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Traditionally, cellulose nanofiber (CNF) production has primarily relied on virgin cellulose sources. Yet, the shift to using paper mill sludge (PMS) as a source for CNF underscores the significance of reusing and recycling industrial byproducts. PMS contains significant amounts of cellulose that can be extracted as a raw material. The purpose of present study is to provide a sustainable approach to PMS utilization as a paper coating additive in the cellulose nanofibrils (CNFPMS) form via simply scalable wire-wound rod coating method. The effect of CNFPMS additive amounts at two coating layers on microstructure and surface properties of coatings such as porosity, air permeability surface roughness and optical properties such as brightness, gloss and CIE L*a*b* is studied, which they can also provide insight for the eventual print performance. Results indicated that the obtained CNFPMS in paper coating shows 52% decrease in porosity, presenting significant improvement in the coating microstructure. The marginal increase in permeability coefficient and surface roughness, 54% and 10%, respectively, suggests improving color reproduction and preventing color density losses. Optical analysis showed slight decrease in brightness and gloss, as was expected. Notably, the lightness was improved, which also indicates increasing color gamut volume in printing applications. As a result, the current work offers a sustainable approach to manage PMS for use in paper coatings as a high-value-added material. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is chosen as a coating material on industrial Kraft paper substrates to impart a barrier against air, grease, and water. This is an excellent initiative to replace the existing non-biodegradable and petroleum-based coating materials used in many industrial products such as packaging and coated abrasives. In this study, the effect of the crystallinity of PLA on its barrier properties is evaluated. Initially, amorphous and semi-crystalline PLA (sc-PLA) are compared for properties such as coating weight, gloss, heat seal strength, air resistance, grease resistance, contact angle, water resistance, and water vapor transmission rate (WVTR). Sc-PLA is observed to show better barrier properties than its amorphous counterpart. To understand if the barrier properties imparted by a biodegradable coating material on Kraft paper will improve with an increase in crystallinity, sc-PLA is compared to a more crystalline biodegradable polymer, polycaprolactone (PCL). The results indicate that PCL shows compromised results with respect to sc-PLA as a barrier coating material. The theory behind this effect is discussed, and the two bio-based polymers, namely, PLA and PCL, are also comparatively evaluated against the conventionally used synthetic barrier coating materials, acrylic, and varnish, on identical paper substrates under identical process conditions. SEM and DSC analyses on amorphous PLA, sc-PLA, and PCL coatings are also conducted to decipher the microstructural traits of these macromolecules. Sc-PLA serves as an ideal barrier coating material on Kraft paper, and it possesses better hydrophobic properties than untreated, PCL-treated, acrylic-treated, or varnish-treated Kraft paper substrates. [ABSTRACT FROM AUTHOR]

The paper proposes a new approach to gradient porous composites based on the Ti3Al(Si)C2 MAX phase. This approach is based on the production of preceramic paper with the different content of the powder filler based on MAX phases and their spark plasma sintering. The analysis of the microstructure and phase composition is conducted for these composites. It is shown that the obtained composites have a clear interface between layers with different porosity. It is found that the content of organic components in preceramic paper affects the phase composition of the fabricated composites. The MAX phase content in dense and porous layers is 86 and 56 vol.%, respectively. Microhardness measurements performed in the composite cross-section show the hardness of 600 to 800 HV, depending on the layer porosity and phase composition. [ABSTRACT FROM AUTHOR]

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]

The history of antimony modification of Al–Si casting alloys is reviewed, together with the important technical and commercial reasons why antimony is no longer used as a modifier. [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]

The paper is devoted to the formation of SiC-ceramics from preceramic paper. Preceramic paper is a comparatively novel material consisting of a cellulose matrix and a powder filler. It is flexible and amenable to mechanical processing. This makes it possible to form multi-layer paper composites for sintering, where the composition, shape, and properties of each individual layer can be controlled. SiC-ceramic samples have been obtained by spark plasma sintering of preceramic paper based on a SiC powder (90 wt %) as a feedstock. The surface microphotographs of the obtained SiC-ceramics were analyzed. The values of density, porosity, and water absorption were determined. The phase composition and pore size distribution over the material structure were established. Based on the results, the effect of spark plasma sintering parameters (holding temperature and pressing pressure) in the ranges of 5–100 MPa and 2100–2200°C, respectively, on the structure-phase state formation of the SiC-ceramics was investigated. [ABSTRACT FROM AUTHOR]

