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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]

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

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

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

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

This paper 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]

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

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

Lightweight strategy is essential for the development of transportation vehicles and aerospace industries. As a type of lightweight material, high-strength aluminum alloys are limited to service temperatures below 200 °C due to the rapid coarsening of strengthening nano-precipitates, which cannot satisfy the increasing demands of practical applications. High-temperature applications beyond 250 °C become the bottle-neck problem of Al alloys. In this paper, we review existing literature on the improvement of high-temperature performance of aluminum alloys by stabilizing nano-precipitates. On the basis of atomic-scale microstructure regulation, several design strategies, such as interface segregation, co-precipitation, core/shell structure, and interstitial ordering, have been proposed, resulting in the development of a number of heat-resistant Al alloys for use at 300–400 °C. Moreover, the fundamental theories of solid-state phase transformation, especially precipitation aging and coarsening, are correspondingly advanced on the frontiers of science. [ABSTRACT FROM AUTHOR]

The positive relationship between knowledge transfer and knowledge innovation is recognized by most scholars, while knowledge heterogeneity, as a knowledge situation of the enterprise organization, affects knowledge transfer within enterprise organizations. Therefore, as a state, knowledge transfer can be regarded as a result of knowledge heterogeneity, and it becomes the intermediary state between knowledge heterogeneity and knowledge innovation. The organizational structure of individuals within an enterprise organization may affect these three elements and their interrelationships. In this paper, data are collected by means of on-the-spot investigation and a network questionnaire for analysis. The results show that the microstructure state of the individual in the enterprise organization plays a moderating role for the first three elements. The lower that the micro-restriction of the individual is, the more favorable the knowledge heterogeneity is for the inverted U-shaped impact of knowledge transfer and knowledge innovation and the more favorable the occurrence of knowledge innovation. [ABSTRACT FROM AUTHOR]

The paper studies the influence of accelerated cooling after helical rolling on the structure and mechanical properties of X70 steel in different sections of the rod. Accelerated cooling is carried out in two modes: cooling and holding at a temperature of 530°C (mode I) and cooling to a temperature of 200°C without holding (mode II). It is found that conditions of cooling affect the fraction and morphology of the bainitic phase. This in turn determines different microhardness and strength in different sections of the rods. [ABSTRACT FROM AUTHOR]

The concentration of heavy metals in soil layers has increased due to the rapid development of the industry. Lead and zinc are two frequent heavy metal contaminants in soil. This paper aims to study the effect of these types of contaminants on different fines, including kaolinite, bentonite, and zeolite mixed with sand. First, mixtures of sand and kaolinite, bentonite, and zeolite were prepared, then they were contaminated by two contaminants of lead and zinc nitrates, separately. Consolidated undrained triaxial tests, Soil Conservation Service (SCS) double hydrometer tests, scanning electron microscope (SEM), Atterberg limits, and pH determination tests were conducted on the soil samples to investigate the changes in the strength and microstructure in the presence of heavy metals. In general, triaxial test results showed that various parameters influence the strength results of these heavy metal-contaminated sandy soil samples such as type, percentage, and structure of the fine portion, type, and concentration of contaminants, bonding mechanism of fine grains, and ion exchange capacity. For instance, in the presence of kaolinite (and kaolinite-zeolite mixtures), contamination with lead decreased the strength of soil samples, but in the soil mixtures containing bentonite (and bentonite-kaolinite mixtures), an opposite trend was seen. The plasticity index of mixtures containing kaolinite and zeolite increased in the presence of heavy metal contaminants, but it decreased when the fine portion of the soil was bentonite. Heavy metal contaminants decreased the pH of all soil mixtures and made them to be acidic. The results of the SCS double hydrometer test and SEM indicated that contaminated kaolinite and zeolite soil mixtures have a dispersed structure, while bentonite soil mixtures are not dispersive. [ABSTRACT FROM AUTHOR]

