Matrix Composite Sheets Research Articles

Microstructure evolution, mechanical properties and strengthening mechanism of titanium matrix composite sheets

The microstructure evolution and mechanical properties of high-Zr containing titanium matrix composite (TMC) sheets with different deformation amounts were systematically studied. The results showed that the degree of αp phase refinement and the content of silicide precipitation of TMC sheets increase with the increase in deformation amount during hot rolling, which is sensitive to the preheating and reheating during rolling. The refined αp phase can impede the effective slip distance of dislocations and the silicide precipitated in the inner α phase can also strengthen αp phase, while the nano-αs phase can strengthen the βt domain. Due to the different hardness values of αp and βt domains, the αp/βt boundaries can induce back stress to βt domain and forward stress to αp, leading to heterogeneous deformation induced strengthening effect. The dislocation motion in αp phase was analyzed by transmission electron microscopy (TEM), which showed that the large deformation causes the dislocations to be tangled and unable to be distinguished. This indicates that dislocation strengthening is an indispensable strengthening mechanism until high-temperature tensile deformation. The ultimate tensile strength (UTS) and yield strength (YS) of the TMC sheets reach 726 MPa and 634 MPa at 650 °C, respectively, while the UTS at room temperature reaches the maximum of 1445 MPa, giving the TMC sheets a great application prospect in aerospace fields. Due to the strengthening of βt domain and αp phase, dislocations are blocked at the αp/βt boundaries. As a result, the failure of TMC sheet can be attributed to cracks distributed at αp/βt boundaries. The cracks around reinforcements also cannot be ignored due to the load transfer from matrix to reinforcements.

Numerical and experimental investigation of formability in incremental sheet forming of particle-reinforced metal matrix composite sheets

Aluminium matrix composites (AMCs) have a high strength-to-weight ratio, high stiffness, and good damage resistance under a wide range of operating conditions, making them a viable alternative to traditional materials in a variety of technical applications. Because of their high strength, composite materials are hard to deform to a desired shape and depth at room temperature. As a result, additional treatments are required to enhance the composite’s ductility at room temperature prior to deformation. In this investigation, as-received 6092Al/silicon carbide particle (SiCp) composite sheets (T6-condition) are heat-treated to O-condition annealing to enhance its ductility in order to assess the formability and fracture behaviour of the Al/SiC particle composite sheets under single point incremental forming (SPIF) using different forming parameters at room temperature. The annealed sheets are heat-treated to T6-condition to enhance the strength and achieve properties equivalent to as-received sheet properties. The results demonstrate that the Al/SiC particle composite sheets with T6 treatment could not be deformed to the specified depth due to low ductility at room temperature. Further treatment, such as O-condition annealing, is required to enhance its ductility to enable successful deformation of the Al/SiCp sheets using SPIF. After SPIF processing, the annealed Al/SiCp composite sheets are heat-treated back to T6. The sheets exhibit properties comparable to the as-received sheets. Al/SiC particle composite sheets with low values of SPIF parameters, i.e. small tool diameter, low step size and feed rate, are able to achieve greater formability and fracture depth with low strain hardening under SPIF processing conditions.

Microstructure and Mechanical Properties of Ultrahigh‐Speed Friction‐Stir‐Welded Joints of In Situ Al3Zr Particle‐Reinforced Aluminum Matrix Composite Sheets

Herein, in situ Al3Zr + 6082Al aluminum matrix composite sheets subjected to ultrahigh‐speed friction stir welding (FSW) at welding and stirring‐head rotation speeds of 200 mm min−1 and 11 000, 13 000, or 15 000 rpm, respectively, are focused on. X‐ray diffraction, electron microscopy, energy‐dispersive spectrometry, microhardness testing, and tensile testing are used to investigate the microstructures and mechanical properties of the welds. The weld nugget zone (NZ) of the high‐speed FSW joint of the Al3Zr + 6082Al matrix composite sheet comprises mainly equiaxed recrystallized grains, the thermomechanically affected zone comprises equiaxed recrystallized grains and elongated plastically deformed grains, and the heat‐affected zone comprises recrystallized grains. Results show that the FSW joint formed at 13 000 rpm and 200 mm min−1 is extremely well formed and has a compact and uniform structure. The microhardness of the 13 000 rpm FSW joint is highest at an NZ hardness and tensile strength of 128.08 HV and 153.7 MPa (87% of that of the base metal), respectively.

