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Soil-fluid retention (SFR) is considered a fundamental unsaturated property with a wide application from transient flow analysis, and strength prediction to constitutive modeling. Previous research has led to a consensus that soil microstructure can significantly affect retention properties. Furthermore, the soil microstructure is subject to changes due to variations in the sampling method and pore fluid chemistry. Therefore, this study aims to explore the influence of multiple factors, including sample preparation technique, dissolved salt concentration and cation type, on soil-fluid retention and volumetric behavior in a systematic manner. The results of tests conducted by employing the axis translation and filter paper methods are interpreted in detail based on some complementary scanning electron microscopy and micro-CT scan experiments. Furthermore, the repeatability of the test results is validated through some control tests. The results reveal a higher retention capacity for reconstituted samples compared with the compacted ones independent of the solute concentration. In contrast, both the SFR and shrinkage are suppressed by the addition of sodium chloride to the pore fluid independent of the sample preparation method. It is also found that the SFR capability of potassium cation is less than that of sodium cation at the same concentration. The SFRs are quantified and compared in terms of air entry/air expulsion suction, hydraulic hysteresis and desorption/adsorption rates. The interpretation of the results in light of the diffuse double-layer theory is supported by microstructural observation and provides insights into the SFR of lean clays exposed to saline environments with different types of salt species. [ABSTRACT FROM AUTHOR]

Paper is susceptible to chemical degradation through hydrolysis and oxidation, resulting in embrittlement and failure. Understanding the embrittlement process is important to ensure the preservation and longevity of historical paper-based documents. However, the complex and architectured paper microstructure is a major challenge for fully understanding this process. Two papers with different microstructures were artificially aged under hydrolytic and oxidative exposure conditions, and the consequences of ageing were studied. The fibre embrittlement, the fibre–fibre bonds deterioration, and the evolution of paper microstructure upon ageing are evaluated through macroscopic and localised mechanical tests, as well as through morphological observations at the microscopic scale. It was concluded, from the different tests in the two principal orientations of the paper, that fibre embrittlement plays a more significant role in the embrittlement process than fibre–fibre bonds deterioration. Specifically, the cellulose chain scissions led to fibre embrittlement, irrespective of the oxidative or hydrolytic nature of the chemical degradation mechanism. Furthermore, we identify a critical degree of polymerisation for cellulose (DPc ~ 750) below which the evolution of mechanical properties accelerates significantly, regardless of the type of mechanical testing performed. Fibre analysis suggests that the decline in fibre resistance results in fractures occurring under stress at weak points of the fibres, such as kinks or twists. [ABSTRACT FROM AUTHOR]

Moisture sorption and diffusion processes of plant fiber materials have a significant impact on their properties and product quality in healthcare, food production, cigarette processing, textile field, and papermaking industry. The infiltration process affects the rate of water sorption and processing of flavoring liquids, and exploring its mechanisms can optimize the production process. Here, multi-scale imaging approach was employed to identify the heterogeneous structure of plant leaves and the impact of multilevel fiber structure and pore channels on water adsorption. The dissipative changes and mechanisms of water adsorption, osmotic diffusion, and hygroscopic swelling in plant leaves were illustrated. Furthermore, the effects of temperature and water activity on water diffusion under different environmental conditions are determined through a comparison of adsorption equilibrium and diffusion electrochemical impedance analysis (EIS), with a focus on the water-blocking effect of the waxy layer interface. This work investigated the correlation between the impedance change in water transport and the natural layered water-blocking polymer film structure and multi-level pore structure. This study sheds new light on biological multi-scale fiber materials and these findings are important reference value for manufacturing processes to improve the moisturizing properties of functional plant fibers in the field of food preservation. [ABSTRACT FROM AUTHOR]

Abstract—This paper studies the chemical composition stability of modified 1 mol % CaO ceramic composites which contain 50 mol % Al2O3 and 50 mol % [12Ce–TZP] or 50 mol % [3Yb–TZP] and are produced from powders synthesized by a hydrolytic sol-gel method. It is shown that the content of dangerous elements, such as As, Be, Cd, Cr, Pb, and Sb, in the new composites is below the maximum allowable limits. In addition, this paper establishes the high stability in the chemical composition of the composites after a long presence in a media that simulates the conditions of the body. The mass loss for Al is no more than 5 × 10–4 wt %; for Zr, it is no more than 1 × 10–4 wt %. [ABSTRACT FROM AUTHOR]

This review paper offers a comprehensive analysis of the cold metal transfer (CMT) welding process in the context of similar metals and alloys. With a focus on recent advancements and key research contributions, the paper synthesizes a wealth of information to provide an understanding of the technique's applicability and potential in welding similar metals and alloys. By delving into the intricate interplay of process parameters, such as welding current, wire feed speed and shielding gas composition, the paper elucidates their influence on critical aspects of weld quality, including bead morphology, microstructure, and mechanical properties. In summation, this review consolidates the collective knowledge surrounding CMT welding of similar metals and alloys, providing researchers, practitioners, and industries with a comprehensive resource to navigate the intricacies of this technique. As the industrial landscape seeks to elevate welding standards, minimize post-weld processing, and optimize resource utilization, the insights presented in this review pave the way for the continued evolution and widespread adoption of CMT welding in the field of similar metals and alloys. [ABSTRACT FROM AUTHOR]

Medium- and high-entropy alloys (MEAs/HEAs) or multi-principal element alloys are a new class of promising alloys with wide application possibilities in several industries like nuclear, offshore, liquefied natural gas, and transportation, among others. The development of these revolutionary alloys comes with the need to separately unravel their weldability as the microstructure and the welding-induced thermal responses of the single, dual, and multi-phase HEAs differ. Detailed knowledge of the weldability of MEAs/HEAs is still at the early stage and remains a useful link between the developed MEAs/HEAs and their full-scale industrial manufacturing applications. The intense heat input of fusion welding techniques easily introduces different or combined challenges such as elemental segregation, inhomogeneous phase transformation, solidification cracking, and coarsened structure to the weld metals of HEAs. As a result, this paper provides a state-of-the-art review of the low heat-input or solid-state welding and friction stir processing of MEAs/HEAs. The welding section covers explosive and friction stir welding processes of HEAs. Insights into the future research areas that can further progress the scientific understanding and weldability of MEAs/HEAs are briefly explicated in this paper. [ABSTRACT FROM AUTHOR]

