Metal Matrix Nanocomposites Research Articles

Mechanical characterization by multiscale indentation of particle reinforced Nickel-Alumina metal matrix nanocomposites obtained by high-kinetic processing of ball milling and spark plasma sintering

We report the mechanical characterization by multiscale indentation of particle reinforced dense Ni/Al2O3 metal matrix nanocomposites (MMNC) obtained by high-kinetic processing (HKP) of ball milling of the powders with a systematic variation of alumina nanoparticles fractions (from 1 to 20 vol. %) and spark plasma sintering (SPS). The morphology and particle size distribution of powder were evaluated as a function of milling time up to 10 h. Samples from the 10 h milled powders were densified by SPS. The mechanical properties of the sintered samples were obtained by micro and nanoindentation using diamond tips of Vickers and Berkovich geometry, respectively. The combination of HKP and SPS allowed a homogeneous dispersion of Al2O3 nanoparticles in the nickel matrix and effective reinforcing effects, which is the case of Ni/10 vol. % Al2O3 and Ni/15 vol. % Al2O3 samples. The highest hardness (4.68 ± 0.37 GPa) was obtained for Ni/15 vol. % Al2O3 MMNC, which is almost twice that of pure nickel (2.45 ± 0.22 GPa) processed at the same conditions. The highest elastic modulus (346 ± 30 GPa) was obtained for the Ni/10 vol. % Al2O3 sample. The analysis of the load-depth curves confirmed the reinforcing of the MMNCs as a function of the alumina particle content. Discussion of the possible reinforcing mechanisms is also included. The Ni/Al2O3 MMNC sintered specimens exhibit outstanding mechanical property results, which make them candidates for various high-temperature applications.

Thermal Analysis of Ni-Cu Alloy Nanocomposites Processed by Sand Mold Casting

Ni-Cu based alloy metal matrix nanocomposites are in great demand for advanced technological applications due to their high temperature, strength, and better thermal properties. The aim is to investigate the thermal conductivity and coefficient of thermal expansion of the nickel based alloy nanocomposites reinforced with titanium dioxide (TiO2) which varies from 3 to 12 weight % nanoparticulates (45 to 60 nm). The thermal conductivity was measured using a comparative cut bar method (ASTM E1225), and thermal expansion was analyzed using a push-rod dilatometer method (ASTM E228). From experimentation, it was observed that thermal conductivity of the nanocomposites activity increases with inclusion of the nanoparticles up to 9 weight % after descent due to the temperature effects in nanocomposites, and thermal expansion of the nanocomposites decreases with addition of the nanoparticles up to 9 weight % and further rises marginally due to ductility of composites. Due to the incorporation of hard ceramic particles into the matrix, the composites’ thermal conductivity increases to 57.42 W/m℃, and their thermal expansion decreases to 12 × 10−6. Nickel alloys are widely used in marine, automotive, valve, pump, and aircraft applications.

Experimental and numerical investigation on ZnP coated Mg-Mn based composite materials for internal fixation of tibia midshaft fracture: A comprehensive study

The study is aimed to assess the role of Ca10(PO4)6(OH)2 (HAp) and Zn3(PO4)2 (ZnP) bioceramics respectively as powder reinforcement and coating agent for magnesium alloys. The nano-sized HAp powder was synthesised and Mg-2Mn-1.5Zn (MZ21) and Mg-2Mn-1.5Zn/1HAp (MZ21/HAp) metal matrix nanocomposites were developed using vacuum-assisted stir casting process in Ar-SF6 protected environment. The chemical conversion coatings of ZnP were prepared on fabricated composites using Teflon lined stainless steel with zinc phosphate-based reaction solution. X-ray diffraction was used to assess the interaction of Mn and Zn on Mg crystal lattice. Microstructural observations were made using optical and scanning electron microscopy with energy dispersive X-ray spectroscopy. Mechanical properties were determined using tensile, hardness and dynamic mechanical analysis. Tensile yield and ultimate strengths of the MZ21 (60.31 ± 0.24 MPa, 142.83 ± 18.40 MPa) and MZ21/HAp (73.41 ± 2.24 MPa, 139.65 ± 16.16 MPa) showed a two-fold increase compared to pure Mg (30.36 ± 2.66 MPa, 73 ± 5.74 MPa). In-vitro studies indicated 10 % and 59 % improvement in cell viability, and 60 % and 33 % reduction in hemolysis rate respectively for MZ21 and MZ21/HAp by employing ZnP, and its bioactivity resulted in increased cell attachment. The effectiveness of the material was biomechanically evaluated and analysed using finite element approach. The results indicated that the developed composites reduced the mechanically shielded region and could provide enhanced healing in transverse tibial shaft fracture.