Physical simulation of hot rolling of powder metallurgy-based Al/SiC composite by plane strain multi stage compression

The development of lightweight materials like Al/SiC metal matrix composite sheet is a challenge by different manufacturing processes for further application in the automobile and aerospace industries. In the present work, plane strain multistage compression was used to investigate the hot rolling of powder metallurgy-based Al/7vol.%SiC composite. The cuboids of dimension (80 mm × 45 mm × 15 mm) from this composite material were synthesized using a conventional powder metallurgy technique. Then, the plane strain samples were cut from these composite cuboids. After that, plane strain multistage compression tests were performed using a thermo-mechanical simulator, Gleeble-3800. The multistage compression consists of six stages of different strains and all stages were compressed at a constant strain rate (1 s−1) to achieve a final logarithmic strain of 1.5. All the plane strain stages were conducted at four different temperatures (350, 400, 450 and 500 °C). The flow curves obtained from the plane strain experiments show the initial hardening, then steady-state followed by final hardening. A constitutive equation for flow stresses has been developed and it predicts within the error of 2.62–6.18%. Then, the activation energy and dislocation densities are calculated and analyzed. Dislocation density is significantly high for this composite at the end of deformation as compared to the sintered one. After that, hot rolling experiments were conducted to make the Al/7vol.%SiC composite sheets. A comparative microstructural characterization has been examined using the optical image and electron backscatter diffraction. Recrystallized, deformed and sub-structured grains were observed in the hot-rolled sheet. The tensile fracture mechanisms are particle crack, void, growth and facet, whereas the edge crack in the plane strain samples due to particle crack and debonding. This study opens up the possible use of plane strain compression to design the hot rolling process in the industry for Al-metal matrix composites sheets.

The lamella structure of Al-Mg-Si matrix nanocomposites with isotropically high strength

The anisotropy usually appears after the deformation and is difficult to control in Al alloys. The high and isotropic strength was achieved simultaneously by cross accumulative roll bonding processes in this work due to the controlled nanoparticle distributions in different directions. The hierarchical structure with bimodal-sized grain and precipitate sizes was found in the composites, resulting in considerable tensile performance. The ultimate tensile strength and yield strength were ~ 450 MPa and 380-390 MPa after CARB processes, respectively. This work provides new methods for fabricating Al matrix composite sheets with high and isotropic strength.

Aluminum Alloy Matrix Composite Reinforced with Metallic Glasses Particles Using Hot-Roll Bonding

Composite materials (CMs) exhibit high hardness, mechanical strength, and wear resistance, but their processing properties are limited. The most popular reinforcements for composites are carbides, nitrides, and oxides. Amorphous metallic materials are an alternative reinforced component. Metallic glass can provide increased properties due to higher interphase strength between their particles and the metallic matrix when compared with nonmetallic particles. A sheet of metal matrix composite has been processed by roll bonding. The composite consists of an aluminum-based matrix reinforced by particles of Co48Cr15Mo14C15B6Tm2 metallic glasses and a cladding layer of AA5083 alloy. The thickness of the central layer of Al–5% Zn–5% Ca alloy reinforced by metallic glasses particles is 60% of the total thickness of the sheet, and the thickness of the cladding layer is 20% on the both sides. Granules of the CM were processed by mechanical alloying with the subsequent consolidation to the balk sheet by roll bonding in clad sheets at the temperature below class transition temperature of the amorphous component. The reinforcement compound retains the amorphous state after mechanical alloying and hot rolling, which is shown by X-ray and differential thermal analysis. The microstructure after different processing steps is studied by scanning electron microscopy and the mechanical properties of the metal matrix composite sheet at room temperature are studied. Amorphous particles have a size range of 2 to 187 μm and volume fraction of about 10%. The hardness of the composites is 25% higher than the hardness of basic alloy Al–5% Zn–5% Ca. The yield strength of the cladded CM is two times higher than that of metallic alloys of the matrix and cladding.