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In pulsed electrochemical machining (PECM), it is difficult to control machining stability and surface quality numerous due to the interrelated variables with highly nonlinear and complex characteristics. Thus, how to determine the optimal process parameters to ensure optimal machining performance became a hot research. In this paper, we investigate the recurrence behavior of Ti–48Al–2Cr–2Nb alloy in PECM by recurrence plots and the quantitative analysis. Besides, the Technique for Order Preference by Similarity to Ideal Solution with Criteria Importance through Intercriteria Correlation (CRITIC-TOPSIS) is employed to determine the optimal process parameters for PECM. The results demonstrate that the recurrence plots exhibit periodic characteristics at the macro level, and effectively identify current density changes in different dissolution stages of the alloy at the micro level. Each pulse stage exhibits an inherent oscillation frequency, and the recurrence plots display a similar block structure with evident fractal features. The optimal result show that the optimal process parameters for the potential, the duty cycle, electrolyte pressure and the feed velocity is 16 V, 40%, 0.4 MPa and 0.9 mm/min, respectively. After optimization, the machining stability and the surface morphology uniformity improves by 29.82 and 72.78%, respectively, and the surface roughness decreases by 24.09%, providing a basis for establishing the quantitative relationship between the machining stability and the surface roughness. [ABSTRACT FROM AUTHOR]

Digital twin, a core technology for intelligent manufacturing, has gained extensive research interest. The current research was mainly focused on digital twin based on design models representing ideal geometric features and behaviors at macroscopic scales, which is challenging to accurately represent accuracy and performance. However, a numerical representation is essential for precision microstructures whose accuracy and performance are difficult to measure. The concept of a digital twin for an accurate representation, proposed in 2015, is still in the conceptual stage without a clear construction method. Therefore, the goal of accurate representation has not been achieved. This paper defines the concept and connotation of an accuracy and performance-oriented accurate digital twin model and establishes its architecture in two levels: geometric and physical. First, a geometric digital twin model is constructed by the contact surfaces distributed error modeling and virtual assembly with nonuniform contact states. Then, based on this, a physical digital twin model is constructed by considering the linear and nonlinear response of the structural internal physical properties to the external environment and time to characterize the accuracy and performance variation. Finally, the models are evaluated. The method is validated on microtarget assembly. The estimated values of surface modeling, center offset, and stress prediction accuracy are 94.22%, 89.3%, and 83.27%. This paper provides a modeling methodology for the digital twin research to accurately represent accuracy and performance, which is critical for product quality improvements in intelligent manufacturing. Research results can be extended to larger-scale precision structures for performance prediction and optimization. [ABSTRACT FROM AUTHOR]

Commercially pure titanium (CP-Ti) plates were friction stir welded (FSWed) using a welding tool with a tungsten carbide (WC) pin. The bead-on-plate technique was applied to reduce the effects of welding defects, such as incomplete penetration. Whereas many papers have reported on creep studies of CP-Ti as well as on FSW of CP-Ti, no paper has investigated the creep behavior of a CP-Ti FSW'ed joint. Consequently, the current study focuses on this topic. The current paper, which is part of a broader research project, focuses on the metallurgical processes occurring during the creep of a FSW'ed CP-Ti joint at the temperature range of 550-650 °C. Based on the current study and previous results obtained by the authors, it can be concluded that the weld is not the weakest link. In every case, necking and creep fracture occurred in the parent material (PM), rather than either the thermomechanically affected zone (TMAZ) or the stir zone (SZ), indicating that both zones are more creep-resistant than the parent material. Fractography showed that the fracture surface was typical of creep fracture and that the fracture mechanism was microvoid coalescence and also ruled out any preexisting defect. TEM study of broken crept specimens revealed randomly distributed dislocations but no evidence of grain refinement, hence leading to the conclusion that dislocation glide was the dominant creep mechanism. The technological implication of the current study is that the welding process is safe for use as far as its creep properties are concerned. [ABSTRACT FROM AUTHOR]

This paper utilizes the plasma arc as the heat source to successfully fabricate well-formed thin-walled parts using combined cable wire duplex stainless steel 2209. Microstructure of parts exhibited the favorable two-phase ratio and the absence of σ-phase. It was found that appropriate heat input (1.68 kJ/cm) and cooling rate (5 °C/s) can effectively avoid the precipitation of σ-phase. Furthermore, the properties of the as-deposited samples were comparable to those of the samples heat-treated at 1300 °C, proving that no subsequent heat treatment was required for 2209 stainless steel fabricated by plasma arc additive manufacture. The samples showed excellent properties, in which the ultimate tensile strength and yield strength were improved by about 7% and 24% compared with GB/T4237-2015. The impact toughness meets the requirements of EN10028-7-2016, which is about 35% higher than that of the cold metal transfer samples, and the corrosion resistance is comparable to that of hot rolled 2205. [ABSTRACT FROM AUTHOR]

The creep behavior of an expansive clay under undrained conditions is investigated considering the effects of freeze-thaw-drying-wetting (FTDW) cycles. Compacted specimens were subjected to 1, 4, and 10 FTDW treatments. Macroscopic changes were recorded and mercury intrusion porosimetry tests were conducted to reveal the expansive clay's structure evolution during the FTDW treatments. The undrained shear strength was first determined by the consolidated undrained shear tests for as-compacted specimens. Subsequently, saturated undrained creep tests under low confining pressure were performed at various deviator stress levels (D) to study the axial strain development with time for specimens subjected to different FTDW cycles (NFTDW). Experimental results show that 1) the macropores increase with the newly emerged peak at a diameter between 10 µm to 20 µm and micropores decrease after FTDW cycles; 2) the axial instantaneous strain (εai), creep strain (εac), and total strain (εat) increase with FTDW cycles. The εai-D-NFTDW and εat-D-NFTDW relationships of the specimens are distributed on a unique surface under a certain confining pressure level; 3) the axial strain rate decreases dramatically within the first 2,000 min and then remains nearly constant. Studies in this paper are valuable for advancing the understanding of the influences of environmental factors on the creep behavior of expansive clays. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of nanomaterials' influence on improving the mechanical behaviour and microstructure of cemented soils. The strength characteristics were obtained through uniaxial compressive strength test. The influences of nanomaterials on the pore size distribution and micromorphology of cemented soil were investigated by nuclear magnetic resonance, scanning electron microscope, and X-ray diffraction. The results show that the uniaxial compressive strength of the cemented soil increases with the nano-SiO2 content. When the content is 4%, the strength of the cemented soil increases by about 40%. Improvement with nano-Fe3O4 shows different trends. The strength of the cemented soil increases with the nano-Fe3O4 content, reaching a peak at 3% of the nano content, and then decreases with the increase in the content. The transverse relaxation time spectrum curve of the cemented soil is trimodal, and the main peak covers a dominant area. Adding nanomaterials improves the pore distribution, transforms large pores into small pores, and greatly reduces the pores of the cemented soil. The porosity of the cemented soil decreases exponentially with the increase of nano-SiO2 content. On the contrary, with the increase of nano-Fe3O4 content, the porosity of the cemented soil specimen first decreases and then increases, the porosity reaches the minimum at 3% content. Nano-SiO2 and nano-Fe3O4 can effectively fill the internal pores of the cemented soil and accelerate the hydration process. In addition, nano-SiO2 participates in the hydration reaction of cement and has a good promoting effect on the mechanical properties of cemented soil. [ABSTRACT FROM AUTHOR]

