating CeO2 nanoparticles was investigated. It was found that the CeO2 nanoparticles with an average diameter of ~10 nm were successfully loaded on the GO surface. TEM investigations showed that the CeO2 nanoparticles loaded on the GO surface were dominated by an octahedral shape, and the main exposed surfaces of CeO2 nanoparticles were {111} facets. This was because the closed-packed plane CeO2 {111} had the lowest surface energy. After loading CeO2 on the GO surface, the contact angle between Al drop and CeO2@GO substrate was reduced from 166° to 70° by calculation, attributing to that the CeO2 coating increased the surface free energy of GO. This work provides a feasible method to prepare the rare earth oxides coated GO nanocomposites and shows potential applications in the field of graphene reinforced aluminum matrix composites (AMCs).

Effect of stress shot peening on the microstructure and residual stress of Al18B4O33 whisker reinforced aluminum matrix composite

This work systematically studied the effects of stress shot peening (SSP) on the microstructure, residual stress and hardness of the ultrafine-grained Al18B4O33 whisker reinforced Al-Mg-Si matrix composite (Al18B4O33w/Al-Mg-Si) by the modified Warren-Averbach method, X-ray diffraction stress equipment, transmission electron microscopy and hardness tester. The results showed that conventional shot peening generated a gradient deformation layer of the Al18B4O33w/Al-Mg-Si with ultrafine grains (200–400 nm) near the surface layer. By contrast with conventional SP, SSP effectively induced superior microstructures at the deformed zone with finer crystalline size and more dislocations. In parallel, SSP effectively enhanced the compressive residual stress (CRS) distribution with a higher magnitude of surface CRS (−83 MPa) and maximum CRS (−152 MPa) value and deeper affected depth along the loading direction. The fragmentized whisker during SSP acted as the pinning role on the dislocation movements, which was beneficial for grain refinement and CRS improvement. It is concluded that SSP technique can be regarded as an effective process of improving the surface properties of ultrafine-grained Al18B4O33w/Al composite.

Tensile mechanical behavior and failure mechanism of 2.5D woven fabric reinforced aluminum matrix composites involving residual stress

The tensile behavior of two and a half-dimensional (2.5D) woven fabric reinforced Al matrix composites involving residual stress was investigated experimentally and numerically. The residual stress and subsequent tensile behavior of the composites were predicted by multiscale finite element modeling. And the correctness of numerical simulation is verified by residual stress, tensile curve, surface strain diagram and fracture morphology. The results show that the inhomogeneous residual stress leads to the damage of the matrix and interface in the interweaving area of yarns. During the tensile process, the surface strain exhibits an obvious periodic distribution characteristic, which is related to the arrangement of yarns. With the increase of tensile strain, local matrix and interface damage accumulate and expand leading to the weft yarn cracking, matrix failure and interface debonding successively. The abrupt fracture of the composite can be attributed to the axial fracture of warp yarn, which exhibits obvious fiber fracture and pull-out characteristic.

Joining high volume fraction SiC particle reinforced aluminum matrix composites using Bi2O3-B2O3-ZnO-BaO-Na2O glass

This paper designs a bismuthate glass 58Bi2O3-25B2O3-13ZnO-2BaO-2Na2O in mol%(BBZ) and uses it to join 65 % volume fraction SiC particle reinforced aluminum matrix composites (65 vol%SiCp/ZL102) in an atmospheric environment. The thermal properties of BBZ glass were studied, and the effect of the brazing process on the mechanical properties of the joint was explored. The results show that the glass transition temperature of the glass is 344.6 °C, and the two crystallization temperatures are 464.7 °C and 544.3 °C. The oxidation of the parent material can improve the mechanical properties of the joint. The increase in welding temperature and the extension of holding time make the mechanical properties of the joint first increase and then decrease. When brazing at 490 °C for 30 min, the pre-oxidized composite material was brazed, the joint was defect-free, and the shear strength of the joint was 19.4 MPa. The analysis of the shear fracture showed that the fracture mainly occurred in the glass brazing material, which is a brittle fracture.