Stability analysis of a spinning soft-core sandwich beam with CNTs reinforced metal matrix nanocomposite skins subjected to residual stress

The stability of a soft-cored spinning viscoelastic sandwich beam and carbon nanotubes (CNTs) reinforced metal matrix nanocomposites (MMNCs) skin subjected to residual stress have been investigated. The metal matrix nanocomposites (MMNCs) skins are symmetrical and isotropic. In addition, these skins reinforced with uniform and functionally graded (FG) distributions of carbon nanotubes (CNTs) are considered. The soft-core of the sandwich beam is deemed to be elastomeric and has internal damping of viscoelastic type. The skin layers of the sandwich beam are subject to residual stresses caused by the production process. Also, the effective material properties of skins are obtained using the rule of mixture (ROM) and Halpin-Tsai (H-T) micromechanics models. First, the governing equations of motion of a spinning viscoelastic sandwich beam are obtained using the Hamilton principle. Then, the sandwich beam's natural frequencies are calculated using the differential quadrature method (DQM). The effects of CNTs distribution, nanotube volume fraction, spinning speed, critical loading, the thickness of the core, axial force, and residual stress on the sandwich beam's natural frequency and stability regions are investigated. According to the results of this study, based on the sandwich beam's different spinning speeds, it is possible to estimate the optimal amount of core thickness to prevent instability, which can be very important in the design of spinning sandwich structures.

Influence of Extrusion Rate on Microstructure and Mechanical Properties of Magnesium Alloy AM60 and an AM60-Based Metal Matrix Nanocomposite

Metal matrix nanocomposites are attracting attention because of their great potential for improved mechanical properties and possible functionalization. These hybrid materials are often produced by casting processes, but they can also develop their property profile after hot working, e.g., by forging or extrusion. In this study, a commercial cast magnesium alloy AM60 was enriched with 1 wt.% AlN nanoparticles and extruded into round bars with varied extrusion rates. The same process was carried out with unreinforced AM60 in order to determine the influences of the AlN nanoparticles in direct comparison. The influence of extrusion speed on the recrystallization behavior as well the effect of nanoparticles on the microstructure evolution and the particle-related strengthening are discussed and assessed with respect to the resulting mechanical performance.

An order statistic approach for inference of the size distribution of 3D particle clusters in metal matrix nanocomposites

Metal matrix nanocomposites (MMNCs) become popular in recent decades due to their superior properties over traditional materials, like high strength and light weight. They are fabricated by dispersing nanoparticles into molten metal matrix. If nanoparticles are not well dispersed and form clusters in the metal matrix, the mechanical properties of the MMNC would be greatly affected. It is crucially important and useful if the size of three-dimensional (3D) clusters in the metal matrix can be extracted for process characterization. This paper proposes a novel approach based on order statistic theory to infer the size distribution of 3D particle clusters based on their two-dimensional (2D) cross-sectional microscopic images. The novelty of this idea is that it utilizes information from only the few largest 2D clusters, hence eliminating the practical difficulties in correctly identifying and accurately measuring the radii of small clusters. The joint probability distribution of the l largest 2D cluster radii is linked to the distribution of the 3D cluster size, based on which then maximum likelihood estimation (MLE) method is used to infer the 3D cluster size distribution. Extensive simulation studies and real cases have demonstrated the effectiveness, efficiency and robustness of the proposed approach compared to the existing methods.