Background: The potential effect of image noise artefacts on Digital Volume Correlation (DVC) analysis has not been thoroughly studied and, more particularly quantified, even though DVC is an emerging technique widely used in life and material science over the last decade. Objective: This paper presents the results of a sensitivity study to shed light on the effect of various noise artefacts on the full-field kinematic fields generated by DVC, both in zero and rigid body motion. Methods: Various noise artefacts were studied, including the Gaussian, Salt & Pepper, Speckle noise and embedded Ring Artefacts. A noise-free synthetic microstructure was generated using Discrete Element Modelling (DEM), representing an idealistic case, and acting as the reference dataset for the DVC analysis. Noise artefacts of various intensities (including selected extreme cases) were added to the reference image datasets using MATLAB (R2022) to form the outline of the parametric study. DVC analyses were subsequently conducted employing AVIZO (Thermo Fisher). A subset-based local approach was adopted. A three-dimensional version of the Structural Similarity Index Measure (SSIM) was used to define the similarity between the compared image datasets on each occasion. Sub-pixel rigid body motion was applied on the DEM-generated microstructure and subsequently "poisoned" with noise artefacts to evaluate mean bias and random error of the DVC analysis. Results: When the local approach is implemented, the sensitivity study on zero motion data revealed the insignificant effect of the Gaussian, Salt & Pepper, and Speckle noise on the DVC-computed kinematic field. Therefore, the presence of such noise artefacts can be neglected when DVC is executed. On the contrary, Ring Artefacts can pose a considerable challenge and therefore, DVC results need to be evaluated cautiously. A linear relationship between SSIM and the correlation index is observed for the same noise artefacts. Gaussian noise has a pronounced effect on the mean bias error for sub-pixel rigid body motion. Conclusions: Generating synthetic image datasets using DEM enabled the investigation of a variety of noise artefacts that potentially affect a DVC analysis. Given that, any microstructure – resembling the material studied – can be simulated and used for a DVC sensitivity analysis, supporting the user in appropriately evaluating the computed kinematic field. Even though the study is conducted for a two-phase material, the method elaborated in this paper also applies to heterogeneous multi-phase materials also. The conclusions drawn are valid within the environment of the AVIZO DVC extension module. Alternative DVC algorithms, utilising different approaches for the cross-correlation and the sub-pixel interpolation methods, need to be investigated. [ABSTRACT FROM AUTHOR]

This paper aims to present the determination of the creep behaviour of a globular microstructure aluminium 7075 alloy semi-solid metal feedstock billets under a constant temperature of 250 °C. Globular microstructures are often preferred in thixoforming processes due to their unique properties and favourable mechanical and high-temperature applications. Less attention has been given to globular microstructure even though the contribution of microstructure to creep behaviour is essential. Therefore, for this test, globular microstructure aluminium 7075 alloy feedstock billets were produced by the direct thermal method. The creep tests were conducted at different stress ranges from 30 to 70 MPa, and the effect of globular microstructure was examined. The results showed that the globular microstructure had the least deformation and the lowest creep rate at a longer deformation time. The fracture surface of the samples was then analysed with scanning electron microscopy (SEM). The microstructural changes that occurred during the test were investigated. SEM analysis revealed that the globular microstructure of the feedstock billet exhibits fewer voids and defects due to a uniform microstructure. The strain exponent value of globular microstructure billets was found to be at n = 4.6 in the stress range between 30 and 70 MPa at a constant temperature. This study is expected to provide an understanding of the creep behaviour of globular microstructures at high temperatures and high-stress conditions. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive metallurgical analysis conducted on representative samples obtained from two batches of 17-4PH steel rods in order to investigate the underlying factors contributing to the observed differences in their mechanical properties. The samples underwent a solution annealing process followed by an aging treatment to achieve H1025 temper condition. Surprisingly, the mechanical properties of one batch namely 91/5 were found to be inferior compared to the other batch 91/7, with only the latter meeting the specified requirements. To gain a deeper understanding of these differences, a range of analytical techniques were employed. Local variation in austenite stabilizers and its corresponding effect on microstructure of batch 91/5 was found to be the root cause of lower mechanical property. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of tests carried out on a titanium plate of a heat exchanger in which the flowing medium was hot gases with a temperature of 110 °C and a pH of less than 1. Strong hydrogenation of the titanium plate caused by the corrosion of the adjacent steel frame plate was detected. As a result of the synergy of the hydrogenation and erosion, a relative reduction in the thickness of the plate was observed locally by up to 94% in relation to the thickness of the titanium plate in the area not affected by degradation. The results of this study are not only of key engineering importance with regard to equipment design and the prevention of mechanical failures in titanium heat exchangers, but also with regard to equipment in other industries. [ABSTRACT FROM AUTHOR]

The phase changes of gypsum were considered to be sufficiently understood for a long time. However, due to the increasing importance of gypsum recalcination (connected with the planned closure of thermal power plants resulting in a lack of FGD gypsum) and new detailed research associated with it, gaps in the current knowledge have been discovered. This paper clarifies phenomena occurring during the production of gypsum binder, anhydrite, and potentially eco-friendly calcium sulfate-based ceramics at 22–1300 °C by in-situ XRD, thermal analysis, and SEM. It was found that undesirable insoluble anhydrite II arises even in the temperature range from 40 to 90 °C despite the current state-of-the-art. New knowledge about the existence of the individual phases, microstructure (cracking of crystals; fragmentation and sintering of anhydrite AII at temperatures above 700 °C when a ceramic-like material is formed), and their external consequences (changes in moisture and heat transport properties) has been gained. [ABSTRACT FROM AUTHOR]

