Microstructure Formation Research Articles

Influence of Y2O3 Nano-Dispersoids on the Characteristics of AlCoCrFeNi2.1-Reinforced Tungsten Alloys via Mechanical Alloying and Low-Temperature Sintering

This study investigates the effects of nano-oxide dispersoids on microstructural evolution, phase formation, and mechanical properties of W-Mo-Ti alloys reinforced with AlCoCrFeNi2.1 during mechanical alloying. An EBSD/EDS analysis confirmed the formation of different phases, including the tungsten matrix, FCC reinforcement phase, Al2O3, and (Al,Cr) oxide. Y2O3 particles played a crucial role in refining the microstructure, promoting a uniform dispersion of the reinforcement phase and oxide particles in the tungsten model alloys. Mechanical testing demonstrates that the Y2O3-containing alloy exhibits improved hardness with prolonged milling, attributed to the refinement in the microstructure. In contrast, the Y2O3-free alloy shows reduced hardness due to the agglomeration of reinforcement phases surrounded by an (Al,Cr) oxide layer. The model tungsten alloys exhibit brittle behavior in compression tests, which can be attributed to the presence of (Al,Cr) oxide layers weakening the interfacial bonding and limiting plastic deformation.

Microstructure formation mechanism of Mo2C/W2C/Mo2C three-layer film on Mo substrate prepared by magnetron sputtering and carburization

Microstructure formation mechanism of Mo2C/W2C/Mo2C three-layer film on Mo substrate prepared by magnetron sputtering and carburization

Hot-Pressing of Ti-Al-N Multiphase Composite: Microstructure and Properties

This study focuses on the development and characterization of a bulk Ti-Al-N multiphase composite enriched with BN addition and sintered through hot pressing. The research aimed to create a material with optimized mechanical and corrosion-resistant properties suitable for demanding industrial applications. The composite was synthesized using a powder metallurgy approach with a mixture of AlN, TiN, and BN powders, processed under a high temperature and pressure. Comprehensive analyses, including microstructural evaluation, hardness testing, X-ray tomography, and electrochemical corrosion assessments, were conducted. The results confirmed the formation of a multiphase microstructure consisting of TiN, Ti₂AlN and Ti₃AlN phases. The microstructure was uniform with minimal porosity, achieving a hardness within the range of 500–540 HV2. Electrochemical tests revealed the formation of a passive oxide layer that provided moderate corrosion resistance in chloride-rich environment. However, localized pitting corrosion was observed under extreme conditions. The study highlights the potential of a BN admixture to enhance mechanical and corrosion-resistant properties and suggests directions for further optimization in sintering processes and material formulations.

A comprehensive report of the clinical and mutational profiles of 30 Iranian malignant infantile osteopetrosis patients.

Osteopetrosis is a group of genetically and clinically diverse inherited disorders characterized by an increase in bone density. The main known cause is an abnormality in the development or function of osteoclasts. Hence, the process of bone resorption is impaired, resulting in: 1- a reduction in bone marrow volume and, subsequently, a decrement in the hematopoietic capacity of bone marrow, which leads to anemia and compromised immunological function; 2- improper bone development, which leads to pressure on peripheral nerves, causing auditory, visual, and movement impairments; and 3- disturbance in the formation of bone microstructure that leads to susceptibility to bone fracture. This study aimed to evaluate the clinical symptoms and genetic causes of 30 patients (probands) who suffered from malignant infantile osteopetrosis, a subtype of this disorder. The Sanger sequencing technique was used to sequence four common genes (TCIRG1, CLCN7, SNX10, and OSTM1) in osteopetrosis. Subsequently, the selected variants were subjected to segregation analysis between the probands and their parents. Consequently, the sequencing of these four genes in probands revealed 16 pathogenic and likely pathogenic mutations, five of which had never been reported before. The TCIRG1 gene has three novel splice site variations and one frameshift variant. The CLCN7 gene had a novel missense variant. Also, a total of five variants of uncertain significance (VUSs) were identified in the analyzed sequences, of which three haven't been reported to date, and two were observed in osteopetrosis patients. Therefore, by documenting these novel likely pathogenic variants and VUS in known genes associated with this disease in patients, specialists can conduct more accurate genetic analysis and counseling when encountering these variants. Additionally, this documentation will facilitate the reclassification of these variants.