The paper studies the chemical and phase composition of the product from heat-resistant nickel-based superalloy formed by wire-feed electron beam additive manufacturing (EBAM). Microsegregation on macro-(dendrites/interdendritic space) and microscale (γ/γˈ) was evaluated. It is shown that in additively formed material, there is a significant (by an order of magnitude) refinement of structural and phase elements. The degree of microsegregation remains unchanged after the additive process, despite the increase in the volume fraction of dendrites, and the complex thermal history does not lead to the formation of undesirable phases. [ABSTRACT FROM AUTHOR]

Transparent, flexible, and high-performance triboelectric nanogenerator (TENG) from nature-derived materials are required for sustainable society development. However, low triboelectricity from natural material is generally observed. Tunable electronic band diagram (EBD) through facile manipulation is one of the efficient methods to promote the TENG output, requiring fundamental, in depth understanding. Herein, we employed the high quality, single crystal-like Ti2NbO7 nanosheets (NSs) with dual dielectric and semiconducting properties as filler for bacterial cellulose (BC)-based TENG. Several techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet—visible (UV—vis) absorption, energy dispersive X-ray spectroscopy (EDS), and synchrotron radiation X-ray tomographic microscopy (SRXTM) were applied to characterize the long-range structure, microstructure, optical properties, elemental composition, and three-dimensional (3D) distribution of components in the composites. The semi-transparent and flexible 5 vol.% Ti2NbO7 NSs/BC preserved the integrity of cellulose, contained well-dispersed nanosheets, reduced optical band gap (4.20 vs. 5.75 eV for BC), and increased surface roughness. The dielectric permittivity and conductivity increased with nanosheets content. Adding negatively-charged Ti2NbO7 NSs could regulate the charge affinity of BC composite via shifting of Fermi energy over that of Al. It is found that adding 5 vol.% NSs into the BC film improved electrical outputs (~ 36 V and ~ 8.8 µA), which are 2–4 times higher than that of pure BC, even when paired with Al which lies adjacent in triboelectric series. Our work demonstrated the method to enhance BC-based TENG performance through EBD regulation using multifunctional Ti2NbO7 NSs. [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]

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]

A method for controlling the parameters of a fibrous cellulose-containing material using the 3D microstructure is described. The developed method for studying the interaction of the fibers using 3D simulation can be used for prediction and quality control of paper and cardboard. The determined parameters include the volume and porosity, dimensions of the fibrous cellulose material, fiber volume, and uniformity of their distribution. The described method can also be used to predict to a certain degree the physicomechanical parameters from the 3D microstructure of samples of fibrous cellulose material, namely, from the estimated contact surface between the fibers and the dimensions of their distribution. The 3D model of the fibers was developed using a graphics program working with files. Microscopic sections of the fibrous composite material that were then digitized and separated by 5 μm were presented. Then, the Loft command of the graphics editor was used to extrude a plane and form a 3D body of fibrous composite that could produce a 3D model of the fibrous microstructure. An algorithm of actions to determine and predict the properties of the fibrous composite material by analyzing its 3D microstructure was derived. [ABSTRACT FROM AUTHOR]

The results of graphical and analytical processing of microstructures of multilayer fibrous composite materials are described. The results obtained with use of two software packages that make it possible to process the cross-section microstructure of a fibrous material are compared. The areas of fiber cuts are determined, from which the porosity of the cardboard is estimated. These data are compared with the results of graphical and analytical processing with use of the ImageJ software package. [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]

Since, in modern high-performance sports, the technical component is decisive, the ski running surface is an important element of cross-country skiing. This paper presents a review of papers on sliding mechanics, discusses modern methods for improving it, and considers the prospects for the development of this area under current energy and environmental conditions. Various factors affecting the sliding mechanics, in particular, snow cover albedo, and microroughness of the ski running surface are analyzed in detail. [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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This paper proposes a Topology Optimization (TO) method for the design of microstructures within All-Solid-State Batteries (ASSBs), using the homogenization method. ASSBs have attracted significant attention because of their possibilities to surpass the problems of conventional liquid lithium-ion batteries regarding safety, energy density, and longevity. To improve the performance of ASSBs, many experimental research results based on costly trial-and-error approaches have previously been presented. In order to mitigate the cost and time involved in trial-and-error, several numerical approaches have also been proposed to deal with the multiple materials in various batteries. TO is one of the most flexible structural optimization methods that can allow topological changes as well as boundary changes, and has the potential to provide high-performance structures. TO methods have also been successfully applied to the design of several kinds of batteries, such as Solid Oxide Fuel Cells (SOFC) and Redox flow batteries. However, to the best of our knowledge, research concerning the structural optimization of ASSBs has not been found. In this paper, we propose the TO method targeting microstructure designs of ASSBs using the homogenization method to associate microstructural configurations and macroscopic properties. First, we define a new objective function that can appropriately evaluate the performance of ASSBs and can reduce computational costs in the optimization process. Next, the design sensitivities addressing the time-dependent and nonlinear aspects of the problem are derived using the Lagrange and continuous adjoint methods. Finally, we provide several numerical results under various conditions, including different C-rates, to confirm the validity and efficiency of our proposed method. [ABSTRACT FROM AUTHOR]