Cow dung possesses potential agricultural and energy value but is often regarded as waste and underutilized in most cases. This wastage of resources not only poses a challenge to agricultural sustainability but also limits economic development in rural areas. Cow dung contains natural cellulose components like cellulose and lignin that are derived and used to prepare fiber materials. This paper explores a potential value-added application of agricultural waste, i.e., cow dung fibers to reinforce the alkali-activated slag composites (AASC), which are fabricated based on an industrial by-product slag. The raw and alkali treated cow dung fibers were characterized using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD). The porosity, density, water absorption, strength and drying shrinkage of AASC were tested and used to evaluate the effect of alkali treated fibers on the properties of AASC. The results showed that subjecting cow dung fibers to alkali treatment improved their surface roughness and thermal stability. The addition of cow dung fibers led to an augmentation in the splitting tensile strength of AASC, primarily due to the bridging action of these fibers. In particular, the 28-day splitting tensile strength of AASC containing 1 wt% of untreated cow dung fibers increased by 17.1% over the reference sample, and this increase was more pronounced in the alkali treated fiber sample. Moreover, the alkali treatment effectively reduced the effects of loss of compressive strength and increased drying shrinkage caused by fiber incorporation. The findings of this paper are helpful to solve the management problems of cow dung waste, reduce the environmental burden and realize the value utilization of resources. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of the microstructure, elemental and phase compositions of the eutectic alloy (wt %): Al–12.5 Si–0.8 Mg–0.4 Mn–0.7 Fe–0.9 Ni–1.8 Cu. A comparison of the microstructure of the alloy obtained at melt cooling rates of 102 and 105 K/s is made. It is shown that an increase in the melt cooling rate leads to the refinement of structural components, a decrease in the volume fraction of primary α-Al dendrites, an increase in the volume fraction of a mixture of eutectic silicon and aluminum, and a decrease in the silicon concentration in the interdendritic space from 23 to 13 wt %. Using energy-dispersive analysis and X-ray diffraction analysis, it was revealed that inclusions of intermetallic compounds Mg5Si6, Al17(FeMn)Si2, and Al3(CuNi)2 are formed at melt cooling rates of 102 and 105 K/s. A mechanism of the formation of a layered microstructure of an eutectic alloy is proposed. An explanation for the formation of X-ray amorphous nanosized particles in the foil layer adjacent to the mold is given. [ABSTRACT FROM AUTHOR]

Carbonated recycled powder as cementitious auxiliary material can reduce carbon emissions and realize high-quality recycling of recycled concrete. In this paper, microscopic property of recycled powder with three carbonation methods was tested through XRD and SEM, the mechanical property and microstructure of recycled powder mortar with three replacement rates were studied by ISO method and SEM, and the strengthening mechanism was analyzed. The results showed that the mechanical property of recycled powder mortar decreased with the increasing of replacement rate. It is suggested that the replacement rate of recycled powder should not exceed 20%. The strength index and activity index of carbonated recycled powder mortar were improved, in which the flexural strength was increased by 27.85% and compressive strength was increased by 20% at the maximum. Recycled powder can be quickly and completely carbonated, and the improvement effect of CH pre-soaking carbonation was the best. The activity index of carbonated recycled powder can meet the requirements of Grade II technical standard for recycled powder. Microscopic results revealed the activation mechanism of carbonated recycled powder such as surplus calcium source effect, alkaline polycondensation effect and carbonation enhancement effect. [ABSTRACT FROM AUTHOR]

Damage and fracture of archaeological potteries not only jeopardize the long-term preservation but also hinder their exhibition. To repair these pottery sherds effectively, this study introduces a novel inorganic phosphate-based adhesive and evaluates its effectiveness through a series of experiments. To determine the optimal base adhesive, the paper investigates the influence of varying weight ratios of the H2O–H3PO4 system and the Al(OH)3–H3PO4 system on properties including tensile lap-shear strength, microstructure, high-temperature resistance and phase composition. However, the original black color of the traditional CuO–phosphate adhesive limits its application. The innovation of this study lies in the addition of nano-TiO2 to the adhesive, which not only improves the bonding strength but also adjusts the color of the adhesive. This study has defined the optimal formulation (i.e., base adhesive = m[Al(OH)3]:m[H3PO4] = 7:100, filler = 10wt% nano-TiO2), and the final product shows no residual acid in adhesives. Additionally, the fracture surfaces are successfully bonded with a high strength of 3.56 MPa. Various ageing tests including dry-thermal ageing, hygrothermal ageing and UV irradiation ageing are conducted to assess the ageing resistance of the inorganic phosphate-based adhesive. The results indicate strong tolerance of adhesive to high temperature and high humidity environment. Preliminary applications in archaeological pottery restoration suggest that the inorganic phosphate-based adhesive offers considerable promise for repairing shattered pottery. [ABSTRACT FROM AUTHOR]

Skew rolling is a manufacturing process in which two or three rolls are used to reduce the diameter or modify the shape of a cylindrical workpiece, which is used to manufacture mechanical components such as shafts, rods or balls. Hot conditions are used to overcome limitations related to material ductility, residual stress and machine capacity. In this paper, the warm skew rolling (WSR) process of 42CrMo4 rods is modeled by the finite element method. The effects of forming parameters, namely initial temperature and roll rotational velocity, on the material strain rate, thermal properties, microstructure and hardness were analyzed. Simulation results were validated by experimental process data, while hardness tests and SEM-EBSD microscopy were used to assess mechanical properties and microstructure, respectively. The WSR resulting microstructure is different from the normalized ferritic–pearlitic initial one. The degree of spheroidization (DoS) of cementite increases with temperature. The maximum DoS of 86.5% occurs at the initial temperature of 750 °C, leading to the highest material softening. Rolling from lower temperatures favors grain fragmentation and the achievement of incomplete spheroidization, which, in combination with the highest proportion of high-angle boundaries, contributes to a higher hardness of the rods with respect to those rolled at higher temperatures. The highest reduction in hardness takes place at 750 °C and 30 rpm, leading to 209.4 HV1 (30.7% reduction) and 194.1 HV1 (35.7% reduction) in the near-surface and internal regions, respectively. The driving factor is the transformation of cementite precipitates into a spheroidal form characterized by the greatest degree of dispersion. [ABSTRACT FROM AUTHOR]

Conventional welding heat sources (electron beam, plasma, arc, and laser) are widely used in metal additive manufacturing (AM), where melted and fused materials are drawn into desired shape, size and structure. Despite welding and additive manufacturing using similar procedures, AM has been primarily done using new computer numeric control CNC technologies, permitting the manufacturing of the higher-resolution component than ever before. On the other hand, numerous working tactics utilized in AM variations are quite similar to welding. Juxtaposing the two will show how the knowledge obtained in technology and welding science over the previous decades can be used for the rapidly emerging field of metal additive manufacturing. This paper depicts the review of the differences and similarities of both the processes in accordance to the processes, surface finishes, deposition rate, microstructure, macrostructure and mechanical properties. [ABSTRACT FROM AUTHOR]