A preliminary exvivo diffusion tensor imaging study of distinct aortic morphologies.

Changes in the microstructure of the aortic wall precede the progression of various aortic pathologies, including aneurysms and dissection. Current clinical decisions with regards to surgical planning and/or radiological intervention are guided by geometric features, such as aortic diameter, since clinical imaging lacks tissue microstructural information. The aim of this proof-of-concept work is to investigate a non-invasive imaging method, diffusion tensor imaging (DTI), in exvivo aortic tissue to gain insights into the microstructure. This study examines healthy, aneurysm and a type B chronic dissection aortae, via DTI. DTI-derived metrics, such as the fractional anisotropy, mean diffusivity, helical angle and tractography, were examined in each morphology. The results from this work highlighted distinct differences in fractional anisotropy (healthy, 0.24 ± 0.008; aneurysmal, 0.19 ± 0.002; dissected, 0.13 ± 0.006) and a larger variation in the helical angle in the dissected aorta compared to healthy (39.28 ± 11.93° vs. 26.12 ± 4.60°, respectively). These differences were validated by histological characterisation. This study demonstrates the sensitivity of DTI to pathological changes in aortic tissue, highlighting the potential of this methodology to provide improved clinical insight.

Targeted Minimum Quantity Fluid Application in Machining

The surface integrity of a machined component is crucial for its service life part. One of the main final specifications that a machined part is inspected for is the surface integrity metrics, including surface residual stresses, surface microhardness, surface roughness, and microstructure. In this paper, the cutting fluid is strategically targeted to utilize heat energy effectively in the primary, secondary, and tertiary shear zones to positively affect the surface integrity metrics and machining mechanics. In this study, a lower quantity of the cutting fluids is targeted at the high-temperature zones to reduce the machining temperatures, thereby effectively simulating the effect of a ‘flood coolant’. The cutting fluid is applied simultaneously as a targeted Minimum Quantity Fluid (MQF) on the cutting tool’s flank and rake faces to improve the surface integrity metrics and chip formation. Also, this study analyzes the effect of the cutting fluid composition, the type of cutting fluid, and the amount of fluid quantities. The machining-induced surface integrity metrics are analyzed to understand the effects of targeted minimum quantity fluid application. The impact of the targeted application of cutting fluid on machining mechanics metrics, such as cutting forces and chip formation, is analyzed. Applying a targeted MQF application at the flank face of the cutting tool leads to higher compressive subsurface principal residual stresses. The results indicate that using MQF on both the flank and rake faces simultaneously enhances the surface integrity. The effect of a cutting fluid jet on the flank face is modeled to highlight the thermophysical properties that are crucial for selecting the appropriate cutting fluid to lower the machining-induced temperatures. With targeted MQF application, the fluid jet acts as a dynamic and external chip control mechanism. Overall, effectively managing temperatures in machining could enhance subsurface residual stresses and surface roughness using various cutting fluid combinations. Also, this paper presents a targeted cutting fluid application that improves the microstructural formation, enhancing chip control and producing machined surfaces and components with better surface integrity.

Development of a Finite Element Model for the HAZ Temperature Field in Longitudinal Welding of Pipeline Steel