The mechanisms of microstructure transformation and mechanical anisotropy of laser-MIG hybrid additive manufacturing TC11 titanium alloy after solution aging treatment are investigated. In this paper, different solution temperatures and cooling modes are applied to tailor the microstructure and improve high-temperature properties and anisotropy. The result shows the microstructure of the samples in the as-deposited state is dominated by a widmanstatten structure composed of lamellar α clusters. Following solution aging treatment, a large area of basket-weave structure is obtained in the samples. A major influence of spheroidization of lamellar α clusters and dynamic recrystallization on mechanical anisotropy is revealed. The heat-treated samples exhibit more superior combined strength, elongation, impact toughness. The hardness difference between the layers and mechanical anisotropy decreases. During high-temperature tensile tests, the tensile strength increases with rising solution temperature; while, the elongation shows the opposite trend. The tensile fracture exhibits abundant uniform equiaxed dimples, and the fracture mode changes from intergranular fracture to transgranular fracture. Solution treatment at 990 °C for 2 h followed by air cooling is considered to be the optimal heat treatment process. Consequently, it results in a high tensile strength of 811 MPa and an excellent impact toughness of 50 J, representing improvements of 16.08% and 71.08%. [ABSTRACT FROM AUTHOR]

Plumology is being used in a variety of avian research fields such as from ecology and evolution to prey-predator relationship. However, very few systematic studies have been conducted in India using plumology. The paper compares macro- and micro-structural feathers' features from four species of family Columbidae viz. the Spotted dove (Spilopelia chinensis), Grey-fronted green pigeon (Treron affinis), Eurasian collared dove (Streptopelia decaocto) and Common pigeon (Columba livia) from different Indian localities. A morphometric analysis of the downy and contour feathers' structures of the listed species was carried out. Since the feathers were taken from significantly damaged carcasses, it was necessary to determine the pterylae of the flying feathers to which the latter belong. Morphometric features of feathers viz. calamus, rachis, vane and mounted barb length were measured. An atypical for Columbidae feature presence of villi has been observed but only for T. affinis species. The presence of typical pigmented quadrilobed nodes was noted in all Columbidae species. Pigmented and non-pigmented plain pronged nodes and plain swollen nodes were observed. The presence of three different nodes on barbules and nodes' pigmentation may be considered as key taxonomic characteristics for studied Columbidae species. The feather comparison method made it possible to identify pterylae of studied feathers. [ABSTRACT FROM AUTHOR]

Developing hollow components that integrate a large number of complex coolant channels for thermonuclear reactors remains a challenging task, owing to potential technical problems such as dissimilar metal connections, over-aging, and large welding areas (meter-scale). In this paper, CuCrZr/316L hollow components were manufactured using an improved explosive welding technique, where theoretical calculations and composite filling mold were used to achieve ideal welding conditions. Microstructure analysis showed that irregular waves of continuous and complete metallurgical bonding were detected at the bonding interface, and the defects at the corner of the flow channel were controlled at the hundred-micron level. The joint exhibited high shear strength (~ 292 MPa) under the given high-temperature conditions (200 ℃), whose peak strength, stress–distance curve, and failure mode were almost consistent with the experimental results at room temperature (25 ℃). Finally, under all conditions of the helium-leak test, the leak tightness of the CuCrZr/316L hollow component met the standard requirement. [ABSTRACT FROM AUTHOR]

This paper is a study of the mechanical properties and microstructures of the similar friction weld joints (TiAl6V4 and AA2024) using a servo-controlled Rotary Friction Welding (RFW) system. The friction welding operations were performed with seven different values of the friction pressure in the range of 2–14 MPa. The temperature is recorded during friction welding tests using k-type thermocouples. Tensile tests and microhardness measurements were carried out to obtain the mechanical properties of the friction weld joints. Microstructural changes of individual zone of the friction welds were investigated using an optical microscope (OM), and the fracture surfaces were observed using a scanning electron microscope (SEM). For AA2024, the fracture occurs most frequently in the central zone, resulting in lower tensile strength values, while for TiAl6V4, the fracture is occurs outside the friction weld interface, indicating that the friction weld joint is more resistant than the base metal. Microscopic analysis of the fracture surfaces of the AA2024 samples revealed diverse morphologies, with rough cupular surfaces predominating, indicating a dominant ductile fracture mode. Similarly, TiAl6V4's friction welded specimen also exhibited cupules of various sizes across its surface, primarily associated with a ductile fracture mode. Overall, the optimal friction pressure values (respectively 8 and 10 MPa for TiAl6V4 and AA2024) correspond to the highest values of the mechanical properties. [ABSTRACT FROM AUTHOR]

