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In the modern world, the ubiquity and critical importance of metallic materials are evident in everything from infrastructure and transportation to electronics and aerospace. Additive manufacturing (AM) of metals has revolutionized traditional production methods by enabling the creation of high-value components with topologically optimized complex geometries and functionalities. This review addresses the critical need for sophisticated physics-based models to investigate and optimize the AM processes of metals. We explore both melt-based and solid-state AM techniques, highlighting the current state-of-the-art modeling approaches. The purpose of this review is to evaluate existing models, identify their strengths and limitations, and suggest areas for future research to enhance the predictability and optimization of AM processes. By summarizing and comparing various modeling techniques, this review aims to provide a comprehensive understanding of the current research landscape. We focus on the pros and cons of different models, including their applicability to key elements and processes common to both melt-based and solid-state AM methods. Where multiple models exist for a single technique, a comparison is drawn to highlight their relative pros and cons. Concluding this review, we contemplate prospective advancements in sophisticated physics-based process modeling and strategies for their integration with models for structure-properties relations. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights: The development history and working mechanism of dual-ion batteries are reviewed, with an emphasis on the latest advancement in anode materials. A comprehensive and detailed summary of the synthesis strategies, structural optimization, performance characterization, and reaction principles of four types of anode materials for dual-ion batteries is presented. The current challenges of anode materials are highlighted, and the optimization strategies of advanced anode materials and battery systems are discussed, providing future research directions for the design of commercial dual-ion batteries. Distinct from "rocking-chair" lithium-ion batteries (LIBs), the unique anionic intercalation chemistry on the cathode side of dual-ion batteries (DIBs) endows them with intrinsic advantages of low cost, high voltage, and eco-friendly, which is attracting widespread attention, and is expected to achieve the next generation of large-scale energy storage applications. Although the electrochemical reactions on the anode side of DIBs are similar to that of LIBs, in fact, to match the rapid insertion kinetics of anions on the cathode side and consider the compatibility with electrolyte system which also serves as an active material, the anode materials play a very important role, and there is an urgent demand for rational structural design and performance optimization. A review and summarization of previous studies will facilitate the exploration and optimization of DIBs in the future. Here, we summarize the development process and working mechanism of DIBs and exhaustively categorize the latest research of DIBs anode materials and their applications in different battery systems. Moreover, the structural design, reaction mechanism and electrochemical performance of anode materials are briefly discussed. Finally, the fundamental challenges, potential strategies and perspectives are also put forward. It is hoped that this review could shed some light for researchers to explore more superior anode materials and advanced systems to further promote the development of DIBs. [ABSTRACT FROM AUTHOR]

The subject of hydrogen embrittlement seems to be more and more up-to-date and needed to be explored. World research teams working on this issue have not developed a clear method of preventing this process. The conclusion is that this issue should be approached individually, depending on the type of material, its structure and operating conditions. The problem will escalate in the near future as a result of the planned replacement of the traditional energy sources used so far with hydrogen energy. The paper presents the method of electrochemical hydrogenation, which reflects the conditions of galvanic coating of metallic materials used in the automotive industry. The aim of the research was to determine the influence of the time of hydrogenation on the properties and microstructure of austenitic steel. [ABSTRACT FROM AUTHOR]

Highlights The development history and working mechanism of dual-ion batteries are reviewed, with an emphasis on the latest advancement in anode materials. A comprehensive and detailed summary of the synthesis strategies, structural optimization, performance characterization, and reaction principles of four types of anode materials for dual-ion batteries is presented. The current challenges of anode materials are highlighted, and the optimization strategies of advanced anode materials and battery systems are discussed, providing future research directions for the design of commercial dual-ion batteries.

With the rapid advancement of modern society, the applications of materials are expanding across various fields. Among these, metallic materials have found wide use in industries such as biomedical, petrochemical, aerospace, orbital bridges, and marine vessels, making significant contributions to the manufacturing sector of the economy. As heavy machinery in industries undergoes rapid updates and iterations, there is a growing demand for metal fittings and structural components. However, these metal materials often experience common forms of failures, such as corrosion and wear, particularly at the surface, highlighting the crucial importance of surface protection. Material surface engineering presents a viable solution that effectively balances internal performance and investment costs, specifically addressing issues related to surface degradation and repair. By controlling the surface composition and structural design, it becomes possible to manage friction, corrosion, and mechanical properties of metal materials, resulting in notable advancements. One notable technique that has gained considerable traction in automotive engineering, aerospace, and other industries is tungsten inert gas (TIG) cladding. This technique offers unique composition properties, a pollution-free coating process, and a strong metallurgical bond between the alloy coating and the substrate. This review aims to provide a concise overview of TIG cladding, discussing parameter selection and the impact of different cladding powders on coating characteristics. Additionally, it summarizes the recent applications and research status of TIG cladding on titanium alloys, stainless steels, and other nonferrous alloys concerning their wear resistance, mechanical properties, and corrosion resistance. By exploring the advancements and findings in these areas, this review aims to contribute to the body of knowledge in the field of surface engineering and facilitate further research and development in TIG cladding technology. [ABSTRACT FROM AUTHOR]

