Traditional Metallic Materials Research Articles

Phase field simulation of spinodal decomposition in Zr–Nb alloys for implant materials

Zirconium (Zr)-based alloys, a new class of hard-tissue replacement materials, show lower strength compared to traditional medical metal materials such as stainless steel, cobalt alloy, and Ti-6Al-4V alloys, which may lead to premature fracture of the implant. Spinodal decomposition can increase the strength greatly without an increase in the elastic modulus of the alloy. In this study, a phase field method based on the Cahn–Hilliard equation was applied to the simulation of the spinodal decomposition in Zr–Nb alloys. The spinodal region on the Zr–Nb phase diagram was calculated by the phase field method by considering the interfacial energy and elastic strain energy contribution to the total Gibbs free energy. Furthermore, the effects of the Nb content and heat-treatment temperature on the morphology, amplitude, and volume fraction of the decomposition phases are discussed. Simulation results indicate that the morphology of the β′ phase is interconnected and regular with a preferential alignment in the ⟨110⟩ direction to reduce the strain energy, which may restrict the spinodal decomposition of the alloys. The two droplet phases merge, which can be attributed to the reduction in the elastic strain energy. The phase decomposition rate increases with an increase in aging temperature, but the aging temperature has only a small influence on the final volume fraction of the β′ phase.

Ablation behavior of glass fiber reinforced polybenzoxazine composites irradiated by high energy continuous-wave laser

Laser, especially high energy continuous-wave (CW) laser, can destroy traditional metal or polymer materials in an extremely short time. Although polybenzoxazine-based composites have been applied in many fields, its laser ablation behavior is still unclear. In this case, glass fiber reinforced polybenzoxazine composites are successfully prepared and irradiated by high energy CW laser to specifically study the laser-induced damage. Results show that laser parameters including power density and irradiation duration have an obvious effect on the damage. The poor graphite structure of residual char has a slight improvement under laser irradiation. The mixture of residual char and melted glass fiber can cover the surface of ablation region and prevent from oxidation. According to the micro-morphology and element analysis, the current paper gives a good understanding to the high energy laser-induced damage mechanism of the polybenzoxazine-based composites.

Polymer Electrode Materials for High‐Performance Lithium/Sodium‐Ion Batteries: A Review

Newly developed charge storage and charge transport materials, such as organic polymers, demonstrate promise for applications in secondary batteries. Currently, such organic materials are regarded as promising candidates as substitutes for traditional metal materials for energy storage equipment because of advantages such as structural diversity, abundance, and environmental friendliness. The structural characteristics, electrochemical reaction mechanism, and properties of polymer electrode materials are comprehensively introduced. In addition, recent progress on implementing polymer‐based materials in lithium‐ and sodium‐ion batteries, as well as problems associated with the development of polymer electrodes, are discussed.

Nonbasal Slip Systems Enable a Strong and Ductile Hexagonal-Close-Packed High-Entropy Phase.

Linear defects, referred to as dislocations, determine the strength, formability, and toughness of crystalline metallic alloys. The associated deformation mechanisms are well understood for traditional metallic materials consisting of one or two prevalent matrix elements such as steels or aluminum alloys. In the recently developed high-entropy alloys (HEAs) containing multiple principal elements, the relationship between dislocations and the mechanical behavior is less understood. Particularly HEAs with a hexagonal close-packed (hcp) structure can suffer from intrinsic brittleness due to their insufficient number of slip systems. Here we report on the surprisingly high formability of a novel high-entropy phase with hcp structure. Through insitu tensile testing and postmortem characterization by transmission electron microscopy we reveal that the hcp phase in a dual-phase HEA (Fe_{50}Mn_{30}Co_{10}Cr_{10}, at. %) activates three types of dislocations, i.e., ⟨a⟩, ⟨c⟩, and ⟨c+a⟩. Specifically, nonbasal ⟨c+a⟩ dislocations occupy a high line fraction of ∼31% allowing for frequent double cross slip which explains the high deformability of this high-entropy phase. The hcp structure has a c/a ratio of 1.616, i.e., below the ideal value of 1.633. This modest change in the structure parameters promotes nonbasal ⟨c+a⟩ slip, suggesting that ductile HEAs with hcp structure can be designed by shifting the c/a ratio into regimes where nonbasal slip systems are activated. This simple alloy design principle is particularly suited for HEAs due to their characteristic massive solid solution content which readily allows tuning the c/a ratio of hcp phases into regimes promoting nonbasal slip activation.