Tribaloy™ T800, a Co-based alloy, exhibits remarkable tribological properties by virtue of its high-volume fraction of intermetallic Laves phase making it an attractive hard-facing material. Hard-facing by laser deposition results in dilution from the substrate, and thereby, the properties of the clad are altered. This paper reports the influence of processing parameters on the dilution, microstructure, and wear behaviour of Tribaloy™ T800 on AISI 316 stainless steel. A systematic set of 20 clads was deposited by varying laser power and cladding speed, keeping powder flow and spot diameter constant. While dilution decreased at lower laser powers (800 and 1000 W) with increasing cladding speed (5–20 mm s−1), at higher laser powers (1200 and 1400 W), the opposite trend was observed. The Fe intermixing from the substrate along with the cooling rate governs the volume fraction and size of the Laves phases which controls the properties of T800 clads. The clad with the least geometric dilution (5.7%) exhibits the lowest wear rate of 0.54 × 10−5 mm3 N−1 m−1, increasing to 2.88 × 10−5 mm3 N−1 m−1 as the dilution increased to 60%. [ABSTRACT FROM AUTHOR]

In this paper, high-density (60−x)Fe−Cr−Co−xCu (x: 0–6 wt.%) permanent magnet alloys were fabricated by laser powder bed fusion (LPBF) in-situ alloying technique, and the effects of Cu content on the microstructure, magnetic, and mechanical properties of the alloy were systematically investigated. The addition of 2 wt.% Cu enhanced the coercivity H c and the energy product (B H) max of the alloy in the isotropic state by 19.4 and 27.9%, respectively, compared to the alloy without Cu. The impacts of Cu content on the magnetic properties were investigated by combining experimental results and first-principles calculations. Furthermore, the addition of Cu improved the yield strength of the alloy, and the strengthening mechanism was analyzed in detail. The yield strength of the alloy with 2 wt.% Cu reached 908 MPa, representing a notable 7% increase relative to the Cu-free alloy. [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]

Gear shafts are commonly manufactured by machining of gear teeth and shaft separately. This kind of approach entails quite some problems, such as long processing time, large die, and low production efficiency. To tackle these problems, this paper innovatively proposes a new process of cross wedge rolling (CWR) that is specifically tailored to the manufacturing of gear shafts, with which the shaft and teeth are formed at one go. The finite element model of CWR forming of gear shaft is established to simulate and analyze the CWR forming process. A three-factor and three-level response surface test is designed to optimize the processing parameters, where the friction coefficient, rolling temperature, and die movement speed are chosen as three factors, and inhomogeneous deformation is set as the response. The optimal parameters are obtained as follows: the rolling temperature is 1240 ℃, the speed of the die movement is 336 mm/s, and the friction coefficient is 0.8. This result is subsequently verified by experiments. Further on, the microstructure evolution of the characteristic points of the CWR forming process of gear shaft is analyzed. It is found that the grains at the gear teeth section are continuously refined and grown from the boundary at the early section of deformation, and the final grains grown are much smaller than the original ones. In addition, the grains appear to grow in a short range of time in the process of deformation, but the overall trend is towards refinement. In the shaft section, the evolutions of the grains in the two stepped shaft segments are almost the same; the grain deformation shows cyclic changes; the degree of grain refinement in the shaft is higher than that in the teeth; and the degree of grain refinement in the shaft center is higher than that in the shaft edge. The results of the study provide a theoretical basis for short-process forming of high-performance gear shafts by cross wedge rolling. [ABSTRACT FROM AUTHOR]