Aluminum alloy matrix composite reinforced with metallic glasses particles using hot-roll bonding

Composite materials (CM) exhibit high hardness, strength and wear resistance with slightly limited processing properties. The most popular reinforcing components for discretely reinforced composites are carbide, nitride or oxide particles. Amorphous metal materials can be used as an alternative reinforcing component since reinforcement with these particles can ensure improved properties due to higher strength of interfacial bonding between the particles and matrix as compared to traditional reinforcements. A metal matrix composite sheet was obtained based on the Al—5%Zn—5%Ca alloy reinforced by particles of Co 48 Cr 15 Mo 14 C 15 B 6 Tm 2 amorphous metallic glasses with the AA5083 cladding layer. The central layer thickness of the Al—5%Zn—5%Ca alloy reinforced by metallic glass particles covered 60 % of the sheet thickness, and the cladding layer covered 40 % in total. Composite material granules were obtained by mechanical alloying with their subsequent consolidation by hot-roll bonding in the cladding shell at the temperature below the amorphous component devitrification temperature. X-ray and differential thermal analysis showed that metallic glasses retain their amorphous structure after processing in the planetary mill and further consolidation during hot rolling. The microstructure at different steps of composite material production was studied by scanning electron microscopy. Mechanical properties were evaluated by uniaxial tension tests at room temperature. The volume fraction of amorphous particles in the as-rolled state was about |0 %, and their size varied between 2 and 187 pm. The hardness of the obtained composite was 25 % higher as compared to the Al—5%Zn—5%Ca matrix alloy. At the same time, yield strength of the cladded composite material was two times higher than that of the matrix and cladding alloy samples.

Effects of microstructures of foam core on the thermal shock strength of ceramic foam sandwich structures

The effects of microstructures of foam core on the thermal shock strength of the sandwich slabs are investigated by macro-micro analysis. Each slab has two ceramic matrix composite (CMC) face sheets and an open-cell ceramic foam core. Asymmetric thermal shock fracture is evaluated at the macro continuum level. The position of the danger zone varying with the thickness of face sheets is determined. The finite element (FE) model based on the 3D Voronoi tessellations consists of a local micro-scale region surrounding the crack tip. For a calculated stress intensity factor in the macro model, the displacements along the boundary of the local model are calculated based on linear elastic fracture mechanics. The thermal shock strength of the sandwich structure is found to be dominated by the cell regularity, the cross-sectional shape of the cell struts and the relative density of foam core. The physical mechanisms responsible for those results are identified. The effective methods to improve the thermal shock resistance of the sandwich structures with ceramic foam core are proposed.

Effects of Microstructures of Foam Core on the Thermal Shock Strength of Ceramic Foam Sandwich Structures

The effects of microstructures of foam core on the thermal shock strength of the sandwich slabs are investigated by macro-micro analysis. Each slab has two ceramic matrix composite (CMC) face sheets and an open-cell ceramic foam core. Asymmetric thermal shock fracture is evaluated at the macro continuum level. The position of the danger zone varying with the thickness of face sheets is determined. The finite element (FE) model based on 3D Voronoi tessellations consists of a local micro-scale region surrounding the crack tip. For a calculated stress intensity factor in macro model, the displacements along the boundary of the local model are calculated based on linear elastic fracture mechanics. The thermal shock strength of the sandwich structure is found to be dominated by the cell regularity, the cross-sectional shape of the cell struts and the relative density of foam core. The physical mechanisms responsible for those results are identified. The effective methods to improve the thermal shock resistance of the sandwich structures with ceramic foam core are proposed.