The prediction of fatigue strength for metallic materials in a wide range of stress ratios is a crucial engineering challenge. To pursue a more accurate method, the dependence of fatigue strength on stress ratio for 35CrMo steel and other materials was investigated in detail. It was found that as the stress ratio increases, the damage mechanism changes, and the errors of the conventional models in predicting the fatigue strength increase. The reason is that those models fail to describe the fatigue damage evolution of metallic materials under some special conditions. Based on the variational fatigue damage, a new prediction method was proposed by introducing the damage parameter. Through the validation with fatigue strength covering a variety of metallic materials and loading conditions, the method exhibits higher universality. And then the corresponding parameter of the formula is further analyzed to elucidate the influences of various loading conditions on fatigue damage of materials. Highlights: The new method exhibits good generality and accuracy.The new method greatly improves the prediction efficiency.The optimized method can offer theoretical support to enhance fatigue properties. [ABSTRACT FROM AUTHOR]

The development of reliable and longevous infrastructures and structural components is the key for the implementation of a hydrogen economy that is currently enjoying unprecedented political and research momentum due to the globally strong demand for clean energy. This is, however, strongly impeded by the risk and concerns of hydrogen embrittlement (or hydrogen-induced degradation in mechanical properties) that generally exists in almost all metallic materials. Structural components and materials operated in the hydrogen production-transport-storage-usage chain can be subjected to a very wide range of temperature, environmental and loading scenarios, which will essentially trigger different hydrogen embrittlement responses and even different embrittling mechanisms. It is thus important to have a systematic assessment and discussion of hydrogen embrittlement behavior of different materials at different testing conditions, which is the focus of the presented review. Here we cover the typical materials (mainly metallic materials) that have been used or planned to be used in the fields of hydrogen energy. We first briefly summarize the current understanding of fundamental hydrogen embrittlement mechanisms in metallic materials and the research progress in recent years. Then we analyze and discuss the hydrogen -induced damage phenomenon in typical materials used in the field of high-pressure hydrogen transport and storage. In addition to room-temperature hydrogen embrittlement behavior, the hydrogen embrittlement phenomenon of some alloys at elevated and cryogenic temperatures is also reviewed, with the aim to provide some guidelines of material selection and design in developing fields such as hydrogen gas turbines and long-flight-duration hydrogen powered aircraft. Finally, the current challenges in the study of hydrogen embrittlement are identified and discussed to guide future research efforts.

Small-diameter, thin-walled pipes have applications in a wide range of industries including high-energy physics, heat transfer, nuclear, medical and communications. However, there are currently no standards that exist for permanently joining these components either via welding (melting the base material) or soldering. As such it is difficult to determine the likely performance of a thin-walled pipe connection. Porosity is largely inevitable in soldered joints and is a determining factor in the performance of a connection.This study focused on characterisation of failure initiation and propagation within soft soldered CuNi thin-walled pipe joints under cyclic internal pressure loading. A step-stress accelerated life testing regime (SSALT) was developed to simulate the loads the joints would experience over their operational lifetime, in a shorter timescale.10 soldered joints were studied in total, with varying levels of porosity within the soldered joints prior to testing. Pressurised Nitrogen gas was used to internally pressurise the samples, with cyclic loading between atmospheric conditions and a prescribed maximum pressure value.The results of the SSALT showed that the soldered samples experienced early failure through crack initiation and propagation through the solder. Cracks, or failures, were seen to initiate from existing voids, or porosity, within the soft-soldered joints.From this work, it can be concluded that the performance of soft-soldered joints under cyclic, internal pressure loading is strongly influenced by the presence of voids that are created during the manufacture of such soldered connections.