In this study, a novel hybrid heat source model was developed to simulate the welding temperature field in the heat-affected zone (HAZ) of X80 pipeline steel. This model replicates welding conditions with high accuracy and allows flexible three-dimensional adjustments to suit various scenarios. Its development involved the innovative integration of microstructural crystallography information with a multi-scale calibration and validation methodology. The methodology focused on three critical aspects: the weld interface morphology, the location of the Ac1 temperature, and the size of prior austenite grains (PAG). The morphology of the weld interface was calibrated to align closely with experimental observations. The model’s prediction of the Ac1 location in actual welded joints exhibited a deviation of less than ±0.3 mm. Furthermore, comparisons of reconstructed PAG sizes between thermal simulation samples and actual HAZ samples revealed minimal discrepancies (5 μm). Validation results confirmed that the calibrated model accurately describes the welding temperature field, with reconstructed PAG size differences between simulation and experimental results being less than 9 μm. These findings validate the accuracy of the calibrated model in predicting welding temperature fields. This research introduces a novel framework for the development of heat source models, offering a robust foundation for improving welding performance and controlling microstructure in different regions during the welding process of high-strength low-alloy (HSLA) steel.

SHELL MICROSTRUCTURE AND MINERALOGY OF THE MOLLUSC SPECIES <em>ANADARA UROPIGIMELANA</em> (BORY DE SAINT-VINCENT, 1827), <em>TIVELA STEFANINII</em> (NARDINI, 1933) AND <em>OLIVA BULBOSA</em> (RÖDING, 1798)

Mollusc shells are composite structures made of calcite and/or aragonite crystals and biopolymers, arranged in a great variety of microstructures. The formation of shell microstructures is affected by environmental and physiological factors and differences among microstructural types are believed to be of phylogenetic and adaptive biomechanical significance. Here, we characterise and illustrate for the first time, through SEM and XRD analyses, the shell microstructure and mineralogy of specimens of the bivalves Anadara uropigimelana (Bory de Saint-Vincent, 1827) and Tivela stefaninii (Nardini, 1933), and of the gastropod Oliva bulbosa (Röding, 1798), collected in the Upper Holocene HAS1 settlement and in a shell midden in the Khor Rori Archaeological Park (Oman). Anadara uropigimelana shows an aragonitic shell with an outer crossed lamellar layer, an inner complex crossed lamellar layer and an irregular simple prismatic pallial myostracum; periodic bands of dendritic nondenticular composite prisms occur in the outer part of the outer layer, reflecting seasonal changes in water temperatures and growth rates. Shells of Tivela stefaninii are aragonitic with an outer composite prismatic layer, a middle crossed lamellar layer and an inner complex crossed lamellar layer, whereas those of Oliva bulbosa are characterised by an irregular alternation of aragonitic crossed lamellar layers; a transitional layer defined by the occurrence of tidally controlled growth lines, a crossed lamellar callus and a myostracal layer are also described are also described in Oliva bulbosa. With this investigation, we provide novel microstructural and mineralogical data on these poorly known mollusc species, providing useful characters for phylogenetic, evolutionary, crystallographic, and palaeoenvironmental studies.

Fabrication of three-layered aluminium-copper laminated composites using friction stir additive manufacturing

Abstract The current study employed the friction stir additive manufacturing (FSAM) method to fabricate three-layered laminated composite by utilizing 3 mm thick sheets of AA6061-T6 alloy (top and bottom layers) and pure Cu (middle layer). The feasibility of FSAM in producing high-performance Al/Cu/Al laminated composites was evaluated by analyzing the influence of tool rotational speed on the microstructure and mechanical properties. The composites were fabricated at rotational speeds of 900 rpm, 1200 rpm, and 1500 rpm; maintaining a traverse speed of 90 mm min−1 throughout the experiments. Changes in the weld morphology, macrostructure, microstructure, and intermetallic formation were noted and analyzed. The findings indicated that achieving macro defect-free joints is possible with a rotational speed of 1200 rpm. Detailed examinations via electron dispersive spectrum and x-ray diffraction revealed the presence of AlCu, Al2Cu and Al2Cu3 intermetallic compounds within the nugget zone. Significantly varied microhardness levels ranging from 59.4 to 143.7 HV0.1 were observed, corresponding to distinct microstructural features within the processed zone. The Al/Cu laminated composite exhibited an excellent combination of strength and ductility; a UTS of 214.6 MPa and an elongation of 23.4%. The findings showcase that utilizing FSAM presents an exceptional opportunity to fabricate novel Al/Cu multilayered composites with distinctive mechanical properties.