Investigation on forming limit of carbon nanotube reinforced aluminum matrix composite sheet at high temperature

The thermal forming limit curve of carbon nanotube reinforced aluminum matrix composite (CNT/2009Al) was theoretically and experimentally investigated in this work. The mathematical procedure was solved on basis of Marciniak-Kuczynski model by applying the two constitutive equations of Swift equation and Voce equation. The influence of yield functions on FLD was analyzed by employing the general form of Hill’s 1979 yield criterion. The thermal Nakajima test was performed to determine FLD of the composite sheet. The result shows that, CNT/2009Al sheet formability is in a low level even at high temperature, and the FLD predicted by Hill’s 1979 makes a reasonable agreement with experimental data in right-hand zone.

Influence of chemical treatments on thermal and bonding behavior of carbon fiber-phenolic matrix composite

The performance of carbon fiber (CF) -Phenol matrix composite is mainly based on the inter-laminar shear force attraction between all the ingredients present in the composite. Basically, CF surface is smooth in nature in terms of its structure and have poor ability to allow the matrix material to stick to its surface. Hence, in this work an attempt is made to improve the bonding behavior between CF and phenolic matrix by performing three chemical treatment techniques on CF surface. The best chemical treatment method is suggested to use CF more effectively as reinforcement in polymer matrix composites. First, carbon fiber surface undergo thermal oxidation treatment. Second, carbon fiber surface is allowed to undergo HNO3 treatment and the third by deposition of multi walled carbon nano tubes functionalized (MWCNTs-F) on CF surface. CF-phenol matrix composite sheets are developed along with remaining ingredients using hand layup technique. The ability of uniform dispersion of all the ingredients for three composite sheets was observed by using scanning electron microscope (SEM). Thermo gravimetric (TGA) and Fourier transform infrared spectroscopy (FTIR) analysis is also performed on all sample powders and composite sheets to assess the thermal stability and bonding behavior of CF reinforced composite. Finally, the best chemical treatment method performed on CF is selected for the improvement of thermal and bonding behavior of CF-phenol matrix composite.Keywords: Multi walled carbon nano tubes; Carbon fibers, chemical treatments, Thermal and bonding analysis

Microstructure Evolution and its Modelling of Spray Deposited Al Matrix Composite Sheet during Wedge Pressing

Spray deposited SiCP/Al-Fe-V-Si composite is characterized with pores and oxide films between deposited particles, therefore further densification is needed. Densification of the composite preforms in large size has becomes the research emphasis and challenge. Current research of the composite is focused on densification technologies used to eliminate metallurgical defects. Key parameters of wedge pressing, density and stress distribution, flow behaviour, densification mechanism and regularity are investigated by combining experiment and finite element modelling. Pass reduction of 10%~15% and space of about 10mm between one end of the plate blank and the steel mould is beneficial to wedge pressing because of the effective deformation. Density and stress of the external layer are higher than that of the inter layer, density and stress distribution become uniform with overall reduction. Materials in preformed area flows along thickness direction as thickness of the plate decreases, while materials in main deformation area flows along length direction with increasing length of the plate. Wedge pressing of the spray deposited Al matrix composite plate follows porous metal plastic deformation mechanism under the condition of plane strain. Practical relative density of the plate is higher than the calculated value in the initial stage of pressing, while the practical relative density becomes lower than the calculated value as true strain exceeds 0.55, which can be attributed to the pores resulted from aggregation and breaking of SiC particles.

Deformation and fracture characteristics of Al6092/SiC/17.5p metal matrix composite sheets due to heat treatments