[Objective] Characterized by its abundant sources, green and low-carbon nature, and wide-ranging applications, hydrogen energy has become a significant strategic choice for accelerating energy transformation and upgrading, fostering new economic growth points, and achieving carbon neutrality goals. The hydrogen energy industry chain encompasses the production, storage, transportation, and utilization of hydrogen, with its storage and transportation being a crucial link connecting the upstream and downstream sectors of the chain. Hydrogen can be stored and transported in high-pressure gaseous, low-temperature liquid, and solid states. Among these, high-pressure gaseous storage and transportation have become dominant due to several advantages, including simple equipment structure, low cost, and high technological maturity. However, metallic materials used in hydrogen storage and transport equipment may suffer from high-pressure hydrogen embrittlement in such environments, characterized by reduced toughness and fracture toughness and accelerated fatigue crack propagation. This poses a significant threat to the safe operation of hydrogen storage and transport equipment. [Methods] The process of high-pressure hydrogen embrittlement is extremely complex, encompassing the physical adsorption of hydrogen on the material surface, chemical adsorption, as well as the dissolution, diffusion, and segregation of hydrogen atoms within the material. Numerous scholars have conducted in-depth studies on hydrogen embrittlement theories, forming various hypotheses, including hydrogen pressure theory, hydrogen-enhanced decohesion, hydrogen-enhanced localized plasticity, adsorption-induced dislocation emission, and hydrogen-enhanced strain-induced vacancy theory. However, these theories typically explain only certain aspects of hydrogen embrittlement and cannot independently account for all phenomena. In general, hydrogen embrittlement results from the combined effect of multiple mechanisms. To ensure safety, standards such as ASME VIII-3, JPEC-TD-0003, and T/CATSI 05003 mandate hydrogen compatibility testing for materials used in high-pressure hydrogen storage vessels. Hydrogen compatibility testing of materials involves directly testing the mechanical properties of materials in a high-pressure hydrogen environment. This includes tests like hydrogen embrittlement sensitivity, slow strain rate tensile, fatigue crack propagation rate, fatigue, and hydrogen-induced cracking stress intensity factor threshold tests. [Results] The hydrogen embrittlement sensitivity test is primarily used for the qualitative evaluation of a material's hydrogen embrittlement performance, while other tests provide basic data for the design of hydrogen storage and transport equipment. This testing must consider the impact of service conditions, environment, and stress on the results. Hydrogen compatibility testing apparatuses have high requirements for functionality and safety, including high-pressure hydrogen environment chambers, loading systems, displacement and gas supply systems, signal acquisition and processing systems, and safety assurance systems. Currently, only a few institutions have developed such testing equipment globally, resulting in scarce data on material hydrogen compatibility testing. In China, Zhejiang University has developed a 140-MPa high-pressure hydrogen environment material performance testing apparatus, meeting the testing requirements of various tests in GB/T 34542.2 and is at the forefront of testing capabilities worldwide. [Conclusions] Using the material 4130X as an example, fatigue crack growth rate tests were conducted in air and 50-MPa hydrogen. The results showed that high-pressure hydrogen significantly accelerated the fatigue crack propagation of 4130X. The acceleration level increased gradually with the extension of the crack and eventually stabilized. The fatigue crack growth rate in 50-MPa hydrogen was approximately 20 times that in air. [ABSTRACT FROM AUTHOR]

The prospect of improved quality of life and the increasingly younger age of patients benefiting from Total Hip Arthroplasty will soon lead to the landmark of 10 million interventions per year worldwide. More than 10% of these procedures lead to significant bone resorption, increasing the need for revision surgeries. Current research focuses on the development of hip implant designs to achieve a stiffness profile closer to the natural bone. Additive Manufacturing has emerged as a viable solution by offering promising results in the fabrication of implant architectures based on metallic cellular structures that have demonstrated their capacity to replicate bone behavior mechanically and biologically. Aiming to offer an up-to-date overview of titanium cellular structures in hip implants, for both acetabular and femoral components, produced by Additive Manufacturing, including its design intricacies and performance, this comprehensive review meticulously examines the historical development of hip implants, encompassing commercial solutions and innovative attempts. A broad view of the practical applications and transformative potential of hip implants incorporating cellular structures is presented, aiming to outline opportunities for innovation. [ABSTRACT FROM AUTHOR]

Cu–Cu soldering is realized under certain pressure and low temperature conditions by using a surface silver film to modify the copper microlayer structure, thus solving the problems of high thermal stress and signal delay aggravation caused by high temperature in the traditional reflow soldering process. The copper microlayer modified with silver film is obtained by electrodeposition. The surface substructure of the Cu microlayer is a nano cone-shaped protrusion. The diameter of the bottom of the cone is 500 nm∼1 μm, and the height of the cone is 1∼2 μm. The thickness of the silver film is about 320 nm, and the modification of the copper layer with silver film can effectively prevent the oxidation of the copper layer. Two silver-modified copper microlayers are placed in face-to-face contact as a soldering couple. A certain pressure and low temperature are applied to the contact area to realize the soldering and interconnection.The morphology of the soldered interface and the average shear strength of the soldered joints are analyzed by scanning electron microscopy, transmission electron microscopy and solder joint tester. It is found that under the optimal soldering parameters of soldering temperature 220 °C, soldering pressure 20 MPa and soldering time 20 min, the nano-conical projections of the Cu micrometer layer are inserted into each other to produce a physical blocking effect. The highly surface-meltable silver film effectively connects the surrounding copper layer as an intermediate buffer layer. The average shear strength of soldering joints is significantly increased. Heat treatment experiments have shown that the average shear strength can be effectively increased by heat treatment for an appropriate period of time. Prolonged exposure to heat has little effect on the average shear strength. With the special morphology of the copper microlayer structure and the nano-size effect of the silver layer, soldering can be done at low temperatures. The quality of the soldering interface is good and small soldering dimensions can be obtained.

Fused filament fabrication (FFF) is an extrusion-based additive manufacturing (AM) technology mostly used to produce thermoplastic parts. However, producing metallic or ceramic parts by FFF is also a sintered-based AM process. FFF for metallic parts can be divided into five steps: (1) raw material selection and feedstock mixture (including palletization), (2) filament production (extrusion), (3) production of AM components using the filament extrusion process, (4) debinding, and (5) sintering. These steps are interrelated, where the parameters interact with the others and have a key role in the integrity and quality of the final metallic parts. FFF can produce high-accuracy and complex metallic parts, potentially revolutionizing the manufacturing industry and taking AM components to a new level. In the FFF technology for metallic materials, material compatibility, production quality, and cost-effectiveness are the challenges to overcome to make it more competitive compared to other AM technologies, like the laser processes. This review provides a comprehensive overview of the recent developments in FFF for metallic materials, including the metals and binders used, the challenges faced, potential applications, and the impact of FFF on the manufacturing (prototyping and end parts), design freedom, customization, sustainability, supply chain, among others. [ABSTRACT FROM AUTHOR]