This paper investigates the thermo-mechanical and wear characterization of AA8011 aluminum alloy matrix based hybrid metal matrix composite reinforced with graphene and boron carbide (B4C) particles as reinforcement material. The weight percentage (wt.%) of graphene was maintained as 1 and wt.% of B4C was varied from 3 to 9 wt.% in steps of 3 wt.%. The influence of reinforcements and their wt.% on tensile, hardness, density, thermal and wear characteristics of AA8011 aluminum alloy matrix based hybrid metal matrix composite reinforced with graphene and boron carbide (B4C) particles were detailed. The morphology and microstructure of the composite specimens were interrogated through scanning electron microscope, transmission electron microscope and optical microscope. The X-ray diffraction spectrum ensured the presence of graphene and B4C reinforcements and the AA8011 aluminum alloy matrix in the fabricated composite specimens. The graphene and B4C reinforcements in AA8011 aluminum alloy matrix improved the tensile, hardness and wear characteristics of composite specimens by 19.8, 36.1 and 50.9% respectively for the composite specimens with 1 wt.% graphene and 6 wt.% B4C reinforcements. The optimal wt.% of reinforcements maximize the grain boundaries resulting in better mechanical and wear characteristics. [ABSTRACT FROM AUTHOR]

The paper is dedicated to investigating the comparative tribological characteristics of the AlSi10Mg aluminum alloy obtained by the selective laser melting with and without NiP coating on the surface. Studies were conducted under various friction conditions. Research was conducted to assess the possibility of applying the NiP coatings on the surfaces of thin internal channels of parts for aircraft engines and power plants. [ABSTRACT FROM AUTHOR]

The concept set-on-demand in the context of digital fabrication refers to a long enough open time of fresh concrete during the delivering process but a quick strength build-up after extrusion, which is indispensable to achieve a high construction rate. In this paper, we explore the hydration and microstructure of a combination of two reactive streams including a retarded calcium sulfoaluminate (CSA) mixture and a Portland cement (PC) mixture. Experiments were conducted on both the constituent mixtures and the combined mixtures with different volume ratios of the constituent mixtures. Hydration heat release, hydration products, pore structure, early-age mechanical behavior, and autogenous shrinkage are specifically investigated. It is concluded that the PC mixture can be effectively used to trigger the initial hydration of the retarded CSA cement, whereby the formation of ettringite can be boosted depending on the volume ratio of the CSA mixture to the PC mixture. In addition, it is shown that the difference in the volume ratio affects the pore structure and the autogenous shrinkage behavior, which can be well correlated to the phase assemblage of the CSA-PC system. [ABSTRACT FROM AUTHOR]

This paper reports on microstructure evolution, phase formation, microhardness, compressive stress–strain relationship, fractography, and sliding wear characteristics of multi-layer depositions of equiatomic Ti–Nb–Zr–Mo–Ta high entropy alloy (TNZMT HEA) by µ-plasma metal additive manufacturing (µ-PMAM) process. Microstructure evolution revealed that multi-layer deposition of TNZMT HEA comprises of major body centred cubic (BCC) phase having fine-dendritic structure and minor BCC phase having inter-dendritic structure. These phases are formed due to minor elemental segregation, higher cooling rates, and decomposition of single BCC phase. Microhardness of µ-PMAM deposited TNZMT HEA is 520 ± 10 HV which is much higher than the vacuum arc-melted TNZMT HEA. It is due to absence of dislocations and grain boundaries. Its Young's modulus, ultimate compressive strength, compressive yield strength, and compressive strain are found as 130 ± 4 GPa; 1892 ± 15.6 MPa; 1847 ± 25.8 MPa; and 13.53 ± 1.59% respectively. Minor decrease in stress is observed after yielding which may be due to dislocation unlocking by solute atoms or the ending of short-range order by dislocation motion. Its average coefficient of sliding friction, average worn-scar depth, and formation of macro-groove and delamination increases but specific wear rate decreases with the increase in applied load. Smaller values of applied load resulted in lesser wear debris which is confirmed by EDS analysis of the worn-surfaces. This study confirms that µ-PMAM deposited TNZMT HEA is a better knee implant material due to its better microstructure, smaller value of Young's modulus, larger compressive yield strength, higher microhardness, and improved sliding wear resistance. [ABSTRACT FROM AUTHOR]

As a new concrete crack patching technology, microbial self-healing slurries offer favourable characteristics including non-pollution, ecological sustainability and good compatibility with concrete. In this paper, a nano-sio2-modified microbial bacteria liquid, combined with sodium alginate and polyvinyl alcohol, was used to prepare a nano-modified microbial self-healing slurry. This slurry was used to coat concrete under negative pressure in order to verify its restoration effect, and the micromorphology of the resulting microbial mineralization products was observed. The results revealed that patching the concrete using the nano-modified microbial slurry significantly improved its permeability, and increased its carbonization resistance by three times in comparison with the control group. Through a combination of Scanning electron microscopy (SEM) and X-ray diffraction (XRD) observation, it was determined that the microbial mineralization reaction products were mainly calcite crystals, which, integrated with the nano-sio2, sodium alginate and polyvinyl alcohol at the microscopic level, filled the internal pores of concrete, thus improving its durability. Highlights: • Surface crack treatment of concrete using a nano-modified microbial slurry was investigated. • Patching concrete using nano-microbial slurry clearly improved its chloride penetration. • The carbonization of the concrete was three times in comparision with the control group. • The main product of the microbial mineralization reaction was calcite crystal. [ABSTRACT FROM AUTHOR]

In this paper, a new severe plastic deformation process, namely direct extrusion and variable channel shear deformation (DEVCS), is proposed as a new composite extrusion preparation process for magnesium alloy tubes, which is composed of direct extrusion and unequal channel extrusion. The magnesium alloy tubes with excellent properties can be prepared by DEVCS process. However, the recrystallization behavior and the structure evolution during extrusion are still unclear. In this paper, the forming process of DEVCS was analyzed by DEFORM-3D™ finite element software combined with the metallographic microscope and the electron backscatter diffraction. The results show that the shear deformation in the DEVCS process is conducive to the improvement of strain and strain rate. The high dislocation density in the shear deformation zone promotes the dynamic recrystallization, and the grain size of AZ31 magnesium alloy is improved. In addition, IGMA analysis confirmed that non-basal slip systems were strongly activated during DEVCS process. [ABSTRACT FROM AUTHOR]