Machinability of squeeze cast (TiB2+CNT)/Al 7075 metal matrix nano-composite during EDM with untreated and cryogenic treated Cu electrodes: A comparative study

This paper accentuates investigation of machining responses and surface integrity of (TiB2+CNT) reinforced Al 7075 metal matrix nano-composite intended for aerospace and automotive applications, which was processed through modified liquid metallurgy squeeze casting route. Microstructure of the developed composite was investigated through scanning electron microscopy, elemental distribution was identified through Energy-dispersive X-ray spectroscopy and mechanical properties were determined following recommended ASTM standards. However, focus was emphasized on exploration of the influence of peak current ( IP), pulse-on time ( TON), and gap voltage ( VG) on material removal rate (MRR), tool wear rate (TWR), and surface integrity during electrical discharge machining of the hybrid nano-composite with untreated and cryogenic treated Cu tools. MRR, TWR, and average roughness ( Ra) of the machined surfaces showed distinctive pattern in their variations when the machining parameters were changed; however, hardness of the machined surfaces did not show any specific trend with respect to the increase of the considered parameters. Cryogenic treated Cu tools outperformed the untreated tools, as perceived from the experimental results. For instance, while machining at TON = 100 µs, VG = 55 V, and IP = 10 A, maximum MRR for untreated tools was 27.43 mm3/min, and that for cryogenic treated tool was 29.12 mm3/min, leading to an improvement of about 5.8%. But at VG = 55V, IP = 4 A, and TON = 300 µs, maximum MRR for untreated tools was 16.71 mm3/min, and that for cryogenic treated tool was 18.22 mm3/min, leading to an improvement of about 8.3%. Similarly, at IP = 4A and TON = 100 µs and VG = 75V, maximum MRR for untreated tools was 14.88 mm3/min, and that for cryogenic treated tool was 22.7 mm3/min, leading to an improvement of about 34.4%. Similar outperformed results for cryogenic treated tools were also achieved while analyzing the experimental results of TWR, surface hardness and Ra. Finally, surface defects were analyzed through SEM at the disparate parametric combinations.

Fatigue life, distortion behavior of AA 8011- nano B4C composite using simulated acoustic emission technique – An experimental and statistical appraisal

The high quality AA8011 aluminium alloy dispersed with different percentages of nano-sized B4C (0, 0.5,1 and 1.5 wt%) was fabricated by electromagnetic frequency high energy stir casting technique. The characterization study on metal matrix nanocomposites (MMNC) using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Spectrum (EDS), and X-ray Diffraction (XRD) confirmed the morphology and distribution of AA8011 with nano B4C. The microhardness analysis and strength using Vickers hardness testing and Electromechanical Universal Testing Machine, respectively, show significant mechanical properties improvement. The ductility study on Scanning Electron Microscope (SEM) images of the fractured samples reveal the transition from ductile to brittle nature in MMNCs. The online monitoring using Acoustic Emission (AE) during a tensile test indicates the mitigation in crack generation and its propagation. The substantial enhancement in fatigue life by the addition of nano B4C was evidenced by testing at a stress ratio (R = 0.1) and statistically significant (at p < 0.05) by one way Analysis of Variance (ANOVA). The SEM Fractography of fractured fatigue samples discloses the influence of dispersal of nano-sized reinforcements which resist fatigue crack growth. The result demonstrates that AA8011-1.5 % nano B4C composite has improved hardness, higher tensile strength and fatigue strength than the pure matrix due to the addition of the B4C.

Exploring MgO/HA ceramic nano-composites for biodegradable implants: Exploring biological properties and micromechanics

The release of Mg ions from Mg-based implants during biodegradation can promote bone repair through osteoblast migration. However, the high pH values (alkaline stresses) associated with this process can be harmful for osteoblasts. Therefore, surface modifications are required which allow to adjust the Mg ion concentration within a tolerable range. The present work investigates the effect of anodizing of magnesium/hydroxyapatite metal matrix nano composites (Mg/HA-ncomposites) on micromechanical behavior and on biological properties. The results will be implemented into a design strategy for improved Mg/HA-ncomposites. The HIPed Mg/HA-ncomposites with varied content of nano hydroxyapatite (n-HA) particles (0, 0.75, 1.8, and 3 wt%) were anodized in a 6 M KOH solution at 1.50 V and 50 °C for 2 h to develop magnesium oxide/hydroxyapatite surface ceramic matrix nano-composite (MgO/HA-ncomposite). The specimens were evaluated by immersing the materials into simulated body fluid (SBF), seeding of human mesenchymal stem cells on the surfaces, and performing nano-indentation and nano-scratch tests. The results show that the uniform distribution of 1.8 wt% n-HA particles in the MgO converted layer strengthens its adhesion as compared to the other types of MgO/HA-ncomposites. Furthermore, the cell spreading of human mesenchymal stem cells on the composite of 1.8 wt% n-HA improves after the anodizing process and after a one-day cell culture. In summary, the present combined micromechanical and biological study has shown that the MgO/HA-ncomposite of 1.8 wt% n-HA represents a promising biomaterial for bio-absorbable bone implants and that it outperforms pure Mg-surfaces.