In metal matrix composite (MMC) materials, the reaction between the metal matrix and reinforcement particles could change the composition of the matrix and the interface and lead to interfacial compounds. These intermetallic compounds may have either a deleterious effect to the mechanical properties or beneficial effect in enhancing the toughness and ductility of the composite. An aluminium 6092 alloy with 17.5% volume fraction silicon carbide (SiC) particles sheet manufactured by means of powder metallurgical method, heat treated to T6 condition, is used to obtain a fundamental understanding of the heat treatment effect on the fracture mechanism, the microstructural changes and the interface between the Al-matrix and SiC particles. Changes in the microstructure of the Al/SiCp and the topography of the fracture are investigated using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) to characterize the precipitate and intermetallic compounds formed at the Al/Sic interface. X-ray diffraction (XRD) is utilized to characterize the phase formation and to give confidence in the results of TEM and EDS. Tensile tests with different strain rates (8 × 10−5, 8 × 10−4, 8 × 10−3, 8 × 10−2 and 0.16 s−1) were carried out to study the toughness and to find a correlation between the strain rate and heat treatment. Under T6 condition, the results show that the mechanical property of this MMC is less ductile due to the formation of precipitations as a result of either the interaction between the Al and SiCp or from hardening precipitation treatment, e.g. Al2Cu, Al4Cu2Mg8Si7 and MgAl2. O-condition annealing can reduce the detrimental effect of the intermetallic compounds in the interface region and improve the toughness and ductility of the material by decreasing the intermetallic compound (Al2Cu). However, the Al/SiC sheet treated with O-condition annealing is more sensitive to the strain rate than the one treated with T6.

Mechanical Properties and Microstructure of Mg-SiCp Composite Sheets Fabricated by Sintering and Warm Rolling

In this study, magnesium matrix composite sheets were fabricated by applying powder metallurgy and warm rolling methods. After preparing required mixtures of magnesium powder and SiC particles in different conditions, they were cold-pressed and sintered. Then, the sintered specimens were warm rolled through different numbers of passes. The effects of ball-milling process and the number of rolling passes were investigated on the tensile strength, hardness, microstructure, and fracture surface of magnesium matrix composites. The results were compared to those monolithic magnesium specimens (without reinforcement particle) produced in a way similar to that of the composites. The results show that among different factors (i.e., ball-milling process, the presence of SiC particles, and the number of rolling passes), the number of rolling passes is the most effective parameter on increasing the ultimate tensile strength (UTS),Vickers microhardness, and grain refinement. In this regard, UTS of the samples was increased at least 163% between second and sixth rolling passes. Moreover, for the sintered and six-pass rolled composite samples, microhardness and grain refinement were improved, respectively, about 30 and 70%.

Nanowire reinforcement of woven composites for enhancing interlaminar fracture toughness

A novel technique to improve the Mode I and Mode II interlaminar fracture toughness of woven carbon-fiber polymer matrix composite face sheets using zinc oxide nanowires is proposed. Zinc oxide nanowires are directionally synthesized on dry carbon fabrics that are used to manufacture the laminate. The influence of zinc oxide nanowires on interlaminar fracture toughness is compared against regular interfaces using double cantilever beam and end-notched flexure tests to provide fracture toughness values. A significant improvement in the Mode I and Mode II interlaminar fracture toughness values is observed with zinc oxide nanowires. Therefore, zinc oxide nanowire interlaminar reinforcement has been proven to enhance the interlaminar fracture toughness of textile composites.

AL2O3 TAKVİYELİ VE TAKVİYESİZ 7039 AL ALAŞIMLI LEVHALARDAN OLUŞAN TABAKALI KOMPOZİT MALZEMENİN ÜRETİMİNDE YENİ BİR YAKLAŞIM

In this study, Al2O3 particles with an average size of 6 μm were reinforced with 15% by weight of 7039 Al alloy matrix by Vortex method and metal matrix composite sheet was obtained. Reinforced 7039 Al alloy and unreinforced 7039 Al alloy sheet were placed in specially prepared mold after surface cleaning. The metal matrix composites placed in the furnace together with the mold were kept in the oven at 630 °C for 30 minutes until approximately 30% liquid, 70% solid consistency. Immediately after applying pressure of approximately 7 MPa to the semi-solid composite material in the mold removed from the furnace, the mold was placed in the annealing furnace in the same manner and left at approximately 600 ° C for approximately 4 hours. The new layered composite material formed by the joining of the plates cooled in the kiln mold to 500 oC temperature was removed from the mold and cooled in water. The microstructure and mechanical properties of the composite material were determined by optical microscope, micro hardness and tensile tests. Key words: 7039 Al alloy