In recent years, individuals have begun to pay more attention to non-traditional stabilizers due to the problems connected with traditional stabilizers. Traditional stabilizers have undergone extensive investigation, and the mechanisms by which they act are well understood. This paper presents findings of the effect of sugarcane vinasse wastewater (VI) and sodium alginate (SA) polymer on the compressibility behavior, and microstructural evolution of clay soil using mixing method. The premise of this paper is to eliminate waste material from nature and compare the performance of this material against the use of polymers that have recently been used in improvement. The additives were dissolved in water and then introduced to the dried stratified soil to produce improved soil samples using the mixing technique. Transported unconfined compressive strength (UCS) was examined for 1, 14, and 28 days of treatments with additive ranges of 3–15% for VI and 0.25–1.25% for SA. In clay with high plasticity, the findings show that VI significantly influences increasing the UCS. With the addition of 9% vinasse to the soil at the age of 28 days, the UCS has increased by 78.8%. Additionally, the introduction of 1.25% SA to the soil has increased by 261.9% for the 28-day treatment efficiency significantly. Microstructural and chemical examination revealed that the mineralogical and morphological contents of the stabilized soil were influenced due to the pozzolanic reaction. The results showed that waste by-product liquid was able to significantly increase the strength and compressibility of the clay soil. Using a large volume of waste by-product liquid to stabilize soil, the researchers discovered a straightforward application method. [ABSTRACT FROM AUTHOR]

The coaxial laser-plasma hybrid welding provides a novel method for the composition of two heat sources and achieves gently transitional butt joints with wider upper surfaces. The influence of hybrid welding parameters on the weld appearance and composite plasma behaviors had been proved with a significant composite heat source effect previously; the effect of microstructure on its mechanical properties has been investigated and explored in this paper. Finite element computation based on temperature field simulation is conducted to shed more light on the heat distribution characteristics of this novel hybrid welding method. The temperature in the hybrid-dominated region is much higher than that in the laser-dominated region. The tensile strength of the hybrid welded joints is higher than the standard requirement of base metal, and fractured at the base metal with an obvious necking, indicating as ductile fracture. The nanohardness results show the hardness rank order of the weld zone, heat-affected zone and base metal. It is revealed that the grain refinement of acicular α' martensite and fine αg particles, the increase of distribution of the geometric necessary dislocations and the large angle grain boundary proportion in the weld zone contribute to an increase in hardness, tensile strength of the hybrid welded joint of Ti–6Al–4V. It also discloses the reason why the tensile fracture location is on the base metal. This work provides a theoretical and practical basis for the application of thin titanium alloy welding, especially at high welding speed. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing is revolutionizing how we produce and use materials. Selective Laser Melting (SLM) is one of the most popular additive manufacturing techniques for creating high-performance metal components. Stainless Steel is preferred for additive manufacturing due to its powder form availability, low cost, mechanical properties, and corrosion resistance. However, the complex thermal history and rapid solidification in the SLM process led to an out-of-equilibrium microstructure of resulting components, which can affect their mechanical properties. To better understand the relationship between processing, microstructure, and properties, exploring and enhancing SLM-fabricated stainless-steel components is essential. This review comprehensively overviews the selective laser melting process, key processing parameters, and commonly encountered defects. Furthermore, the study presents a detailed discussion of microstructure, mechanical behavior (including hardness, tensile, and fatigue properties), and corrosion resistance of all SLM-manufactured stainless steel grades, along with the effects of various post-process treatments. This paper reveals that the SLM process can produce stainless steel with satisfactory performance that may exceed conventionally processed materials. However, the final section highlights the challenges and research gaps in this field that must be addressed. [ABSTRACT FROM AUTHOR]