Engineering performance and environmental assessment of sustainable concrete incorporating nano silica and metakaolin as cementitious materials

The carbon footprint associated with cement production, coupled with depletion of natural resources and climate change, underscores the need for sustainable alternatives. This study explores the effect of metakaolin (MK) and nano-silica (NS) on concrete’s engineering performance and environmental impact. Initially, compressive, tensile, and flexural strength tests, along with durability assessments like water absorption, sorptivity, rapid chloride permeability, and resistance to acid and sulphate attacks, were conducted. Later, X-ray Diffraction spectroscopy and Field-emission scanning electron microscopy were employed for microstructural analysis. Subsequently, the environmental impact of micro and nano materials was assessed using embodied carbon emissions and eco-strength efficiency. The results revealed that the hybrid mixes of 12.50% MK and 2% NS (M7) showed superior performance, demonstrating significant strength enhancements and eco-efficiency, achieving 0.15 MPa/kg CO2/m3 at 28th day. Meanwhile, the MK-only mix (M6) yielded the lowest embodied CO2 emissions at 330 kg CO2/m3. MK and NS effectively reduce porosity and enhance durability against environmental factors while lowering clinker content, contributing to sustainability. Furthermore, the microstructural behaviour showed early hydration, dense microstructure and additional Calcium Silicate Hydrate formation, leading to improved properties. The outcomes reveal that the concrete configuration has altered at micro and nano levels by the inclusion of MK and NS, demonstrating their substantial contribution to producing environmentally friendly, effective, and beneficial concrete.

Construction of brain age models based on structural and white matter information.

Brain aging is an inevitable process in adulthood, yet there is a lack of objective measures to accurately assess its extent. This study aims to develop brain age prediction model using magnetic resonance imaging (MRI), which includes structural information of gray matter and integrity information of white matter microstructure. Multiparameter MRI was performed on two population cohorts. We collected structural MRI data from T1- and T2-sequences, including gray matter volume, surface area, and thickness in different areas. For diffusion tensor imaging (DTI), we derived four white matter parameters: fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. To achieve reliable brain age prediction based on structure and white matter integrity, we employed LASSO regression. We successfully constructed a brain age prediction model based on multiparameter brain MRI (Mean absolute error of 3.87). Using structural and diffusion metrics, we identified and visualized which brain areas were notably involved in brain aging. Simultaneously, we discovered that lateralization during brain aging is a significant factor in brain aging models. We have successfully developed a brain age estimation model utilizing white matter and gray matter metrics, which exhibits minimal errors and is suitable for adults.

Investigation of Microstructure and Hot Crack Formation Mechanisms in the Heat-Affected Zone of GTAW-Repaired Cast K4002 Nickel-Based Superalloy with HGH3113 Filler Metal

Investigation of Microstructure and Hot Crack Formation Mechanisms in the Heat-Affected Zone of GTAW-Repaired Cast K4002 Nickel-Based Superalloy with HGH3113 Filler Metal

Controlling the formation of microstructure at the melt-pool boundaries during directed energy deposition of aluminum alloy with a modified continuous growth restriction factor

Controlling the formation of microstructure at the melt-pool boundaries during directed energy deposition of aluminum alloy with a modified continuous growth restriction factor

The Effect of CaCl2 on the Gelling Properties of Pea Protein-Pectin Dispersions.