In this study, the role of a scan strategy in the fabrication of a single crystal (SX) structure of face-centered cubic (fcc) pure Ni using a flat-top laser profile by a laser powder bed fusion (LPBF) process was investigated. A flat-top laser with a uniform heat intensity across the beam profile was employed to fabricate the SX structure with a <001> texture parallel to the build direction (║BD). A meander scan strategy with an XY–90° scan rotation was required to achieve the flat-top-derived SX structure. The meander scanning strategy promoted the epitaxial <001> fcc growth along the direction ║BD, leading to the <001>║BD texture formation. Meanwhile, the XY–90° scan rotation induced the epitaxial growth of <001> fcc phase on the hatch direction (HD)–scan direction (SD) plane in the direction deviated by approximately 45° relative to the SD. This 45° deviation relative to the SD occurred to accommodate the beam movement and the circular beam geometry on the HD – SD plane, resulting in the preferred configurations of <011>║SD and HD. Thus, this paper reports the importance of meander scanning with a 90° scan-rotation strategy to yield a flat-top-LPBF-derived SX structure with <001>║BD and <011>║SD and HD textures. [ABSTRACT FROM AUTHOR]

In industrial sectors like medical and automotive engineering, the demand for metal components with a high function integration brings conventional production technologies to their limits. This motivates research on innovative processes, which can meet the present requirements on fabricated parts and consequently also the demands on the applied manufacturing process. Part-sided, a high strength, narrow dimensional tolerances and a large functionality is often desired. In addition, an economical component production calls for processes with high material utilization as well as the achievement of short cycle times. The process class of sheet-bulk metal forming, characterized by the application of bulk forming operations on sheet metal, offers the potential to meet these requirements. Currently, sheet-bulk metal forming is mainly used for the fabrication of components with functional elements of macroscopic size. However, microscopic elements and micro-textured surfaces are of high interest for applications in prosthetics and automotive engineering. The objective of this study is therefore to develop an application-oriented method for the design, production and testing of 16MnCr5 metal components, manufactured by a combined process of sheet-bulk metal forming, creating a defined microstructure on the surface. Since the selection of a suitable texture layout and geometry is crucial for tribological optimization, these are designed for their application using numerical elastohydrodynamic lubricant simulations. The contact conditions occurring in the application are modelled as realistically as possible so that texture designs suitable for production can subsequently be compared in test bench trials. It is shown that the tappets produced by forming technology can be efficiently investigated with the test rig presented. [ABSTRACT FROM AUTHOR]

This research paper looks at the surface quality acquired during the laser cutting of metallic materials, with an emphasis on S235JR. We conducted studies on a FiberMak Momentum Gen-2 laser cutting machine to determine the effect of process settings on surface quality. We varied laser beam power and feed rate while keeping other parameters constant, such as nozzle diameter, CO2 pressure, and focal length. Results showed that surface quality is significantly influenced by these parameters. We identified two distinct zones on the cut surface: one with favorable roughness and another with less favorable roughness. Overall, increasing laser beam power led to improved surface quality, while increasing the feed rate resulted in a degradation of the surface. By analyzing the experimental data, we identified an optimal parameter combination for achieving high surface quality. These discoveries have practical applications in business and help to a theoretical knowledge of the laser cutting process. [ABSTRACT FROM AUTHOR]

The need for a more sustainable and accessible source of energy is increasing as human society advances. The use of different metallic materials and their challenges in current and future energy sectors are the primary focus of the first part of this review. Cryogenic treatment (CT), one of the possible solutions for an environmentally friendly, sustainable, and cost-effective technology for tailoring the properties of these materials, is the focus of second part of the review. CT was found to have great potential for the improvement of the properties of metallic materials and the extension of their service life. The focus of the review is on selected surface properties and corrosion resistance, which are under-researched and have great potential for future research and application of CT in the energy sector. Most research reports that CT improves corrosion resistance by up to 90%. This is based on the unique oxide formation that can provide corrosion protection and extend the life of metallic materials by up to three times. However, more research should be conducted on the surface resistance and corrosion resistance of metallic materials in future studies to provide standards for the application of CT in the energy sector. [ABSTRACT FROM AUTHOR]

A theoretical study of the phenomenon of the superplasticity of metallic materials is carried out. Numerical calculations are performed on the basis of a two-level finite-element model of an elastic–plastic medium. The plastic properties of the deformable-medium element, at which deformation by uniaxial tension in the superplasticity mode occurs, are found. It is shown that depending on the shape of the stress–strain curve (σ–ε) of the medium element, various types of plastic-flow localizations are observed at the macroscale level. The nonmonotonic dependence σ–ε of a deformable-medium element with a single maximum is determined as the condition for the appearance of a stable necking. In the case when the dependence σ–ε, which is characterized by the hardening of the elementary volumes, has two maxima, a propagating (running) neck is observed, then a second (counter) neck appears, while further tension leads to the appearance of a third stable neck in which fracture occurs. In the case of a more complex oscillating shape of the σ–ε curve, multiple propagating necks are observed. The movement of multiple necks propagating along the sample leads, ultimately, to a uniform pattern of deformation and makes it possible to achieve the strain values observed in the superplasticity mode. [ABSTRACT FROM AUTHOR]