Preparation of a novel layer-structured Ti3Al matrix composite sheet by liquid–solid reaction between Al foils and TiB/Ti composite foils

An alternative approach was successfully explored to produce fully dense Ti3Al matrix composite sheets using reaction annealing of the sandwich-structured (TiB/Ti)–Al laminates. It was noteworthy that the Ti3Al matrix composites displayed a unique multi-layered structure, composing of alternating TiB-rich layers and Ti3Al layers. Actually, TiB whiskers exhibited a layered distribution in Ti3Al layers, which was in favor of the equiaxed grain refinement in Ti3Al layers. Formation mechanism of the composites' laminated microstructure was elucidated. The multi-layered TiB–Ti3Al composites showed a significant increase in plasticity while maintaining or even improving the high tensile strength. Although the fracture toughness did not reach the desired level, however it was believed that the fracture toughness should be improved by means of increasing the long-aspect ratio of TiB whiskers and the volume fraction.

Thermal vibration characteristics of fiber-reinforced mullite sandwich structure with ceramic foams core

This paper researched a sandwich structure composed of fiber-reinforced mullite matrix composite face sheets and ceramic foams elastic layer subjected to high temperature and large gradient thermal environment. The vibration characteristics of the hybrid structure with free–free boundary condition were investigated in room and high temperature thermal environment by both experimental means and finite element method (FEM). Finite element models were established to estimate the vibration characteristics of the hybrid sandwich structure. Modal tests by hammer impulse method and exciter were carried out in room temperature environment to get the natural frequencies and corresponding modal shapes and damping loss factors. Then the exciter experiment was performed with the same setups as room temperature test to get the temp-varying vibration characteristics under high temperature thermal loads. The numerical simulation results agree well with the experimental results. The natural frequencies and damping loss factors of the hybrid sandwich structure show steady state with the temperature increased up to 800°C and so large gradient. Correspondently, the structural stiffnesses and damping characteristics of such composite structures keep excellent performance in thermal environment.

Transient liquid phase diffusion bonding of Al/Al2O3 nanostructured metal matrix composites

Transient liquid phase (TLP) diffusion bonding was carried out on nanostructured metal matrix composite sheets of Al-1100 alloy with 5 wt-% alumina particles at various bonding temperatures and process durations. A thin layer of 5 μm pure copper was electrodeposited as an interlayer. Joint formation was first attributed to the solid state diffusion of copper into the aluminium metal matrix followed by eutectic formation; then, base metal dissolution and isothermal solidification was completed at the joint interface. Joint area was characterised using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Diffraction patterns showed the formation of intermetallic phases like CuAl2. The concentration of Al2O3 particles increases across the interface as the bonding temperature increases. As a result, the highest bond strength of 123 MPa was achieved after a bonding duration of 30 min at 590°C.

Deep Drawing and Bulging Processes of Hard-Deformed Light Alloy Sheet with Resistance Heating

For enhance the heating efficiency and the formability of the magnesium alloy and aluminium matrix composite sheets, pulse current is adopted to the gas bulging and stamping processes. During the bulging process of magnesium alloy sheet, the effects of dynamic pulse current on the formed sheet combine both thermoelectricity and electro-plasticity. The effect and the applicability of the pulse current heating have been evaluated. The deformation properties, microstructure characteristics, and dislocation movement of the AZ31 alloy sheet during bulging process by the resistance heating are investigated. And the resistance heating has been adopted to improve the formability of SiCp/2024Al composites in stamping process. The pulse current density achieved 21.7A/mm2 and temperature of SiCp/2024Al composite correspondingly reached to around 400°C in the 50s. The results showed that stainless steel inserts between sheet and copper electrodes successfully prevented the heat dissipation and promote temperature uniformity over the sheet during electrifying. In addition, workpiece formed by the pulse current deep drawing shows better shape retention, surface quality and high geometry dimensional accuracy.