Laser-based powder bed fusion (LPBF) is a widely utilized technique for additive manufacturing (AM) of metal components. The size of LPBF-produced parts is restricted by machine dimensions. Welding emerges as a feasible solution for connecting smaller parts generated via PBF. Nevertheless, the weldability of PBF parts differs from conventional ones due to the unique thermal history of PBF components. This paper investigated the weldability of stainless steel 316L and tensile behavior of welded samples, comparing samples produced through LPBF and the conventional wrought method. Tensile testing, grain size analysis, microhardness test, and assessment of secondary dendrite arm spacing were conducted on every welded combination of materials (AM-AM, wrought-wrought, and AM-wrought) using gas tungsten arc welding (GTAW). The findings indicate that the wrought material demonstrates a higher maximum strength (577.5 MPa) and a lower yield strength (231.7 MPa) compared to the AM material (with a maximum strength of 548.2 MPa and a yield strength of 399.9 MPa). This difference may be attributed to the annealing process applied to the wrought material, which has not been applied on the AM material. Additionally, welded wrought samples have a significantly lower tensile strength compared to non-welded samples. The wrought samples exhibit a larger average grain size (11.14 to 31.12 μ m ) in the heat affected zone (HAZ) compared to non-heat affected regions (8.13 μ m ). In contrast, it is found that grain coarsening does not occur in PBF samples, which exhibit a similar grain size in the HAZ (15.04 μ m ) vs 13.97 μ m outside of the HAZ. Larger grain sizes within the HAZ correspond to a larger reduction in tensile strength for the wrought samples, compared to PBF samples. Similar secondary dendrite arm spacing has been observed in the weld regions of both PBF and wrought materials. Microhardness test results indicated that the AM base material has the highest microhardness and gradually decreases as transitioning to the HAZ and weld region. In summary, the PBF samples exhibit less reduction of strength and ductility after welding than wrought samples. Therefore, it is determined that additively manufactured 316L stainless steel has a higher weldability than traditionally manufactured wrought 316 stainless steel. [ABSTRACT FROM AUTHOR]

The direction in which wire and powder feedstock are fed influences deposit quality of as-built parts produced using laser-direct energy deposition (L-DED). While lateral wire feed has been explored in existing L-DED investigations, limitations like process instability persist, especially in achieving the required connection between the wire and the melt pool. Co-axial feedstock deposition offers a potential solution, enabling higher manufacturing flexibility and efficiency by co-axially feeding wire or powder. However, the full potential of L-DED using co-axial feeding for metal components remains underexplored due to equipment limitations. This study systematically evaluates the printability of stainless steel (SS) 316L and compares the microstructures and microhardness properties between co-axial powder-fed and wire-fed L-DED specimens. Utilizing the MELTIO M450 L-DED system in an argon environment, single-layer three-track specimens are produced with different combinations of process parameters. Comprehensive characterization, employing optical and scanning electron microscopy alongside microhardness testing, reveals powder-fed specimens exhibit greater melt pool depth and cooling rates, while wire-fed counterparts display fewer oxide inclusions and smoother surfaces. Microstructural differences include higher δ-ferrite content in wire-fed specimens. Microhardness values between powder-fed and wire-fed specimens are comparable. These findings hold implications for sequential powder and wire deposition, enabling the production of diverse mechanical structures with distinct characteristics. Overall, this paper provides an insight into feedstock selection for efficient metallic part production via co-axial feedstock deposition and recommends a range of process parameters suitable for fabricating SS316L parts using co-axial deposition in L-DED. [ABSTRACT FROM AUTHOR]

The thermal conductivity of soil is an essential parameter for designing geothermal energy foundations and borehole heat exchange systems. To effectively improve the development efficiency of geothermal resources in the loess region of China, the plane heat source method was used to measure the thermal conductivity of loess samples with different water contents and temperatures, and scanning electron microscopy tests were conducted. Analyze the effects of water content, temperature, and soil microstructure on thermal conductivity. A weighted geometric mean model considering the soil temperature effect is proposed and compared with the traditional model. The experimental results reveal that soil thermal conductivity increases in stages as the temperature rises. After the temperature exceeds 30℃, the contribution of steam latent heat transfer to soil thermal conductivity gradually becomes significant. Within the temperature range of 1–60℃, the thermal conductivity increases with increasing saturation and tends to stabilize after saturation exceeds 60%; When the temperature is greater than 60℃, the thermal conductivity peaks near a saturation of 60%. As the water content increases, there is a significant difference in the thermal conductivity of undisturbed and remolded loess, which is related to the microstructure changes of the soil. The model calculation shows that the weighted geometric mean model proposed in this paper has the best prediction performance. The Leong model has good predictive performance for the thermal conductivity of loess, while the Gori and Lusen models have the lowest predictive accuracy. [ABSTRACT FROM AUTHOR]