Metallic cellular solids, made of biocompatible alloys like titanium, stainless steel, or cobalt-chromium, have gained attention for their mechanical strength, reliability, and biocompatibility. These three-dimensional structures provide support and aid tissue regeneration in orthopedic implants, cardiovascular stents, and other tissue engineering cellular solids. The design and material chemistry of metallic cellular solids play crucial roles in their performance: factors such as porosity, pore size, and surface roughness influence nutrient transport, cell attachment, and mechanical stability, while their microstructure imparts strength, durability and flexibility. Various techniques, including additive manufacturing and conventional fabrication methods, are utilized for producing metallic biomedical cellular solids, each offering distinct advantages and drawbacks that must be considered for optimal design and manufacturing. The combination of mechanical properties and biocompatibility makes metallic cellular solids superior to their ceramic and polymeric counterparts in most load bearing applications, in particular under cyclic fatigue conditions, and more in general in application that require long term reliability. Although challenges remain, such as reducing the production times and the associated costs or increasing the array of available materials, metallic cellular solids showed excellent long-term reliability, with high survival rates even in long term follow-ups.

ABSTRACTIn this study, the role of a scan strategy in the fabrication of a single crystal (SX) structure of face-centered cubic (fcc) pure Ni using a flat-top laser profile by a laser powder bed fusion (LPBF) process was investigated. A flat-top laser with a uniform heat intensity across the beam profile was employed to fabricate the SX structure with a texture parallel to the build direction (║BD). A meander scan strategy with an XY–90° scan rotation was required to achieve the flat-top-derived SX structure. The meander scanning strategy promoted the epitaxial fcc growth along the direction ║BD, leading to the ║BD texture formation. Meanwhile, the XY–90° scan rotation induced the epitaxial growth of fcc phase on the hatch direction (HD)–scan direction (SD) plane in the direction deviated by approximately 45° relative to the SD. This 45° deviation relative to the SD occurred to accommodate the beam movement and the circular beam geometry on the HD – SD plane, resulting in the preferred configurations of ║SD and HD. Thus, this paper reports the importance of meander scanning with a 90° scan-rotation strategy to yield a flat-top-LPBF-derived SX structure with ║BD and ║SD and HD textures.

A methodology for quantifying the variation of the static friction coefficient µ due to different site surface conditions, and for metallic materials with hardness ratios ρ = 0.5 - 2, is proposed. ρ is defined as the ratio between the material hardness and the A36 steel hardness. For each material, 7 coupons were considered in the site conditions "clean", "bought", "polished" and "corroded". Results show if surfaces are kept as "bought", µ may increase or decrease up to 20%, if surfaces are polished, µ may increases up to 37%, and if surfaces are corroded µ may increases up to 410% when considering corrosion rates of 90 - 670 µm/year. These increments or reductions were calculated respect to the site condition "clean". Results also show for "clean" surfaces and for ρ = 1.7, µ is dependent on ρ, for ρ > 1.7, µ is approximately constant. A model for quantifying variations of µ for the considered site surface conditions was proposed. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement (HE) is characterized by the sudden loss of a material's mechanical property due to the premature failure induced by the ingress of H atoms and various H‐materials interactions. This phenomenon threatens almost all the metallic materials that brings an abrupt halt to some of the pending infrastructures needed for a H economy. The development of microstructure design strategies to mitigate HE is challenging, as the fundamental mechanisms for HE process are still not well understood. Nevertheless, some progresses in this field have been made in recent years. Here, we provide an overview on established microstructural approaches to mitigate HE in metallic materials. These methods include second‐phase trapping, grain refinement, grain boundary engineering, solute segregation and heterogeneity, and surface treatment. Their effectiveness and materials applicability are compared. The operating mechanisms, advantages, and limitations of these approaches are also discussed to guide their future development and successful industrial application. Highlights: H embrittlement threatens the development of infrastructures needed for a H economy.Five microstructure design strategies to mitigate H embrittlement are reviewed.Effectiveness, advantages, and limitations of these H‐tolerant approaches are discussed. [ABSTRACT FROM AUTHOR]

The topic of loading frequency effect on fatigue behavior is in close relation to high‐cycle fatigue (HCF) and very‐HCF (VHCF) research. The conventional loading frequency in fatigue tests is normally between 10 and 100 Hz. In order to accelerate testing process, researchers have developed ultrasonic vibration device with a very high frequency, for example, 20 kHz, to perform VHCF tests. Thus, a question has always been asked: Does loading frequency affect the fatigue behavior of tested material? It is obvious that the answer is yes because the remarkable difference in strain rate with respect to different loading frequencies may cause the change of fatigue mechanism and the related fatigue performance. The subsequent question is how is the effect of loading frequency on fatigue behavior? This paper attempts to address such questions by two cases of experimental investigations. Moreover, typical results in literature are quoted for the further discussion of this issue. Highlights: Literature review of loading frequency effect on fatigue performance of materials.Ultrasonic frequency resulting in higher fatigue strength for low‐strength materials.Loading frequency effect diminishing for high‐strength materials.Frequency effect in relation to material's lattice type and specimen temperature rise. [ABSTRACT FROM AUTHOR]