Damping and mechanical properties of SiC particles reinforced aluminium matrix composites prepared by colloidal dispersion and suction filtration method

In order to uniformly distribute SiCp in the aluminium matrix and prepare SiCp/Al composites with high mechanical and damping properties, a preparation method of colloidal dispersion and suction filtration was developed. It was observed from the microstructure of the composites that the SiCp/Al composites prepared by colloidal dispersion and suction filtration method had good interfacial structures, and the interfacial reaction between SiCp and aluminium matrix was effectively inhibited. Tensile mechanical properties at room temperature and damping properties in the temperature range of 25 °C to 300 °C were tested for the SiCp/Al composites with volume fractions of 5% to 10%. The results showed that SiCp/Al composites have excellent mechanical and damping properties when the volume fraction of SiCp was 7%. This is because SiCp were uniformly distributed in the aluminium matrix, and formed a good interfacial bond with the aluminium matrix, which benefitted both the interfacial slip loss and the strengthening effect of SiCp.

Agglomerating behavior of in-situ TiB2 particles and strength-ductility synergetic improvement of in-situ TiB2p/7075Al composites through ultrasound vibration

Agglomerates of in-situ particles are the key detrimental defects in particulate reinforced aluminum matrix composites (PRAMCs) by acting as Achilles' heel leading to the premature failure of the materials. Effective methods to disperse/eliminate these agglomerates rely on in-depth understanding of the agglomeration mechanism of the in-situ particles. In this work, the agglomerating behavior of TiB2 particles in Al-Ti-B system was investigated through the thermit reactions between mixed fluorides and molten aluminum. The results indicate that the morphological patterns of TiB2 agglomerates are inherited from the preformed Al3Ti intermedium. The formation of flocculent, shell and flaky TiB2 agglomerates are the results of the diffusing boron atoms continuously reacting with Al3Ti. The in-situ Al-TiB2 was used as a precursor to prepare TiB2p/7075 Al composites. In particular, ultrasound vibration treatment was applied to explore if a locally forced oscillation can deagglomerate the TiB2 agglomerates. Microstructural observations strongly support such speculation. Thanks to the deagglomeration and dispersion of TiB2 particles, both the strength and ductility of the PRAMC have been improved drastically. The fracture surface of the composites was transformed from particle debonding to the dominance of ductile fracture.

Phase stability and microstructural properties of high entropy alloy reinforced aluminium matrix composites consolidated via spark plasma sintering

Spark plasma sintering (SPS) technique was employed in the consolidation of Cr20Mn20Ni20Cu20Nb10Co10 high entropy alloy (HEA) reinforced aluminium matrix composites. Phase stability and prediction expressions were used in the determination of the powder combination for the HEA. The microstructural analysis showed that an interdiffusion layer was formed between the aluminium matrix and the HEA particles in the sintered composites. Further investigation of the composites by X-ray diffraction (XRD) showed that in addition to the Al matrix phase present, other new phases (BCC, FCC and other intermetallics) were formed as a result of the reaction between the Al matrix and the atoms precipitated from the added HEA during sintering. The density of the HEA-reinforced Al matrix composites decreases with an increase in the wt.% of HEA from 98.6 % for pure aluminium to 98.1 % for the reinforced alloy with 10 % HEA, while the microhardness increases with an increase in the wt.% of the HEA from 35 HV for pure aluminium to 96.0 HV for the alloy reinforced with 10 % HEA.

Phase composition and microstructure of B4C particles reinforced aluminum matrix composites fabricated via direct laser deposition

Phase composition and microstructure of B4C particles reinforced aluminum matrix composites fabricated via direct laser deposition

In-situ synthesized polymer-derived SiC reinforced aluminum matrix composites

In the current work, in-situ formed polymer-derived SiC reinforced aluminum-based metal matrix composites were synthesized to uniformly distribute ceramic particles in metal matrix with good matrix-reinforcement interface. Polymeric precursor (allyl hydrido polycarbosilane) was cross-linked at 300 °C and the cross-linked precursor was mixed with molten aluminum at 800 °C under nitrogen using stir casting route to obtained composites reinforced with 2 wt%, 4 wt% and 7 wt% of SiC (particle size < 10 µm) distributed uniformly in the synthesized composites. Structural characterization of samples were performed using FTIR, XRD, optical microscopy, FESEM and Raman spectroscopy. The composites demonstrated significant improvements in hardness (∼58%), ultimate tensile strength (∼45%) and compressive strength (∼58%) for 7 wt% in-situ formed SiC in aluminum matrix compared to pure aluminum.