Numerical simulation of pin-loaded joints of fiber metal laminate

Fiber metal laminate (FML) is an advanced composite material, which consists of metal layers and polymer matrix composites. Due to the combination of the advantages of traditional metal and composite materials, FML has been widely used in the aircraft industry. Due to advantages in inspection and reliability, the mechanically fastened (riveted or bolted) joints are essential for a complex structure. The present study investigated the effects of geometry parameters and ply stacking sequences on the mechanical properties of pin-loaded FML joints. A three-dimensional progressive failure model had been created to investigate the failure response of FML joints. A comparison between simulation and experimental results showed a good agreement on the strength and internal damage pattern (fiber damage, matrix damage, and cohesive layer delamination between 0° fiber and outer aluminum) for the pin-loaded FML joints. It was found that ultimate failure strength increased with the increase of width-to-diameter ratio (W/D) or edge distance-to-diameter ratio (E/D). The failure modes of pin-loaded FML joints were dissimilar by varying the ratios of W/D and E/D. The dominant failure mode of studied joints was bearing failure mode. Numerical simulation results showed that ply stacking sequence has obvious effects on the mechanical properties of FML joints.

Influences of Interfaces on Dynamic Recrystallization and Texture Evolution During Hot Rolling of Graphene Nanoribbon/Cu Composite

The influences of rigid heterointerfaces on the dynamic recrystallization (DRX) process and texture evolution during hot rolling of a graphene nanoribbon (GNR)-reinforced Cu-matrix composite system are investigated. The Cu/GNR interfaces contribute to the atypical recrystallization-type and brass-type textures developed in composites within 0.5 and 3 vol pct GNRs, respectively, deviating from the normal Cu-type texture found in their pure Cu counterpart. The heterointerfaces may change the texture evolution of the Cu matrix in four ways, namely, retard the dislocation cross slip, activate partial slip, generate geometrically necessary dislocations, and promote the DRX process. These are corroborated through viscoplastic self-consistent simulations, which well reproduce the texture development in all samples by considering the interface–dislocation interactions, the activation of non-normal slip, and the interface-driven DRX nucleation. This study suggests the possibility of manipulating the microstructure, texture, and mechanical properties of traditional metallic materials through the design of heterophase interfaces.

Fabrication of PPy Nanosphere/rGO Composites via a Facile Self-Assembly Strategy for Durable Microwave Absorption.

Traditional magnetic metal and alloy materials suffer from easy oxidation and high density, which hinders their practical application as high-performance microwave absorbers. Lightweight and durability have become new goals in the fabrication of the next generation of microwave absorbers. Herein, we report the synthesis of polypyrrole (PPy) nanosphere/reduced graphene oxide (rGO) composites through chemical reduction of self-assembly PPy nanosphere/GO hybrids. PPy nanospheres and GO are integrated effectively by π–π interaction of dual conjugated systems. When the mass ratio of PPy nanospheres to rGO is 0.6:1, the resultant composite, PPy/rGO-0.6, presents comparable/superior reflection loss characteristics to those magnetic metals and their related graphene-based composites in previous studies. Electromagnetic analysis reveals that well-matched characteristic impedance, multiple polarization loss, and good conductivity loss are, together, responsible for the excellent microwave absorption performance of PPy/rGO-0.6. More importantly, PPy/rGO-0.6 also exhibits good microwave absorption after being treated at 423 K for a long time. This work provides a new idea for designing and preparing a high-performance microwave absorber with lightweight and durable features.

Experimental research on surface roughness of milling medical magnesium alloy

Magnesium alloy is more suitable for biomedical metal material compared with traditional metal materials, as it has the similar mechanical properties with human bone and biodegradable property. Surface roughness influences the friction and ware properties, corrosion resistance and fatigue resistance, then the service life of parts. It is important to search the influence of magnesium alloy milling process on surface roughness as a certain connection exists between roughness and corrosion resistance. In this paper, the influence of cutting speed, feed, axial and radial depth of cut on surface roughness had been analyzed after the orthogonal milling experiments. Finished surface roughness model had been established and verified.