Image-based micromechanical models, necessary for the development of structure-property-response relations, are far from mature for complex microstructures with multi-modal distributions of morphological and crystallographic features, such as those occurring with cold spray-formed (CSF) aluminum alloys. These materials have a bimodal polycrystalline microstructure composed of recrystallized ultra-fine grains (UFGs) and deformed coarse grains (CGs) within prior particles. A prime reason is the lack of robust approaches for generating statistically equivalent virtual microstructures (SEVM) capturing the statistics of characteristic morphological and crystallographic features, such as grain size, crystallographic orientations, and misorientations. This paper introduces an approach, strategically integrating Generative Adversarial Network-based approaches for producing bimodal CSF AA7050 alloy microstructures, with the synthetic microstructure builder Dream3D for packing prior particles with CGs having statistically equivalent morphological and crystallographic descriptors to electron backscatter diffraction (EBSD) maps. An efficient finite element (FE) simulation approach is developed for the SEVMs to generate local and overall response functions through the creation of sub-volume elements (SVEs). [ABSTRACT FROM AUTHOR]

In biomedical Ti–Mg composites, Ti skeleton is conducive to the growth of new bone tissue, and the connected pore structure generated by the degradation of Mg can promote the transport and exchange of human body fluids. The combination of Ti and Mg can effectively reduce the elastic modulus of the composite and make it more suitable for human tissue. This paper attempts to prepare biomedical Ti–xMg (x = 8, 12, 16 and 20) composites by microwave sintering. In order to determine the optimal ratio of biomedical Ti–Mg composites, metallographic microscope, scanning electron microscope, X-ray diffractometer, electronic universal pressure testing machine and electrochemical workstation were used to study the effects of Mg content on the microstructure, mechanical properties and corrosion resistance of the composites. The results show that with the increase of Mg content, the pore defects of the composites decrease, the porosity decreases, the density increases, the compressive strength and elastic modulus decrease, and the corrosion resistance decreases. The compressive strength of Ti–16Mg is 385 MPa, the elastic modulus is 27.87 GPa, the self-corrosion potential is –1.14 V, the corrosion current density is 1.32 × 10–3A cm–2, and the polarization resistance is 295.83 Ohm cm2. Overall results highlighted the potential of biomedical Ti–16Mg composites for various possible orthopedic applications. And The combination of low elastic modulus, high compressive strength, improved corrosion resistance, and enhanced bioactivity makes biomedical Ti–16Mg composites fabricated by microwave sintering process potential and promising candidates for orthopedic applications. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure and mechanical properties of AlSi10Mg and 5052/AlSi10Mg connectors involved in the welding package of electronic control system components of new energy vehicle chargers were studied. The results show that the grains in stir zone of the two joints are obviously refined due to dynamic recrystallization by electron backscatter diffraction technique. The grains in stir zone of AlSi10Mg are broken into particles by the precipitate phases pinning effect, showing a finer state. The grain size and precipitate phases distribution in different regions lead to different hardness in different regions of the joint. The tensile strength of the AlSi10Mg joint is 229 MPa, which is 95.4% of AlSi10Mg. The minimum hardness and the fracture position are both in the heat affected zone at the top of the joint advancing side. The tensile strength of 5052/AlSi10Mg joint is 179 MPa, reaches 90% of 5052-H32 and 74.5% of AlSi10Mg, respectively. The fracture position is at the junction of the two aluminum alloys, and the minimum hardness is located in the heat affected zone of 5052-H32. [ABSTRACT FROM AUTHOR]

As the aerospace industry continues to grow, so does the demand for new materials that can withstand high temperatures and corrosive environments. In this paper, materials from the Ti–Al–C system that thrives in the aforementioned environments are studied. The method of measuring the grain size was described according to the relevant standards. The geometrical parameters of titanium carbide and its volume fraction have been determined under the ASTM E112 and ASTM E562 standards, respectively, for two series of specimens that were produced with different parameters and methods. The grain sizes determined are G12 and G12.5 according to ASTM E112. The volume fractions determined for the two series of samples are 20.22 and 17.65%, respectively. Using the above parameters, elastic and shear modulus, and Poisson's ratio were determined for the specimens tested using RVE modeling. RVE results showed that materials with higher volume fractions and larger average grain size resulted in stiffer materials. Specimens with higher TiC content exhibited higher elastic and shear modules, which were 153.6 and 58.3 GPa, respectively. Poisson's ratio was the lowest at 0.315. However, the difference was not significant between the specimens, the elasticity and shear modulus, of a specimen with a lower concentration of TiC, are 145 and 55.2 GPa, respectively. Poisson's ratio was higher and equal to 0.319. Comparing the above properties with the popular aerospace alloy Ti–6Al–4V, both specimens are much stiffer. [ABSTRACT FROM AUTHOR]

In the past research, there was a gap in the field of Al/Cu dissimilar metal welding with Ag intermediate layer, and attention to the joint resistivity is insufficient. This paper has used laser welding to study this problem. The mechanical and electrical properties of the joints were tested, and the microstructure and fracture surface of the weld were observed, along with the analysis of their phase composition and formation mechanism. The results show that the Ag–Al–Cu ternary system forms on the weld, and Ag inhibits the formation of IMC in the Al/Cu system, with the main IMCs being Al2Cu and Ag3Al. Part of the Ag-rich and Al-rich phases are dispersed in small particle shape, providing a strengthening effect in various areas. After adjusting the welding parameters, excellent joints can be obtained, with a tensile strength of 98.05 MPa, which is 78.5% of the base metal, and a resistivity of 2.47 μΩ cm. The fracture occurs in the softened zone of the Al-side base metal, indicating a ductile fracture. These findings have demonstrated that good mechanical and electrical properties can be obtained by adding Ag as an intermediate layer of the joint. [ABSTRACT FROM AUTHOR]

In the realm of additive manufacturing, powder bed fusion (PBF) is recognized as an innovative and highly effective technique for manufacturing titanium-based materials. With an understanding of and regulation for the complex microstructural evolution that occurs during the PBF process, several previous studies have been conducted to enhance the reliability, efficiency, and performance of the PBF through investigation and optimization of microstructure evolution in PBF. These studies have examined various aspects, including feedstock materials, process parameters, and post-processing techniques, in order to gain a comprehensive understanding and control over the progression of microstructure in the PBF. Process parameters are widely acknowledged as critical determinants in the PBF process for titanium-based materials, significantly influencing the quality in 3D printed components. Previous studies have provided an in-depth discussion of the effects of process parameters, such as laser power, scanning speed, and hatching space, on the microstructure evolution of Ti-based materials. The primary objective of this review paper is, therefore, to provide a comprehensive and clear explanation of recent efforts, with a particular focus on investigating the complex evolution of microstructures in Ti-based materials during the PBF process. This thorough discussion is devoted to providing a comprehensive understanding of the effects of process parameters on the evolution of microstructures in Ti-based materials. [ABSTRACT FROM AUTHOR]