The effects of CaCl2 addition before (PreCa) or after (PostCa) heating pea protein-pectin dispersions on the formed gel's rheological and microstructural properties were investigated. Isothermal titration calorimetry (ITC) revealed that CaCl2 bound both pea proteins and pectins through a spontaneous exothermic reaction and pectin exhibited a stronger binding affinity to CaCl2. In PreCa gels, low levels of CaCl2 (5 and 10 mM) increased the gel elasticity (increase in the storage modulus, G') and their microstructural compactness. However, higher CaCl2 levels (15 and 25 mM) decreased gels' elasticity, likely due to diminished hydrogen bonds formed in the cooling stage, resulting in gels with larger voids and fewer interconnections between the protein and pectin phases. In PostCa gels, their elasticity increased with the CaCl2 content, a rheological change associated with the formation of denser microstructures. The addition of 25 mM CaCl2 decreased β-sheet and increased α-helix and random coil structures. Hydrogen bonding and electrostatic and hydrophobic interactions contributed to gel formation and stability in both PreCa and PostCa gels, whereas disulfide bonds had negligible effects. This study highlights the role of CaCl2 in modulating pea protein-pectin gels' properties and microstructures for the development of gel-like foods with diverse textures and mouthfeels.

Helical Surface Relief Formation by Two-Photon Polymerization Reaction Using a Femtosecond Optical Vortex Beam.

Optical vortices possess a helical phase wavefront with central phase dislocation and orbital angular momentum. We demonstrated three-dimensional microstructure formation using a femtosecond optical vortex beam. Two-photon polymerization of photocurable resin was induced by long-term exposure, resulting in the fabrication of cylindrical structures. The ring shape represents the intensity profile of optical vortex beam, and the diameter and height of the structures are related to the laser power. Periodic helical surface relief was observed on the inner surface. Significantly, the helical direction of the surface relief is consistent with the direction in which the orbital angular momentum acts and changes depending on the sign of the topological charge. Our proposed method can form three-dimensional microstructures with helical periodic surface relief, and the pitch is smaller than the diffraction limit without laser scanning. This method paves the way for further applications in optical devices such as three-dimensional chiral metamaterials.

Microstructure Formation and Dry Reciprocating Sliding Wear Response of High-Entropy Hypereutectic White Cast Irons

White cast irons (WCI) are widely used in industries requiring high wear resistance due to their microstructure consisting of hard carbides dispersed within a metallic matrix. This study focuses on developing wear-resistant multi-component hypereutectic high chromium cast irons, merging concepts of high entropy alloys with the conventional metallurgy of white cast irons, specifically exploring the influence of carbide-forming elements such as V, Mo, and Ni on solidification behavior, microstructure, and wear performance. The research investigates the solidification process of the alloys using Computer-Aided Cooling Curve Analysis (CA-CCA) and characterizes the microstructures through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wear behavior of the developed alloys is evaluated through reciprocating sliding wear tests, revealing the impact of varying chemical compositions on wear resistance. The results demonstrate that high-entropy white cast iron (HEWCI), particularly those enriched with carbide-forming elements, exhibit superior abrasion resistance compared to conventional high-chromium cast irons. The alloy with 2 Mo and 4 V content showed the best performance, presenting the lowest wear rate (61.5% lower than HCCI alloy) and CoF (values ranging from 0.20 to 0.22) due to the highest concentration of V carbides.

Investigations into metallurgical, mechanical, and particulate matter emissions in in situ micropowder alloyed wire arc additive manufacturing process

Wire Arc Additive Manufacturing (WAAM) is an advanced manufacturing technique capable of a high deposition rate and is used for fabricating large-sized and complex components. Of specific interest in the recent past is the in-situ micropowder alloying during filler material deposition to modify the properties of each deposited layer. This study focuses on investigating the metallurgical and mechanical characteristics of the steel produced through powder-added WAAM, using characterization techniques such as optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy and Vickers microhardness testing. Additionally, changes in the size distribution of fine and ultrafine particles (UFP) emitted during WAAM deposition, with and without micropowder addition, were studied using a Scanning-Mobility-Particle-Sizer. Two single-bead multi-layered walls of ER70S6 were deposited in two conditions: as-deposited steel wall and interlayer Titanium micropowder-added steel wall. The results indicate that the microhardness of the Ti micropowder-added steel wall increased by approximately 35% due to the formation of specific microstructures, such as bainitic-ferrite, with retained austenite and mainly due to precipitation strengthening. The emission measurement results suggest that the addition of Ti micropowder during WAAM increases UFP concentration by 20%. The elevated temperature during the deposition process could be a key factor for the rise in particulate matter emissions.