Damage Mechanism Analysis of Carbon Fiber Composites under Compressive Load

Carbon fiber composite material with light weight, high strength, corrosion resistance and other characteristics of its impact damage mechanism is different from the traditional metal materials. In this paper, the quasi-static compression of carbon fiber composites was carried out by using a material testing machine to analyze the damage mechanism. The Hopkinson bar technology was used to test the dynamic mechanical properties. The damage mechanism of the carbon fiber composites under dynamic compressive loading was studied. Stress - Strain relationship of composites under Quasi - static and dynamic compressive load. It is found that the main failure mode of out-of-plane direction of carbon fiber composite laminates is brittle shear failure, while the in-plane failure mode shows the properties of brittle materials.

Enhanced Osteoblasts Responses to Surface-Sulfonated Polyetheretherketone via a Single-Step Ultraviolet-Initiated Graft Polymerization

Polyetheretherketone (PEEK) has the potential to replace traditional metallic materials as an orthopedic and dental implant because its elastic modulus is similar to natural bone, although its intrinsic bioinertness hampers its clinical application. In this study, sulfonate groups were introduced onto the PEEK surface through a single-step ultraviolet-initiated graft polymerization of vinylsulfonic acid sodium. Diffuse reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the successful attachment of sulfonate groups to the PEEK surfaces. A decreased angle of contact suggested there was an increase in hydrophilicity as a result of endowing the PEEK surface with sulfonate groups. Atomic force microscopy revealed there to be no significant changes in surface topology and roughness as a result of the surface modification. In vitro cell adhesion, viability assay, alkaline phosphatase activity and extracellular matrix mineralization analyses, and real-time ...

A new method for the automated design of cooling systems in injection molds

This paper presents a new method for the automatic design of the cooling system in injection molds, based on the discrete geometry of the plastic part. In a first phase the new algorithm recognizes the discrete topology of the part, obtaining its depth map and detecting flat, concave regions and slender details which are difficult to cool. The algorithm performs an automatic analysis of the heat transfer, taking into account functional parameters, in order to guarantee a uniform cooling of the part. Based firstly on the limit range distance from which the horizontal straight channels lose cooling effectiveness and secondly on the depth map data, the algorithm provides an optimal layout for the cooling system of the part by adapting it to its geometry. By means of adapting the precision of the algorithm to the molded geometry, both horizontal straight channels for low concavity areas and baffle matrices for concave regions are used. In a second phase, the parameters of the cooling system such as channel diameter, channel separation, etc., are dimensioned by means of genetic optimization algorithms. A second genetic optimization algorithm ensures uniformity and balance in the layout of the cooling system for the plastic part. The result is the design of the cooling system for the plastic part with the same performance as the conformal system. A constant distance between the cooling channels and the part surface is maintained, and at the same time the manufacturing of the mold using CNC techniques and traditional metal materials could be achieved. Complementarily, the algorithm performs an interference analysis with other parts of the mold such as the ejection system. The method does not need a subsequent CAE analysis since it takes into account functional and technical parameters related to heat transfer in its design, thus ensuring its functionality. The algorithm is independent of the CAD modeler used to create the part since it performs a recognition analysis of the part surfaces, being able to be implemented in any CAD system. The data obtained in the design can be used additionally in later applications including the automated design of the injection mold.

Enhancement of evaporative heat transfer on carbon nanotube sponges by electric field reinforced wettability

Phase-change thermal management devices are the most effective approach to managing the increasing redundant heat in integrated electronic chips. The cooling performance of phase-change thermal management devices can be obviously enhanced via micro- and nano-structured materials with special wettability. Here, carbon nanotubes (CNTs) sponges are fabricated, and the strategy to enhance evaporative heat transfer properties on the CNTs sponges by electrowetting method is presented. The electrowetting method induces a higher degree of wettability of porous CNTs sponges, which results in spreading and even permeation of the liquids without any physical or chemical treatment. In this case, the electrowetting method could lead to a much better evaporative heat transfer properties. Specifically, evaporation areas and evaporation rates of liquids on CNTs sponges are enlarged about 5–7 times and 2.8–10.5 times by the electrowetting method, respectively. The electrowetting method also induces much better temperature uniformity properties that play vital roles in phase-change thermal management devices. The CNTs sponges also have chemical stability and are light-weight versus traditional metallic materials. Thus, our work reported here is a promising opportunity to enhance the evaporative heat transfer properties of liquids with a profound influence on thermal management techniques.