This overview article discusses the Equal Channel Angular Pressing (ECAP) processing of different metallic materials. Particular emphasis is given to the microstructural evolution from the coarse grain (CG) to the ultrafine-grained (UFG) states throughout the electron backscattering diffraction (EBSD) technique. Iron-based alloys, such as duplex and 1020 low-carbon steels reached higher hardening with a lower deformation and lower non-ultrafine average grain sizes than the ultrafine pure iron condition due to fast grain fragmentation, i.e., more geometrically necessary dislocation (GND) grouping. Moreover, due to the magnesium adhesion, copper alloys reached superior mechanical properties compared to pure copper even when the initial grain size for as-cast alloys was over 1000 µm. On the other hand, low melting temperature (TMP) materials processed at 250°C, like the ZK60 magnesium and AA6082 aluminum alloys (i.e., homologous temperatures (TH) of 0.38TMP and 0.37TMP, respectively), showed grain refinement without reaching the ultrafine regime and mechanical softening due to the static and dynamic recrystallization phenomena. CP titanium also displayed heterogeneous grain sizes with average values of above 1 µm after four ECAP passes for temperatures ranging between 150°C and 400°C (TH between 0.09TMP = 0.24TMP). The evolution of the GNDs suggested that the initial deformation stages of severe plastic deformation (SPD) by ECAP produced the most notorious density increments from 1012m-2 to 1014m-2, which level up at high deformations (more than four ECAP passes) around 10141015m-2, explaining the fast and slow grain size reduction rates, respectively. The ECAP processing on different metallic material systems showed a larger grain fragmentation capacity in high melting points and alloyed materials, giving rise to steep yield strength increases and low ductility. The low ductility and grain size saturation correspond to a low capacity to create new grain boundaries manifested by the GNDs saturation in the UFG range. [ABSTRACT FROM AUTHOR]

This paper gives an overview about some mechanical properties of materials processed by surface severe plastic deformation (SSPD) techniques. SSPD processed materials are classified in terms of characteristics, and main generated parameters that determine the output properties of materials are presented. The influences of SSPD on mechanical properties of materials are then reviewed. Furthermore, the roles played by some parameters such as gradient microstructure, nanostructured layer, compressive residual stress (CRS) and surface integrity are highlighted by discussing their contributions. Finally, some conclusions are drawn and possible prospects for future research are underlined. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Additive friction stir deposition (AFSD) is a relatively new additive manufacturing technique to fabricate parts in solid state below the melting temperature. Due to the solid-state nature, AFSD benefits from lower residual stresses as well as significantly lower susceptibility to porosity, hot-cracking, and other defects compared to conventional fusion-based metallic additive manufacturing. These unique features make AFSD a promising alternative to conventional forging for fabricating large structures for aerospace, naval, nuclear, and automotive applications. This review comprehensively summarizes the advances in AFSD, as well as the microstructure and properties of the final part. Given the rapidly growing research in AFSD, we focus on fundamental questions and issues, with a particular emphasis on the underlying relationship between AFSD-based processing, microstructure, and mechanical properties. The implications of the experimental and modeling research in AFSD will be discussed in detail. Unlike the columnar structure in fusion-based additive manufacturing, fully dense material with a fine, fully-equiaxed microstructure can be fabricated in AFSD. The as-wrought structure brings the as-printed parts with comparable properties to wrought parts. The fundamental difference between AFSD and fusion-based metallic additive manufacturing will be summarized. Furthermore, the existing challenges and possible future research directions are explored.

Advanced experimental and numerical approaches are being developed to capture the localization of plasticity at the nanometer scale as a function of the multiscale and heterogeneous microstructure present in metallic materials. These innovative approaches promise new avenues to understand microstructural effects on mechanical properties, accelerate alloy design, and enable more accurate mechanical property prediction. This article provides an overview of emerging approaches with a focus on the localization of plasticity by crystallographic slip. New insights into the mechanisms and mechanics of strain localization are addressed. The consequences of the localization of plasticity by deformation slip for mechanical properties of metallic materials are also detailed. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have gained interest in recent years for anticorrosion applications owing to their inimitable structures and excellent properties. As a prominent subclass of MOFs, zeolite imidazolate frameworks (ZIFs) exhibited hydrophobicity, corrosion inhibition, and positive water stability, making them frequently appear in the field of metallic anticorrosion. This review presents the establishment and development of a theoretical model for superhydrophobicity, followed by the reported applications of different kinds of ZIFs in the field of metallic anticorrosion with particular emphasis on ZIF-8, which is the most extensively researched structure among ZIFs. In addition, the applications of superhydrophobic coatings in many aspects other than anticorrosion are also summarized. Finally, the existing challenging problems and future development trends of this kind of coating are discussed. It is hoped that this review will contribute to further development in the field of superhydrophobic anticorrosion coatings for metallic materials. [ABSTRACT FROM AUTHOR]

For the last few decades, the rapid growth of Additive Manufacturing (AM) technologies has been seeable. It is expected to keep maturing continuously due to its advantages compared to conventional manufacturing technologies: flexibility, reliability, energy consumption, and material efficiency. This research article addresses the development and production of a stapler using the Material Extrusion AM process. It is intended to show the development steps to redesign an everyday stapler, into an added-value tool, from the selection and fixture of the CAD model and generative design through Fusion 360 to its optimization on nTopology, simulation, and plot of the part in Eiger.