Microstructure Formation in Hypoeutectic Alloys in the Fe–C–B–Cr–W System

This work investigates the influence of tungsten (W) on the microstructure of alloys in the system Fe–C–B–Cr. The main goal is to examine the effect of W-additions on the microstructure and especially the potential stabilization of primary or eutectic borides in alloys with the compositions of Fe–0.4C–1B–2.5Cr + W. Thermodynamic equilibrium and Scheil–Gulliver calculations are performed to identify microstructurally significant alloy-compositions which are also devoid of borocarbides at austenitizing temperature. Accordingly, laboratory melts are cast, samples are swaged, austenitized, quenched and tempered. Additionaly, a near-equilibrium state is created by a diffusion annealing step to validate the equilibrium calculation. The resulting microstructures are characterized by X-ray diffraction, scanning electron microscopy. It is shown that swaging can effectively convert the eutectic network into a powder-metallurgical-like spherical and isotropic hard phase dispersion without introducing microscopic or macroscopic defects. W-additions lead to the stabilization of eutectic FeWB and B-rich M23(B,C)6 carboborides as opposed to C-rich M23(C,B)6 formed in the quarternary Fe–C–B–Cr system. Thus, the chemical binding of B in M23(B,C)6 leads to a significant destabilization of the M2B-type borides FeWB and (Fe,Cr)2B. The results show that W-addition strongly influences the solidification reaction of Fe–Cr–C–B–W alloys and thus the present phases, even after diffusion annealing.

An Ultra-Stable Polysaccharide Gel Plugging Agent for Water Shutoff in Mature Oil Reservoirs

Polyacrylamide-based gel plugging agents are extensively utilized in oilfields for water shutoff. However, their thermal stability, salt tolerance, and shear resistance are limited, making it difficult to achieve high-strength plugging and maintain stability under high-temperature and high-salinity reservoir conditions. This study proposes the use of chitosan (CTSs), a polysaccharide with a rigid cyclic structure, as the polymer. The organic cross-linker N,N′-methylenebisacrylamide (MBA) is incorporated via the Michael addition reaction mechanism to develop an ultra-stable, organically cross-linked chitosan gel system. The CTS/MBA gel system was evaluated under various environmental conditions using rheological testing and thermal aging to assess gel strength and stability. The results demonstrate significant improvements in gel strength and stability at high temperatures (up to 120 °C) and under high-shear conditions, as the increased cross-linking density enhanced resistance to thermal and mechanical degradation. Rapid gelation was observed with increasing MBA concentration, while pH and salinity further modulated gel properties. Scanning electron microscopy revealed the formation of a three-dimensional microstructure after gelation, which contributed to the enhanced properties. This study provides novel insights into optimizing polymer gel performance for the petroleum industry, particularly in high-temperature and high-shear environments.

An Impact of Prolonged Electrolysis on the Electrochemical Performance and Surface Characteristics of NiFe-Modified Graphite Electrodes for Alkaline Water Electrolysis.

This study investigates the influence of prolonged electrolysis on the electrochemical performance and surface characteristics of NiFe-modified compressed graphite electrodes used in alkaline water electrolysis. The electrochemical experiment was conducted over a two-week period at a constant temperature of 60 °C. The electrodes were evaluated for changes in surface morphology and composition using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The results demonstrated stable electrochemical performance with minimal current variation. However, significant structural changes occurred, including the formation of new microstructures on the cathode and the emergence of KHCO3 (potassium bicarbonate) compound on both electrodes. Crystallographic analysis revealed an increase in crystallite size and tensile lattice strain on the cathode, while the anode exhibited compressive lattice strains and a reduction in crystallite size. These findings suggest that the observed changes were driven by electrochemical annealing processes, contributing to material redistribution and surface modifications during prolonged electrolysis. This study provides insight into optimizing NiFe-based catalysts for enhanced durability and efficiency in water splitting technologies.