The evaluation of electromagnetic shielding properties of CFRP/metal mesh hybrid woven laminated composites

Carbon fiber-reinforced plastic (CFRP) composites, owing to their lightweight and strength-weight ratio, are being used in many applications to replace traditional metallic materials and their alloys. The combination of polymeric composites with metallic materials can provide a significant impact in engineering applications. This paper evaluates electromagnetic interference shielding of bimetal-carbon prepreg fibers textile composite materials. Prepreg carbon fibers and metal wire mesh are used to make electromagnetic interference shielding samples. The material samples consist of making plain weaves of metal wire mesh and carbon prepreg and stack them with prepreg carbon fiber layers. In order to produce plain woven fabrics, wefts were made of prepreg carbon fibers and warps were made of wire meshes. In each woven fabric, two yarns of different metal wire meshes were alternated one after another. The combination of conductive wire meshes such as stainless steel-copper, stainless steel-nickel, and copper-nickel in a woven fabric was considered. The electromagnetic shielding effectiveness was evaluated for each textile composite material based on ASTM 4935-99. Results showed a possible application of these materials for electromagnetic interference shielding with higher absorption. The best electromagnetic interference shielding performance was obtained for a combination of stainless steel-copper-CFRP with a shielding effectiveness of 131.6 dB. The absorption losses for all samples were about 82% of electromagnetic interference shielding effectiveness. The mechanical properties and scanning electron image of fabricated samples were also investigated.

(Invited) Developing Environmental Barrier Coatings Resistant to Molten Calcium-Magnesium-Aluminosilicate (CMAS)

In order to improve fuel efficiency in commercial aircraft engines, ceramic matrix composites (CMC) are considered a leading material system to replace metal-based turbine engine components, due to their lower density and high-temperature capabilities compared with traditional metallic structural materials. However, silicon-based CMCs are susceptible to oxidation and corrosion in the harsh combustion environment found in air-breathing turbine engines. Environmental barrier coatings (EBCs) are being developed and applied to protect and to enhance durability and service life of CMC components for application in the hot-section of engines. The development of robust EBCs is threatened by sand, volcanic ash and other particulate debris, which are routinely ingested by aircraft engines in varying geographic regions. At temperatures >1200°C, these particulates melt, yielding molten calcium-magnesium-aluminosilicate (CMAS) deposits. These deposits can significantly reduce the durability of present and future engine component materials, particularly EBCs designed to protect silicon-based ceramic matrix composites (CMC). Near target operating temperatures (~1500°C) of future CMC-based aircraft engines, molten CMAS behaves like a viscous melt that can infiltrate and chemically interact with protective coatings, causing premature failure of the EBC system and ultimately the overall CMC engine component. Degradation of candidate EBC materials based on rare-earth silicates by molten CMAS will be presented with a focus on recent work, as well as methods of evaluating the complex high-temperature materials interactions, accomplished at NASA Glenn Research Center.

Winding orientation optimization design of composite tubes based on quasi-static and dynamic experiments

Compared with traditional metal materials, composite materials can be better designed by changing layup condition or ply orientation to meet performance requirements. In this study, influences of stacking sequence and fiber orientation of glass fiber reinforced polymer (GFRP) circular tube on energy absorption performance were evaluated by axial quasi-static compression, drop weight tests and numerical simulation. Optimal ply angle and layup condition of composite tubes were obtained based on the finite element modeling and regression analysis. The optimization design result was validated by experiments. Drop weight tests results were analyzed and compared with quasi-static experimental results. Experimental and numerical results illustrate that proper increase of axial layups can improve the specific energy absorption of composite tubes.

Anomalous microstructure and excellent mechanical properties of Ni35Al21.67Cr21.67Fe21.67 high-entropy alloy with BCC and B2 structure

A quarternary Co-free Ni35Al21.67Cr21.67Fe21.67 high entropy alloy was designed and prepared by arc melting. The Ni35Al21.67Cr21.67Fe21.67 high entropy alloy (HEA) possesses disordered BCC phase and ordered BCC phase (B2). A “sunflower-like” microstructure was found in Ni35Al21.67Cr21.67Fe21.67 high entropy alloy. B2 phase forms the continuous matrix with the disordered BCC spherical particles (200 nm–300 nm) in ‘core’ region. In ‘petal’ region, striped B2 phases are inlaid in disordered BCC matrix. Moreover, the result of mechanical property test suggests that alloy presents outstanding compressive strength and excellent ductility with the microstructure of B2/BCC phase. The alloy showed an excellent comprehensive properties at room temperature (yield strength σ0.2 = 1471 MPa, compressive strength σb = 3541 MPa and compression rate ε = 40%) , which was superior to some traditional metallic materials. High strength was mainly attributed to high volume fraction of hard B2 phase matrix and B2 precipitations strengthening. Dislocations motion in disordered BCC matrix provided ductility for the alloy. The Ni35Al21.67Cr21.67Fe21.67 HEA has promising use in future structural applications.