Small-diameter, thin-walled pipes have applications in a wide range of industries including high-energy physics, heat transfer, nuclear, medical and communications. There are no standards that exist for welds less than 0.5 mm in width, and as such it is difficult to determine the likely performance of a thin-walled pipe weld. Porosity is largely inevitable in fusion welded joints and is a determining factor in the performance of a connection.This study focused on characterisation of the evolution of strains in soldered welds less than 0.5 mm in width, by incrementally tensile loading samples and studying them in-situ with Synchrotron X-Ray Computed Tomography and X-Ray Diffraction. Two sample geometries were studied, and porosity defects were present in both, although the levels of porosity size, number and area varied dramatically between the two samples.Lattice strain interpretation showed that crack propagation for such samples is not driven by porosity but that crack evolution occurs at the same location and load levels irrespective of the presence of pores. Residual stresses of up to 0.3% from the fusion welding process were seen in both samples and appear to have a greater impact on locations of failure than porosity. Porosity does cause differences in strains across directions, however high strains alone did not appear to cause premature failure. Hence, efforts to improve weld strength should in future focus more on reducing residual stresses than reducing porosity.

Martensitic stainless steels are indispensable alloys in various high stress and temperature applications such as plastic injection molds and components in steam generators. Subtractive manufacturing methods used to fabricate these parts, however, limits its functionality and performance due to design constraint of cooling channels. This limitation can be resolved by means of additive manufacturing while ensuring that acceptable high-temperature properties can be achieved. In this work, the mechanical behavior of additively manufactured 420 stainless steel (AM420SS) is explored through material constitutive modeling to determine the mathematical model that best describes its flow stress in extreme conditions. This is accomplished by subjecting the samples to hot compression under the strain rates of 0.1–1.0 s ^−1 , and temperatures between 973–1423 K (700 °C–1150 °C) via Gleeble thermomechanical test. The experimental data were used to generate the predictive flow stress curves of constitutive models which includes Johnson-Cook, Zerilli-Armstrong, Zener-Hollomon, and Hensel-Spittel equations. Results showed that Zener-Hollomon and Hensel-Spittel models are the most accurate material constitutive equations with relatively high R values of 0.986 and 0.976, and low average absolute relative error values of 6.96% and 7.69%, respectively. The material constants derived from these models can be applied in finite element analysis simulations to assess the performance of using AM420SS parts at high temperature and strain conditions.

With the rising demand for nuclear energy, the storage/transportation of radioactive nuclear by-products are critical safety issues for humans and the environment. These by-products are closely related to various nuclear radiations. In particular, neutron radiation requires specific protection by neutron shielding materials due to its high penetrating ability to cause irradiation damage. Herein, a basic overview of neutron shielding is presented. Since gadolinium (Gd) has the largest thermal neutron capture cross-section among various neutron absorbing elements, it is an ideal neutron absorber for shielding applications. In the last two decades, there have been many newly developed Gd-containing (i.e., inorganic nonmetallic-based, polymer-based, and metallic-based) shielding materials developed to attenuate and absorb the incident neutrons. On this basis, we present a comprehensive review of the design, processing methods, microstructure characteristics, mechanical properties, and neutron shielding performance of these materials in each category. Furthermore, current challenges for the development and application of shielding materials are discussed. Finally, the potential research directions are highlighted in this rapidly developing field. [ABSTRACT FROM AUTHOR]

This work attempts to develop a theoretical model in combination with the representative volume element (RVE) theory for realizing rapid fatigue limit prediction. Within the thermodynamic framework, it is believed that two components, namely anelastic and microplastic behaviors, which correspond to recoverable and non-recoverable microstructural motions, contribute to temperature variation during high-cycle fatigue. Based on this, the constitutive equation of the response relationship between the temperature rise evolution and the stress amplitude of metallic materials can be deduced in combination with the heat balance equation. Meanwhile, a determination approach for the thermographic experimental data for accurate fatigue limit estimation is developed by combining it with a statistical method. Finally, the experimental data of metallic specimens and welded joints were utilized to validate the proposed model, and the results demonstrated great agreement between experimental and predicted data. [ABSTRACT FROM AUTHOR]

The review starts by highlighting the significance of nuclear power plants in the contemporary world, especially its indispensable role in the global efforts to reduce CO2 emissions. Then, it describes the impact of irradiation on the microstructure and mechanical properties of reactor structural materials. The main part provides the reader with a thorough overview of crystal plasticity models developed to address the irradiation effects so far. All three groups of the most important materials are included. Namely, the Zr alloys used for fuel cladding, austenitic stainless steels used for reactor internals, and ferritic steels used for reactor pressure vessels. Other materials, especially those considered for construction of future fission and fusion nuclear power plants, are also mentioned. The review also pays special attention to ion implantation and instrumented nanoindentation which are common ways to substitute costly and time-consuming neutron irradiation campaigns. [ABSTRACT FROM AUTHOR]