In this paper, the preparation of pre-alloyed powder and its effect on the properties of metal-bonded diamond tools were systematically studied. A co-precipitation process was used to prepare ultra-fine quaternary Cu-based pre-alloyed powder. The optimal parameters of preparing the precursor powder were precipitation temperature of 50 ℃ and reactant concentration of 1 mol/L. After the precursor powder was calcined and reduced by hydrogen, ultra-fine Cu-based pre-alloyed powder with an average particle size of about 0.55 μm was obtained and its main components were Cu, Fe, Ni, Cu–Sn, and Fe3Ni2. Furthermore, the mechanical properties of the bulks with pre-alloyed powders and the elemental metal powder mixture of equivalent composition were investigated. The results demonstrated that the mechanical properties of sintered bulks, including relative density, hardness and flexural strength, were improved using pre-alloyed powder. The optimal hardness and flexural strength values of the bulks with pre-alloyed powder were 110 HRB and 1056 MPa, respectively, which were 10.0% and 24.8% higher than those of the mixed powder matrix (100 HRB and 846 MPa). With the addition of diamond particles, the maximum flexural strength of the bulks reduced to 882 MPa, which was still 24.1% higher compared to the mixed powder matrix (711 MPa). In addition, the cutting ability of the diamond saw blade with pre-alloyed powder was superior to that with the elemental metal mechanical mixing powder. [ABSTRACT FROM AUTHOR]

In this paper, the Hadfield steel matrix composite reinforced with dispersed high chromium cast iron (HCCI) was prepared by using the hot-rolling forming method. The microstructure and mechanical properties of the bimetal composites were analyzed. The experimental results showed that the brittle HCCI was necked and broken into uneven blocks or particles after hot-rolling deformation. The fractured hard HCCI was encased in Hadfield steel to form HCCI-reinforced Hadfield steel composite. Hot rolling results in good metallurgical bonding of the two metals, and Mn, Cr, Fe and Si elements were diffused at the interface. The wear property of the composite was higher than that of Hadfield steel. The hard HCCI played an important role in protecting the Hadfield steel matrix from wearing. The average impact toughness of the composite reached 38.2 J cm−2. The impact property of the composite was between Hadfield steel and HCCI, but significantly higher than that of as-cast iron. [ABSTRACT FROM AUTHOR]

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]

As an industrially reliable, controllable and effective deformation technique, friction stir process (FSP) can significantly refine the grain size, effectively activate prismatic plane and pyramidal plane slip systems of wrought magnesium alloys through intense plastic deformation and grain refinement, improving the mechanical properties and plasticity simultaneously. Therefore, more and more researchers are devoted to revealing the relationship between grain size, morphology and distribution of precipitated phases, and texture modification with the mechanical properties of magnesium alloys after FSP by means of some characterization techniques, such as electron backscattering diffraction, scanning electron microscopy and transmission electron microscopy. In this paper, the research results of FSP in wrought magnesium alloys in the last five years are reviewed. The fundamental principle and advantages of the FSP process are introduced, and the effects of the FSP process parameters and tool size on the microstructure characteristics, textile evolution, dynamic recrystallization mechanism and mechanical properties of Mg–Al–Zn, Mg–Li and Mg–Zn–Zr wrought magnesium alloys are analyzed emphatically. The preparation of ultrafine crystalline microstructures and achievement of superplastic behavior by modification of FSP are discussed in classification. In addition, the current status of metal additive manufacturing processes based on stirred friction processing (such as friction stir additive manufacturing and additive friction stir deposition) in wrought magnesium alloys is discussed in detail. Finally, the future research development and application of FSP in wrought magnesium alloys are prospected. Some reasonable suggestions are put forward to address the existing problems at this stage, which can provide references for further research in the future. [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]

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]