Nanostructured t-YSZ/Fe3O4 powdered composite obtained via AACVD method as a promising reinforcing material for metal matrices

This work reports the synthesis and microstructural characterization of a powdered composite comprised of tetragonal yttria-stabilized zirconia and cubic magnetite, fabricated using the aerosol-assisted chemical vapor deposition technique. Extensive characterization of the microstructure confirmed the formation of a powdered composite, which exhibited a spherical morphology with an irregular topography. Small amounts of monoclinic ZrO2 and Fe2O3 were also found as components of the particles. The particles exhibited a crystallite size of about 2 ± 0.5 nm. Additionally, several testing probes were prepared to assess the improvement of the mechanical properties of an Al-based metal matrix nanocomposite. The probes were prepared by mixing Al with different amounts of the particles (0.5–2.5 wt%). The addition of 1 wt% of particles exhibited the most significant results, with hardness and Yield Strength values of nearly 3 times higher than those for pure Al, while an increase of 119% in the elastic modulus was measured.

An investigation on microstructure and mechanical behaviour of aluminium hybrid metal matrix nanocomposite fabricated through electromagnetic stir casting process

This study focuses on the microstructure characteristics and mechanical properties of unreinforced and reinforced ceramic materials titanium diboride (TiB2) and graphite (Gr). Aluminium hybrid metal matrix nanocomposites reinforced with varying weight percentage of nano TiB2 (0-12.5 wt. %) and nano Gr (4wt %) via electromagnetic stir casting process to produce hybrid nanocomposites samples. Identification of phases and microstructure analysis are performed through X-ray diffraction, Optical Microscope and Scanning Electron Microscope with Energy Dispersion X-ray Spectrum. Mechanical properties such as hardness, tensile, compression and flexural strength were investigated on the prepared hybrid nanocomposites samples. Microstructure images of the samples reveals uniform dissemination of reinforced TiB2 and Gr nanoparticles in Aluminium base matrix and X-ray diffraction confirms the presence of reinforced particles TiB2 and Gr in Aluminium base matrix. Concluded from the consolidated samples, mechanical properties of the reinforced samples improved as compared to the matrix material.

Effect of in-situ reaction time on the strength of AA5052/ZrAl3 metal matrix nano composites

ABSTRACT In the present investigation, AA5052 metal matrix nanocomposites (MMNCs) reinforced with ZrAl3 particles were fabricated using an in situ reaction. The study focuses on the effect of variation in vol.% of reinforcement particles and reaction time on phases, microstructure and tensile strength. Potassium hexafluoro zirconate (K2ZrF6) salt was used for the fabrication of 3, 6, 9 and 12 vol.% of ZrAl3 particles in the matrix. The increase in wt.% of salt and reaction time increases the vol.% of ZrAl3 particles and distributes the nanoparticles homogeneously in the matrix, respectively. Tensile strength and yield strength improved with the increase in vol.% of ZrAl3 particles and increase in reaction time.

Investigation of structural, mechanical, and corrosion properties of steel 316L reinforcement by hBN and TiC particles