Since the first paper on the fatigue of metallic materials by J. Albert in 1837, tremendous numbers of papers have been published in various journals by many researchers all over the world. Based on such a long history, several papers on the very high cycle fatigue (VHCF) in the life‐time longer than 107 cycles had appeared in some journals during the period of 1980's. One characteristic finding in these works is the fact that the metallic material can fail even at the stress level lower than the conventional fatigue limit. This fact means that the conventional fatigue design of mechanical structures cannot give the safety of the practical products in the very high cycle regime. Due to this fact, fatigue properties of structural materials in very long life regime has become an important subject; and a lot of studies have been carried out, and many important results have been accumulated until now. Typical aspects on VHCF property are summarized as follows: (1) the fatigue crack tends to occur around the interior inclusion, (2) fine granular area (FGA) is formed around such an inclusion, and (3) duplex S–N characteristics appear in the VHCF regime. In this paper, a brief historical review together with the future prospect on the very high cycle fatigue of metallic materials is attempted for the sake of reference to facilitate the research in this area. Highlights: Historical review and future prospect for researches on metal fatigue.Progress of researches on very high cycle fatigue of metallic materials.Review of interior crack initiation and growth mechanisms around inclusion.Quantitative formulation of interior crack growth around inclusion. [ABSTRACT FROM AUTHOR]

The reactive metal-support interaction in the Cu-In2O3 system and its implications on the CO2 selectivity in methanol steam reforming (MSR) have been assessed using nanosized Cu particles on a powdered cubic In2O3 support. Reduction in hydrogen at 300 °C resulted in the formation of metallic Cu particles on In2O3. This system already represents a highly CO2-selective MSR catalyst with ~93% selectivity, but only 56% methanol conversion and a maximum H2 formation rate of 1.3 µmol gCu -1 s-1. After reduction at 400 °C, the system enters an In2O3-supported intermetallic compound state with Cu2In as the majority phase. Cu2In exhibits markedly different self-activating properties at equally pronounced CO2 selectivities between 92% and 94%. A methanol conversion improvement from roughly 64% to 84% accompanied by an increase in the maximum hydrogen formation rate from 1.8 to 3.8 µmol gCu -1 s-1 has been observed from the first to the fourth consecutive runs. The presented results directly show the prospective properties of a new class of Cu-based intermetallic materials, beneficially combining the MSR properties of the catalyst's constituents Cu and In2O3. In essence, the results also open up the pathway to in-depth development of potentially CO2-selective bulk intermetallic Cu-In compounds with well-defined stoichiometry in MSR.

Additive manufacturing (AM), or 3D printing, is an emerging technology that “adds” materials up and constructs products through a layer-by-layer procedure. Laser powder bed fusion (LPBF) is a powder-bed-based AM technology that can fabricate a large variety of metallic materials with excellent quality and accuracy. However, various defects such as porosity, cracks, and incursions can be generated during the printing process. As the most universal and a near-inevitable defect, porosity plays a substantial role in determining the mechanical performance of as-printed products. This work presents a comprehensive review of literatures that focused on the porosity in LPBF printed metals. The formation mechanisms, evaluation methods, effects on mechanical performance with corresponding models, and controlling methods of porosity have been illustrated and discussed in-depth. Achievements in four representative metals, namely Ti−6Al−4V, 316L, Inconel 718, and AlSi10Mg, have been critically reviewed with a statistical analysis on the correlation between porosity fraction and tensile properties. Ductility has been determined as the most sensitive property to porosity among several key tensile properties. This review also provides potential directions and opportunities to address the current porosity-related challenges.

Elastic modulus plays a key role in the application of porous metallic materials. However, to the best of our knowledge, few attempts have been made to model the simultaneous dependence of elastic modulus on temperature and porosity for metallic materials. The present article contributes to a rational temperature-porosity-dependent elastic modulus model for metallic materials with all parameters having definite physical significance. The model can well predict the elastic moduli of porous metallic materials, from extremely low temperature to ultrahigh temperature, and from dense material to about 0.9 porosity, with reference to an easy-to-access elastic modulus. In a special case, when intrinsic elastic modulus [M] = 2 and critical porosity P C = 1, a phenomenological parameter-free predictive model can be obtained. The model can be applied when the matrix Poisson ratio is 0.1 < v < 0.4 for Young’s modulus and 0.17 < v < 0.27 for shear modulus, which covers most metallic porous materials.

The harmonic structure is a recently introduced concept paving the way for engineering metallic materials to achieve excellent mechanical performance. They consist of soft coarse-grained regions (Core) that are three-dimensionally surrounded by a connected network of hard ultra-fine grained regions (Shell). The interaction in these Core–Shell regions produces a synergistic effect, during plastic deformation, leading to superior mechanical properties that are extremely important in practical applications. The current review paper is aimed at providing a critical assessment on this novel concept of microstructure design. It also involves the identification and critical discussion of key issues which deserve additional studies.