Mg-Zn-Ca-Mn series alloys are developed as promising candidates of 5G communication devices with excellent thermal conductivities, great ductility, and acceptable strength. In present paper, Mg-xZn-0.4Ca-0.2Mn (x = 2wt%, 4wt%, 6wt%) alloys were prepared by a near-solidus extrusion and the effect of Zn content on mechanical and thermal properties were investigated. The results showed that the addition of minor Ca led to the formation of Ca2Mg6Zn3 eutectic phase at grain boundaries. A type of bimodal microstructure occurred in the as-extruded alloys, where elongated coarse deformed grains were embedded in refined recrystallized grains matrix. Correspondingly, both yield strength and ductility of the alloys were significantly enhanced after extrusion due to the great grain refinement. Specially, higher Zn content led to the increment in yield strength and a slight reduction in elongation due to the larger fractions of second phase particles. The room temperature thermal conductivity of as-extruded alloys was also improved compared with that of as-cast counterparts. The increment of Zn content decreased the thermal conductivity of both as-cast and as-extruded alloys, which was due to the increased second phase fraction and solution atoms in the matrix, that hindering the motion of electrons. The as-extruded Mg-2Zn-0.4Ca-0.2Mn (wt%) alloy exhibited the highest elongation of 27.7% and thermal conductivity of 139.2 W/(mK), combined with an acceptable ultimate tensile strength of 244.0 MPa. The present paper provides scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity. [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]

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]

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]

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]

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]

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]

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]

Additive manufacturing (AM) is an established manufacturing technology which allows for greater design freedom. Across the seven existing AM processes, we observe a variety of defects in printed parts, due to the different physical properties of each manufacturing process. This variety of defects complicates the design step without a clear overview of the deep interaction geometry-process-defect. The classification of these defects, which may be process- or machine-based, often raises methodological and terminological issues. In this paper, a review of AM general part defects using a process-based approach, is proposed. The aim of this paper is to provide the designer with a classification that would allow to make choices in the part design, by taking stock of the different defects affecting the resulting part considering the chosen process. For each process category defined in ISO/ASTM 52900, the main properties and defects of parts are reviewed and classified into four families: geometry and dimensions, surface quality, microstructure and mechanical properties. This review focuses in particular, on the process parameters which affect declined defects and properties allowing a relevant choice of the designer with respect to the process or the expected requirements of the part. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the effect of high viscosity petroleum resin (HV-PR) on the microstructure and macro properties of styrene–butadiene–styrene block copolymer (SBS) modified bitumen. SBS modified bitumen was prepared with different content of HV-PR in this paper. The microscopic images were obtained by fluorescence microscope and were analyzed qualitatively and quantitatively with MATLAB and image-pro software. The dynamic shear rheometer test was used to study the dynamic shear properties of SBS modified bitumen with different HV-PR content. The effect of different HV-PR content on the aging resistance of the modified bitumen was studied. The other technical properties of SBS modified bitumen with different HV-PR content, such as segregation softening point difference etc. were also tested. The research results show that: HV-PR can help SBS to be sheared into smaller particles during the shearing process, effectively improve the swelling degree of SBS modifier, improve the spatial distribution of cross-linking structure, and form a more compact cross-linking structure. The addition of HV-PR can effectively improve the high-temperature deformation resistance and fatigue damage resistance of SBS modified bitumen, the higher the HV-PR content, the more obvious the improvement effect. The addition of HV-PR can also significantly reduce the loss of ductility and the gain of viscosity of SBS modified bitumen during the long-term aging process. The higher the HV-PR content, the more significant the effect. HV-PR can effectively improve the viscosity, low-temperature performance, and storage stability of bitumen. [ABSTRACT FROM AUTHOR]

Effective diffusion is an important macroscopic property for assessing transport in porous media. Numerical computations on segmented 3D CT images yield precise estimates for diffusive properties. On the other hand, geometrical descriptors of pore space such as porosity, specific surface area and further transport-related descriptors can be easily computed from 3D CT images and are closely linked to diffusion processes. However, the investigation of quantitative relationships between these descriptors and diffusive properties for a diverse range of porous structures is still ongoing. In the present paper, we consider three different soil samples of each loam and sand for a total of six samples, whose 3D microstructure is quantitatively investigated using univariate as well as bivariate probability distributions of geometrical pore space descriptors. This information is used for investigating microstructure–property relationships by means of empirically derived regression formulas, where a particular focus is put on the differences between loam and sand samples. Due to the analytical nature of these formulas, it is possible to obtain a deeper understanding for the relationship between the 3D pore space morphology and the resulting diffusive properties. In particular, it is shown that formulas existing so far in the literature for predicting soil gas diffusion can be significantly improved by incorporating further geometrical descriptors such as geodesic tortuosity, chord lengths, or constrictivity of the pore space. The robustness of these formulas is investigated by fitting the regression parameters on different data sets as well as by applying the empirically derived regression formulas to data that is not used for model fitting. Among others, it turns out that a formula based on porosity as well as mean and standard deviation of geodesic tortuosity performs best with regard to the coefficient of determination and the mean absolute percentage error. Moreover, it is shown that regarding the prediction of diffusive properties the concept of geodesic tortuosity is superior to geometric tortuosity, where the latter is based on the creation of a skeleton of the pore space. [ABSTRACT FROM AUTHOR]