Effects of the graphene content on mechanical properties and corrosion resistance of aluminum matrix composite

Graphene with excellent mechanical and physical properties has shown its great application potential in aluminum matrix composites. In this paper, graphene oxide nanosheets with negative charges were fabricated by the Hummers' method and they are absorbed on the treated aluminum powders with positive charges by electrostatic self-assembly. Then, graphene reinforced aluminum matrix composites (Gr/Al) were prepared by powder metallurgy. The effects of the Gr content on mechanical performance and corrosion resistance were investigated. The results show that Gr is distributed at the boundary and bonds well with aluminum in Gr/Al composite. Mechanical properties of the composite initially increase then decrease with the increase of Gr content. When the Gr content reaches 0.3 wt%, the ultimate tensile strength reaches 110 MPa and the wear coefficient is 0.39. However, the corrosion resistance decreases with increasing the Gr content and the corrosion mechanism is also investigated in details.

Stimulating adequate strengthening effect through alloying regulation for powder metallurgy CNTs reinforced aluminum matrix composites

Carbon nanotubes (CNTs) reinforced aluminum matrix composites (AMCs) have light weight and high specific strength, showing great potentials for making key structural components in aerospace and transportation industries. Aiming to address the bottleneck problem of unsatisfactory strengthening effect caused by the weak intrinsic interface and adverse interface reaction between CNTs and Al matrix, Si alloying element was added into Al-CNTs system via powder metallurgy method in this study. It was found that the introduction of Si element led to an inhibitory effect on Al-CNTs interface reaction. The discontinuous Al/Si/CNTs composite interface formed by the precipitation of Si significantly improved the wettability of Al/CNTs interface and enhanced its interface bonding through the pinning effect of Si particles, effectively promoting the full play of the load-bearing effect of CNTs. Furthermore, Si particles were effectively refined and passivated through appropriate heat treatment, which facilitated its dispersion strengthening and dislocation strengthening effect, and significantly reduced cracks of coarse Si particles. As a result, the synergistic strengthening effect of CNTs and micro-nano Si particles was significantly exerted in AMCs, remarkably improving the performance of Al–Si-CNTs composites.

Research on micro-cutting mechanism of CoCrFeNiAlX high-entropy alloy fiber–reinforced aluminum matrix composites

Research on micro-cutting mechanism of CoCrFeNiAlX high-entropy alloy fiber–reinforced aluminum matrix composites

Re-dissolution behavior of secondary phases and mechanical response of CNT/2024Al composites

Heat treatment is one of the most effective strategies for regulating microstructure and enhancing the mechanical properties of aluminum matrix composites. In this work, the effects of solution treatment on the static recrystallization behavior, characteristics of secondary phases dissolving, and mechanical response of carbon nanotubes reinforced aluminum matrix composites (CNT/2024Al) were systematically investigated using transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM). Since plenty of deformation stored energy in as-extruded composites is consumed, the residual energy is insufficient to induce static recrystallization during solution treatment. Besides, various interfacial phases aggregated around the Al2Cu phases, which reduced the effective contact area between the Al2Cu phases and matrix, and severely hindered the dissolution process of the Al2Cu phases. The yield strength, tensile strength, and elongation of as-solution treated composites were 23.2%, 44.9%, and 23.0% higher than those of as-extruded composites, respectively. The enhanced yield strength is attributed to solid solution strengthening induced by the dissolution of secondary phases, thermal mismatch strengthening, and the strengthening originating from the formation of Al4C3 phases.