The powder metallurgy process is commonly used to produce nanocomposite samples so that, their properties depend on the process parameters and the weight fraction of reinforcements. In the current study, producing metal matrix nanocomposite with steel 316L as a matrix and mixing of hBN/TiC nanoparticles as a reinforcement is conducted. The total weight percentages of reinforcements are 6% wt and 8% wt (i.e. with an equal proportion for each nanoparticle). The powders were mixed for 10 h and then compacted at different pressures (300 MPa and 400 MPa) by cold isostatic pressure (CIP) conditions. The compacted powders were sintered at different temperatures (1350 °C and 1450 °C), and times (2 h and 4 h) in the furnace. The microstructural analysis of nanocomposite was performed by SEM, XRD, EDX, DTA, and also FT-IR tests. The results showed that by increasing the weight fraction of nanoparticles the microhardness and wear rate improved and, on the contrary, the flexural strength and corrosion rate decreased. The optimum result for the microhardness and wear rate were achieved when the sample contains 8% wt nanoparticles, compacted at 400 MPa and sintered at 1350 °C for 4 h. As well, the highest flexural strength and corrosion rate belong to the sample compacted and sintered at 400 MPa, 1450 °C for 2 h.

An Investigation into the Microstructure and Mechanical behavior of Aluminium Hybrid Metal Matrix Nanocomposite

An Investigation into the Microstructure and Mechanical behavior of Aluminium Hybrid Metal Matrix Nanocomposite

Mechanical, microstructural and electrical properties of Al7075/SiC based hybrid composites with nano B4C, Graphene and CNT reinforcements

Superfluous properties of Graphene and CNT reinforced composites are making significant revolution in the application area of metal matrix nano-composites. Fabrication of these composites without any flaw is the challenging task due to its inherent properties such as limited wettability, unique structure, load transfer efficiency, shape and size. The individual reinforcements such as 0.1wt.% B4C, 0.1wt.% Graphene and 0.1wt.% CNT were successfully incorporated in common Al7075/10wt.% SiC base through squeeze casting method combined with ultrasonic vibration. The influence of reinforcements on the mechanical, metallurgical and electrical properties of the composites was analysed in this study. The hardness value of the B4C-based, Graphene-based and CNT-based composites has enhanced to 167 BHN, 145 BHN and 135 BHN respectively from the base matrix. Tensile strength has also improved to 239 MPa, 324 MPa and 308 MPa. In the case of micro-structural characteristics, the addition of Graphene in the Graphene reinforced composite improved the grain structure due to the grain refining effect followed by the CNT and B4C reinforced composites with the similar weight fraction and processing methods. The influence of various reinforcements was analysed using Optical Microscope (OM), Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray analysis (EDX) techniques. Addition of Graphene and CNT increased the electrical conductivity of respective composites to 24.2 MS/m and 21.1 MS/m.

Effect of nano ZrB2 particles on physical, mechanical and corrosion properties of Al6061 metal-matrix nano composites through stir casting route

The present study investigated the microstructure, mechanical and corrosion behaviour of Al6061 alloy reinforced with nano zirconium diboride (ZrB2) particles. The stir casting route is carried out to fabricate the Al6061 metal matrix nanocomposites (AMMNCs) by varying 0 to 2 Wt% of ZrB2 nanoparticles. X-ray Diffraction (XRD)was used to study the crystalline size and phase distribution of AMMNCs. Scanning electron microscope (SEM) analysis reveals the uniform dispersion of ZrB2 nano particulates in AMMNCs. Ultimate tensile strength and yield strength, hardness of the AMMNCs were increased by 33.58%, 27.54%, and 40.57%, respectively, with the addition of ZrB2 nano particulates, while the elongation decreased to 46.03%. with the increase in ZrB2 Wt%. The corrosion rate of AMMNCs (2 Wt% ZrB2) decreased by 86% compared to Al6061 alloy. Fracture analysis of the samples showed that the fracture behaviour of Al6061 matrix alloy changed from ductile intergranular fracture to cleavage. The results show that the developed nanocomposite enhances mechanical properties and corrosion resistance with an increase in Wt% of reinforcement.

Effects of milling time on sintering properties and formation of interface Al4C3 on graphite reinforced Al-4.5Cu-1.5Mg nanocomposite

Aluminum-based metal matrix nanocomposites have been extensively researched and developed for aerospace and automotive applications. Al-4.5Cu-1.5Mg with 0.5 wt% graphite were milled for 2 h, 4 h, 6 h, and 8 h using shaker mill under argon gas. The phenomena of deformation, fracturing, and cold welding during shaker mill were investigated to observe how the shaker mill effects on their morphology and formation of intermetallic phases due to its very high speed. Sintering under ultra-high purity argon gas for 99.9999% was done to produce high density materials. Intermetallic phase Al4C3 was found as a result reaction between aluminum and graphite during milling. Formation of Al4C3 is very important to the alloy as an interface between matrix and reinforcement particle in order to have higher hardness. A decrease in Peaks Cu and followed by an increase in Al2Cu precipitation in the XRD pattern occurred with increasing milling time. The role of Al2Cu precipitation is very important in improving mechanical properties, resulting in the highest hardness value reaching 97 HV and a density value of 83% at 8 h of milling.