The focus of this paper was on welding AISI H13 tool steel by the cold metal transfer method to investigate the effects of welding variables on weld bead geometry, microstructure, and mechanical performance. The variable sets consisted of welding voltages of 16–24 V and speeds of 0.25–1.25 mm/s. The weldments were smooth without weld seam defects due to low-voltage welding. The weld bead height was variably influenced by the welding process factors as the welding voltage increased and the welding speed remained constant. The bead height decreased with increasing voltage. Conversely, the dilution percentage increased as the voltage increased. While maintaining a low voltage, a higher bead width was formed. The optimized conditions were achieved at 18 V and 0.25 mm/s, with a bead height of 8.8 ± 0.1 mm, bead width of 17.5 ± 1.0 mm, and penetration depth of 3.59 ± 1.1 mm. However, the influences of the welding speed on microstructural changes were less significant than those of the welding voltage. The voltage had a minimal influence on the ferrite phase formation of the weld metal and heat-affected zones. The mechanical properties, such as the impact toughness of the welded seam, imparted the material with higher absorbed impact energy than the parent material. The impact toughness decreased with an increase in welding voltage. Moreover, the fusion zones of the weldments had lower hardness values than the heat-affected zones and base material. The chromium contents in the microstructure significantly affected the microstructure and microhardness characteristics of the weld metal and heat-affected zones. [ABSTRACT FROM AUTHOR]

In recent years, Sn-Bi solder has been widely used in the electronic packaging industry due to its low melting point. However, the segregation and coarsening of Bi will degrade the mechanical properties of solder joints. In this paper, the shear strength of Sn-Bi/(111)Cu joints is enhanced by refining the distribution of Bi in the composite solder. Bi diffuses in the Sn-Sn58Bi layered composite structure in the reflow process, resulting in inhibition of coarsening. In addition, the growth behavior and orientation of Cu6Sn5 in Sn58Bi/(111)Cu and Sn-Sn58Bi/(111)Cu solder joints are also investigated. [ABSTRACT FROM AUTHOR]

Lightweight bent aluminum profiles are widely utilized in transportation fields. In this paper, the torsional channel self-bending extrusion process (TCSE) was adopted to machine AA6063 bent aluminum profiles in a single operation to verify the process's feasibility. Effects of extrusion parameters on the curvature, microstructure, and mechanical properties of the profiles were researched, and the extrusion process was simulated. The results show that the extruded profiles had good curvature stability. The grains were equiaxed in the cross longitudinal section, and the grain size at the outside diameter (OD) position was smaller than the inside diameter (ID) position. When the difference in deformation temperature at the OD edge was above 31 K, a smaller peripheral coarse grain (PCG) layer was formed at the OD edge with a thickness of about 400 μm, resulting in reduced hardness. The Mg2Si particles served as the main strengthening phase, which increased in number and decreased in size with increasing billet temperature and extrusion speed. Increasing the billet temperature and speed improved the mechanical properties of the material, with an increase in average hardness of 55.9% and 19.5%, and ultimate tensile strength (UTS) of 12.5% and 7.1%, respectively. By comprehensively considering the factors of extrusion load, microstructure, and mechanical properties, the optimum bent profile for different curvatures was determined. When a large curvature (≥328.67 mm) was required, it was preferred to increase the billet temperature. When a smaller curvature (≤328.67 mm) was required, it was advisable to increase extrusion speed. [ABSTRACT FROM AUTHOR]

This paper considers the applicability of high-velocity forming by investigating the compound explosion process of electrical and chemical energy in electric-pulse-triggered energetic materials loading (ETEL). The deformation behavior of DP600 steel sheets during ETEL and wire explosion loading (WEL) is studied by experiments, numerical simulation, and microstructure analysis. The increment of quantized energetic materials (EMs) (0.5 g) on the deformation volume of the sheet is reduced during ETEL, indicating that triggering more EMs at the same discharge energy reduces its energy utilization. The percentage contribution of different discharge energies triggering the same mass of EMs to the deformation volume of the sheet has no effect, with 1.0 g EMs contributing about 35.5%. Compared with WEL specimens of a similar bulging height, an appropriate increase in discharge energy in ETEL is beneficial to improve the energy utilization. The relationships between the kinetic energy, plastic strain energy, stress, and strain of the sheets during ETEL/1.5 g and WEL/5472 J are analyzed by numerical simulation. The results show that ETEL has a smaller stress gradient difference than WEL, indicating that ETEL changes the stress distribution in the deformation zone and expands the strain distribution range. Compared with WEL/5472 J, the low angle grain boundary (LAGB) fraction of ETEL/1.5 g increases, and dislocations are uniformly distributed in the grains and disperse the strain concentration at the grain boundaries. The fracture specimens of ETEL also show multiple necking bands, large and deep dimples, and thicker tear ridges, indicating a significantly higher degree of deformation. [ABSTRACT FROM AUTHOR]

TiAl-based alloys represent a novel class of lightweight, high-temperature structural materials that exhibit exceptional properties, including low densities, high specific strength, and remarkable thermal resistance. These properties make them exceedingly promising for supplanting nickel-based superalloy in the production of pivotal components for aerospace, marine, and automotive engines. Regrettably, like most intermetallic compounds, TiAl-based alloys are subject to certain shortcomings, such as room-temperature brittleness, deformation difficulties, and susceptibility to cracking, which present challenges for shaping these materials into intricate forms using traditional processing methods. In this regard, additive manufacturing (AM), with its high processing freedom and energy, has emerged as a revolutionary technology for the fabrication of complex structural components of TiAl-based alloys. However, AM TiAl-based alloys are still plagued by issues such as cracking, porosity, and uneven microstructure. Therefore, various post-processing techniques were employed to tune the microstructure, and thus enhance the performance of AM TiAl-based alloys. This paper reviews the research progress of AM TiAl-based alloys, summarizing the effects of process parameters, alloying, heat treatment, and surface treatment on the microstructure and mechanical properties of these alloys. Additionally, it discusses the challenges and prospects for the future development of AM TiAl-based alloys. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive investigation on anti-seepage/erosion performance of a hydroxypropyl starch (HPS)-based coupling agent (CA) amended clay/sand as the cut-off wall materials under vacuum suction. The experiments, including the permeability, erosion, water-bleeding, viscosity, and microstructure by scanning electron microscopy (SEM) and mercury intrusion porosity (MIP) were conducted. It reveals that the very low CA incorporation can effectively reduce the clay mineral's migration and bleeding volume of the soil slurry, and results in a lower hydraulic conductivity from 4.2 × 10–5 cm/s to as low as 1.0 × 10–6 cm/s, and a 45.4% decrease in erosion mass with just 0.2% CA addition. Microstructural analysis indicates that CA addition enhances hydrogel bonding, increases viscosity, and reduces bleeding volume, effectively mitigating clay erosion under vacuum suction. The findings not only are beneficial for the introduction of the hydroxypropyl starch (HPS)-based coupling agent into the sand/clay mixture's modification, but also provide insights into the CA incorporation mechanism for improving the anti-seepage performance of clay/sand cut-off wall in vacuum preloading projects. [ABSTRACT FROM AUTHOR]