Oscillating laser-assisted plasma transfer arc (Laser-PTA) additive manufacturing technology using coaxial feeding powder was proposed in this paper. To improve the surface accuracy, microstructure and mechanical properties of the formed thin-walled structure, a transverse linear scanning path laser beam oscillation (LBO) process was used. Considering that the interlaminar region is the weak region of the multilayer additive manufacturing structure, this paper focused on the influence of the laser scanning speed on the microstructure and mechanical properties of the interlaminar region. The results show that compared with Laser-PTA process, the LBO process improved the surface accuracy of the formed structure, and achieved shorter and finer dendrite growth morphologies. In particular, the LBO process with high laser scanning speed had a positive influence on the geometric dislocation density and high angle grain boundary in the interlaminar region, which improved the plasticity of the interlaminar region. In addition, the LBO process with high laser scanning speed reduced the 〈111〉 and 〈101〉 crystallographic textures and improved the strength of the interlaminar region. The optimization of the microstructure in the interlaminar region had a favorable effect on the overall mechanical properties of the thin-walled structure, and the tensile test results showed that the LBO process with high laser scanning speed significantly improved the ultimate tensile strength and elongation in the vertical and horizontal directions. [ABSTRACT FROM AUTHOR]

Water retention is an important soil property affecting the hydro-mechanical behavior of unsaturated soils. This study investigated the water retention property and the microstructure of lime-treated Ili loess from Xinjiang in China. Such material is a typical central Asian loess characterized by high salt content and strong collapsibility. The matric suction and total suction were measured by the filter paper method and saturated salt solution method. The microstructure characteristics of untreated and lime-treated loess were analyzed by scanning electron microscopy and mercury intrusion porosimetry, and the influence of the microstructure variation on the macroscopic water retention property was analyzed by introducing the parameter of fractal dimension, which is commonly used to describe the characteristic of pore shape and size. Results showed that, along the curing time, the lime treatment induced a change of the soil microstructure in terms of pore distribution with a consequent increase of the matric suction and overall water retention capacity. However, the osmotic suction decreased during curing. During curing, the lime treatment reduced the percentage of macro-pores and increased the nano-pores. Then, the soil microstructure was characterized by the fractal dimension, which increased with the curing times. Finally, the proposed fitting model of water retention consisting in introducing the fractal dimension into the Van-Genuchten model appeared adequate with good accuracy. [ABSTRACT FROM AUTHOR]

In materials science, machine learning has been intensively researched and used in various applications. However, it is still far from achieving intelligence comparable to that of human experts in terms of creativity and explainability. In this paper, we investigate whether machine learning can acquire explainable knowledge without directly introducing problem-specific information such as explicit physical mechanisms. In particular, a potential of machine learning to obtain the capability to identify a part of material structures that critically affects a physical property without human prior knowledge is mainly discussed. The guide for constructing the machine learning framework adopted in this paper is to imitate human researchers' process of thinking in the interpretation and development of materials. Our framework was applied to the optimization of structures of artificial dual-phase steels in terms of a fracture property. A comparison of results of the framework with those of numerical simulation based on governing physical laws demonstrated the potential of our framework for the identification of a part of microstructures critically affecting the target property. Consequently, this implies that our framework can implicitly acquire an intuition in a similar way that human researchers empirically attain the general strategy for material design consistent with the physical background. [ABSTRACT FROM AUTHOR]

The paper presents the results of the electron microscopic microstructural study of a laboratory sample of a fibrous composite material. The resulting cross-sectional cut image of the sample was processed using software programs working with vector and raster file formats. The fiber cross-sectional cut areas, obtained in a vector graphical program, were compared with the areas calculated at various stages of the image preparation for evaluating the fiber cross-sectional cut area in a raster format. As a result, black-and-white shade adjustment modes, ensuring rapid and high-accuracy graphic processing of the fibrous material microstructure, were selected. The error of calculating the fiber cross-sectional cut area was in the limits of 1%, while the processing time reduced by tens of hours depending on the number of measured objects. [ABSTRACT FROM AUTHOR]