A Rupture Limit Equation for Pre-Loaded Laminated Composite Plates

Fiber-reinforced polymer composites offer inherent advantages over traditional metallic materials in a number of different ways; however, these materials are also highly susceptible to impact damage. In this paper, we explore the response of FRP (fiber reinforced polymer) composites under impact conditions that could result in their rupture or catastrophic failure. The work performed was aimed at developing a general, data-driven equation for initially-stressed, flat, composite plates that would differentiate between impact conditions that would result in only a hole or crack and those which would cause catastrophic plate failure or rupture. If this equation were to be subsequently shown to also model the rupture/non-rupture behavior of, for example, composite overwrapped pressure vessels, then it could also be used to appropriately tailor the design parameters and/or operating conditions of such pressurized tanks.

Numerical evaluation of the performances of a multilayered

The improvements made in the field of the research of composite materials led to the wide usage of composite materials, which, nowadays, tend to replace traditional metallic materials in engineering applications. In this paper, the performances of a landing gear, subjected to dynamic loadings and made of a multilayered honeycomb composite material are evaluated in comparison with traditional metallic materials using numerical simulation. The obtained values of mechanical stress for the hybrid landing gear design are lower compared to those for a landing gear made entirely of aluminium. The use of the multilayered honeycomb composite material decreases the values of the stresses, for the given load case. Also, reduction of the mass of the landing gear improves flight dinamics and increases manoeuvrability.

Evolution of high temperature yield strength of AlCoCrFeNiTi high entropy alloys

Comparing with the properties of traditional metallic materials, high-entropy alloy has usually exhibited higher yield strength and hardness. Scientists and engineers are very keen to explore the possibilities to use high-entropy alloy in harsh environments with high temperature and pressure. So far, there have been very few reported studies on the yield strength of high-entropy alloys at elevated temperatures. In this study, AlCoCrFeNiTi high-entropy alloy was chosen to investigate its stress-strain relations under high temperature. Three different conditions of AlCoCrFeNiTi were studied (namely, as-cast, homogenized and hot deformed). The high temperature compression tests were conducted by using a Gleeble 3500 machine. AlCoCrFeNiTi material showed a high yield strength (159MPa) under 1100 ˚C with a strain rate of 1s-1. However, no visible cracks were observed on the surface of specimen after 46.6% of height reduction, which indicated that AlCoCrFeNiTi material possesses high yield strength and good formability.

Axial crushing of metal-composite hybrid tubes: experimental analysis

In the automotive sector, special attention is paid to the study of the behavior of the structural components that make the car bodies. The continuous demands on the weight saving imply the car bodies to be assembled with components made in different materials and using different manufacturing processes. Considering the making of the sacrificial structures aimed to the energy absorption, composite materials are increasingly used to replace conventional metal materials. However, the use of composites is accompanied with a change in the type of deformation obtained during the impact phenomenon. Usually, with the conventional metal materials, the crushing behavior is a progressive buckling whereas the composite materials are characterized by a brittle fracture. The combination of the traditional metal materials with the composite ones can represent a good solution to obtain high levels of performance.In this context, the structural performance of metal-composite hybrid tubes subjected to quasi-static axial crushing is experimentally evaluated in this work. The specimens, with circular cross section, were obtained with tubes made in a fully thermoplastic composite internally reinforced with aluminum tubes. The composite material used were made in polypropylene both for the matrix and for the reinforcing fibers. This material has a good axial absorption capacity but irregular behavior during crushing. The addition of a conventional material as reinforcement allowed to increase the absorption capacity by ensuring a more progressive and controlled crush. The analysis was carried out by evaluating, for various geometric configurations, different parameters (mean load, average stress, specific energy, efficiency). The results, discussed in the work, showed how the energy absorption performance of a hybrid structure are higher than the sum of the performance of the single materials.