The fuel tank of the heavy launch vehicle is made of high-strength aluminum alloy 2219 with a thickness of 18 mm. The assembly process is mainly based on friction stir welding (FSW) technology. The increase in tank thickness intensifies the non-uniformity of temperature distribution and then affects the microstructure and mechanical properties of different areas of the joint. At present, the research on the influence of process parameters on temperature field, microstructure, and mechanical properties of FSW thick aluminum alloy 2219 plate is still blank. In this paper, temperature measurement experiments of FSW 18-mm-thick aluminum alloy 2219 are conducted by using thermocouple temperature measurement method. Then, combined with the microstructure observation and tensile test of welded joints, the thermal cycle temperature, microstructure, and mechanical properties of the joints under different rotation speeds (n), welding speeds (v) and pitch ratio (n/v) are explored. The research provides reference for selection of welding process parameters to ensure high quality of FSW thick aluminum alloy 2219 plate. [ABSTRACT FROM AUTHOR]

This paper presents new technology for stainless steel wire processing. This technology consists of using cryogenic cooling immediately after the wire leaves the drawing die. Results of a laboratory experiment show that use of cryogenic processing after wire drawing improves mechanical properties compared with traditional drawing. Metallographic analysis proves that deformation conditions during cryogenic drawing are an additional factor for realization of structural resources to optimize steel wire physical and mechanical properties. [ABSTRACT FROM AUTHOR]

The selection of MgFeSi alloy and inoculants used for ductile iron treatment has confounded members of the foundry industry for many years. Frequently foundries have used certain types of alloys "because they have always done it that way" or "because someone else was doing it." The current study involves ductile iron produced with three grades of MgFeSi with varying levels and types of rare earths along with four different inoculants. The iron was cast into test samples of various thickness from 2×2×8 inches to 10×10×8 inches. Mechanical properties and microstructures were evaluated at multiple locations in each of the 36 samples for a total of 156 points of data. In this paper, we will summarize the findings for differing section sizes. [ABSTRACT FROM AUTHOR]

SiC-TiB2 composite ceramics of the solid-state has stable property in high temperature with wide application. In the paper, SiC-TiB2 composite ceramics was prepared by spark plasma sintering with 50 MPa pressure and heat preservation for 10 min at 1750 ℃, and the effect of TiB2 content (0 vo l%-20 vol%) on microstructure and mechanical properties of SiC composite ceramics by solid-state spark plasma sintering was investigated. The experimental results show that the grain growth of SiC is inhibited with the increase of TiB2 content. When TiB2 content is 20 vol%, TiB2 promotes the decomposition of SiC into Si, which is located in the grain boundaries of SiC and TiB2 to reduce mechanical properties of composite ceramics. SiC-15 vo l%TiB2 composite ceramics have the preferable comprehensive mechanical properties with relative density, Vickers hardness, bending strength and fracture toughness of 98.8%, 27.2 GPa, 431 MPa and 5.24 MPa • m1/2, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the effect of ultrasound on the microhardness and microstructure of friction stir welding joints is investigated. It has been found that the area with minimum microhardness is located in the thermomechanically affected zone on the retreating side. An ultrasonic impact resulted in an increase in the size of this area. The weakening of the region is attributed primarily to the low content of hardening particles due to overaging. It was also found that the ultrasonic impact during welding resulted in a 5 times reduction of residual stresses. [ABSTRACT FROM AUTHOR]

The dispersion and reflection characteristics of coupled waves in the piezomagnetic solid with flexomagnetic microstructure effect are studied in this paper. The flexomagnetic effect, strain gradient effect and micro-inertia effect are introduced into the constitutive equation and the governing equation to establish the wave propagation theory in the piezomagnetic solid with flexomagnetic microstructure effect. The secular equation of wave propagation is derived, and the properties of five coupled waves are analyzed. The dispersion characteristics of coupled waves and the reflection properties of coupled waves at the free boundary are solved numerically and checked by the energy conservation law. The influences of the flexomagnetic effect, strain gradient effect and micro-inertia effect on the wave propagation are discussed. It is found that the flexomagnetic effect mainly enhances the mechanical-magnetic coupled property, strain gradient effect mainly enhances the elastic property, and micro-inertia effect not only enhances the inertia property, but also essentially changes the dispersion characteristics of coupled waves. [ABSTRACT FROM AUTHOR]

This paper presents a thorough manufacturability study of 2507 super duplex stainless steel (SDSS) produced by the Laser Powder-Directed Energy Deposition (LP-DED) process. First, experimental observations on single-track surface morphology and geometrical characteristics are described. Then, dimensional and porosity analyses of thin walls and bulk samples are presented and discussed in order to identify the optimal process parameter combinations, from a process point of view, for further characterizations to determine the general properties of LP-DED-printed samples. Finally, the results obtained on wrought steel of the same grade are compared to those of the printed material in terms of microstructure, texture, and ferrite/austenite ratio. A set of meticulously chosen process parameters with regard to the process and the machine (nozzle size, maximum power deliverable) gives the optimal results for the as-built LP-DED material in terms of porosity and microstructure quality but with smaller grains (irrespective of the phase studied) and a higher proportion of ferrite (about 75%). [ABSTRACT FROM AUTHOR]

With development of present energy-saving society, lightweight and green development in the automotive and aerospace industries have put forward urgent demands for heat-resistant cast aluminum alloys. Present cast aluminum alloys are of lightweight and have excellent mechanical properties when serving in ambient environment. However, when serving at temperatures of 200–300 ℃ or even higher, the alloys inevitably soften and the high-temperature mechanical properties decline rapidly, hardly meeting the requirements for high-performance equipments. This paper summarizes the development process of classic heat-resistant aluminum alloys, especially the microstructural characteristics of heat-resistant cast aluminum alloys in the past decade, and reviews the current microstructure tuning strategies of heat-resistant aluminum alloys from the aspects of intrinsic heat resistance of the second phases, phase interface modification, diffusion-controlled phase transition, grain boundary stabilization and composite material design. Finally, we propose the prospects for the future development of heat-resistant aluminum alloys. [ABSTRACT FROM AUTHOR]