Synthesis and Characterization of Fe2O3 Nanoparticles Reinforced to Recycled Industrial Aluminium Scrap &amp; Waste Aluminium Beverage Cans for Preparing Metal Matrix Nanocomposites

Increased material demand in all sectors is primarily due to exponential growth in population to fulfill human needs and comforts. Recycling of collected aluminium beverage cans and Al 6061 alloy scraps from industries ensures energy savings with reduced environmental problems in fabricating composite parts economically. The iron oxide (α-Fe2O3) nanoparticles were prepared by precipitation method using ferric chloride and ammonia as a precursor. The prepared nanoparticles were characterized by using Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR). Stir cast processing route ensures uniform mix of reinforcement nanoparticles in matrix material. The prepared nanocomposites (matrix: Al Scrap (90% Scrap Al 6061 alloy + 10% Waste Al can); reinforcement: 2%, 4% and 6% wt. of Al matrix) were mechanically characterized for hardness and tensile strengths. It was observed that, increased percent of Fe2O3 nanoparticles in the metal matrix nanocomposite (MMCs) resulted in significant increase in hardness and tensile strength values. Fractography analysis examined viz. scanning electron microscope (SEM) revealed a ductile failure for as-cast Al scrap followed by brittle failure in Al MMC's.

Micromechanical constitutive modeling of tensile and cyclic behaviors of nano-clay reinforced metal matrix nanocomposites

Metal matrix nanocomposites are emerging rapidly among both research and industry communities. Nonetheless, the studies for their use in Low-Cycle Fatigue (LCF) applications are rarely documented. Prior to tailoring the microstructure for the desired LCF performance, it is a fundamental task to understand the structure-property correlations of the nanocomposites. In the present paper, a continuum-based micromechanical model starting from the nanostructure is proposed to fulfill such a task. The proposed model is applied to a piston aluminum alloy reinforced with 1 wt% nano-clay subjected to fully-reversed strain-controlled LCF loading at room temperature. The model, formulated within Eshelby's inclusion framework, considers the active clay/matrix interactions, the intercalation/exfoliation effect via the equivalent stiffness method, and the size effect through the introduction of the interphase thickness as a characteristic length scale. To render the model able to reproduce the cyclic hysteretic behavior of the nanocomposites, the isotropic/kinematic hardening rule is considered to describe the aluminum alloy plasticity. The model results are favorably compared to the experimental observations in terms of monotonic and cyclic elastoplastic stress-strain responses of the aluminum/clay nanocomposite. A parametric study is then carried out in order to understand the separate and synergic effects of clay weight fraction, clay geometrical parameters (e.g., shape and size), and clay structural parameters (e.g., number of silicate layers and interlayer spacing) on the overall monotonic and cyclic responses of the present nanocomposite. The reinforcing effect of each parameter is discussed concerning the micromechanical model.

Use of Fumed Silica Nanostructured Additives in Selective Laser Melting and Fabrication of Steel Matrix Nanocomposites.

The advancement of additive manufacturing (AM) for metal matrix nanocomposites (MMNCs) is gaining enormous attention due to their potential improvement of physical and mechanical performance. When using nanostructured additives as reinforcements in 3D printed metal composites and with the aid of selective laser melting (SLM), the mechanical properties of the composites can be tailored. The nanostructured additive AEROSIL® fumed silica is both cost-effective and beneficial in the production of MMNCs using SLM. In this study, both hydrophobic and hydrophilic fumed silicas were shown to successfully achieve homogenous blends with commercial 316L stainless steel powder. The powder blends, which exhibited better flow, were then used to fabricate samples using SLM. The samples’ microstructure demonstrated that smaller grains were present in the composites, resulting in improvements in mechanical properties by grain refinement compared to those of 316L stainless steel samples.