In this paper, the effect of deep cryogenic treatment (DCT) on the microstructure and properties of automotive 6063 aluminum alloy at different times was investigated with automotive 6063 aluminum alloy as the research object. The results show that under the conditions of deep cryogenic treatment, the lattice distortion occurs in the alloy matrix microstructure, and the resulting internal stress promotes the large proliferation of dislocations within the alloy and the increase of dislocation density; meanwhile, after the deep cryogenic treatment, the deformed grains are transformed into recrystallized and sub-crystals structural grains, the grains are refined, and the size of the grains is refined from the original 25.2 μm to 20.3 μm, with fine equiaxed crystals. Among them, the mechanical properties of the DCT36h specimen were the best, and its hardness, tensile strength, yield strength and elongation reached 142.44 HV, 328.32 MPa, 177.42 MPa, and 29.29%, which were 34.17%, 5.62%, 11.10%, and 32.77% higher than the original sample, respectively. We believe that the main mechanism for the increase in toughness is multiple reinforcement such as dislocation strengthening, grain refinement strengthening, precipitated phase strengthening and texture strengthening. [ABSTRACT FROM AUTHOR]

In this paper, preforms with three-dimensional structures and different thicknesses were constructed by 3D printing technology, and WC particle reinforced high-chromium cast iron (HCCI) composites was prepared by infiltration casting method. The microstructure of the WC/Fe matrix composites was investigated using scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The effects of different preform wall thickness on the hardness and three-body abrasive wear properties of the composites were tested. The results showed that with the increase in the wall thickness of the three-dimensional preform from 2.5 to 10 mm, the volume of the composite zone formed by the dissolution diffusion reaction of WC and HCCI gradually increased from 31.8 to 41.2%. The microstructure was composed of composite zone, matrix and WC particles partially dissolved. The hardness of the composite zone increased at first and then decreased, while the wear weight loss of the composite showed an opposite trend. Compared with the wall thickness of 2.5 mm, the minimum wear weight loss of the composite was 0.2821 g for a wall thickness of 7.5 mm, and the wear resistance was improved by 12.8%. The hardness and wear resistance of WC/Fe matrix composites at different wall thicknesses were mainly related to the diffusion of the preform and the formation of the composite zone. [ABSTRACT FROM AUTHOR]

This research paper examines the effect of different solution heat treatments parameters (temperature and time) on Al–3.39%Cu–2.26%Mg (wt%) alloy's microstructure, thermal, mechanical and corrosion properties. 5754 alloy and Al–Cu alloy are used to make Al–3.39%Cu–2.26%Mg (wt%) by gravity die casting. Solution heat treatment at different temperature and time (500 °C-10 min, 500 °C-4h, 530 °C-10 min and 530 °C-2h). As-cast Al–Cu–Mg alloy have α-phase and eutectic phase. After solution heat treatment and aging, precipitates phases is observed in microstructure. X-ray diffraction analysis results have shown that a precipitate phase [S phase (Al2CuMg)] gets formed in as-cast conditions but undergoes dissolution during the solution heat treatment process. As-cast Al–Cu–Mg alloy has a Brinell hardness value of 77.2 HB. As-cast alloy has S (Al2CuMg) precipitate phase increases hardness by precipitation strengthening. After solution heat treatment and aging, Brinell hardness reduces. After solution heat treatment (500 °C for 4 h) and aging (200 °C for 5 h), Brinell hardness values becomes 63.6 HB (− 17.6% decrease). Corrosion resistance improves after the solution heat treatment due to the dissolution of the precipitate phase, forming an almost single-phase solid solution. The as-cast alloy exhibits a peak compressive stress of 494.2 MPa, which increases after solution heat treatment and water quenching to 572.7 MPa (without aging). After aging, peak compressive stress decreases to 508.4 MPa. Failure strain for the as-cast alloy is 39.6%, reducing to 31.1% after solution heat treatment and water quenching. It again increases to 43.1% after aging. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of gas dynamic cold spraying followed by laser processing of stainless steel samples on their dynamic (spallation) strength under the impact load at a 105 s–1 strain rate. The impact velocity effect on the microstructure and dynamic strength is studied herein. It is shown that the dynamic strength of steel samples after laser processing remains unchanged compared to unprocessed samples. Amorphization and melting are observed in the spallation region of the processed samples. Intense mechanical twinning develops inside austenite grains after the load application, and a largest number of twins is observed in unprocessed samples. [ABSTRACT FROM AUTHOR]

AlCoCrFeNi2.1 eutectic high-entropy alloys (HEAs) are a new kind of alloy with high entropy and eutectic properties. Their advantages in terms of strength and shape matching can be fully exploited using extreme high-speed laser cladding (EHLA). In this paper, AlCoCrFeNi2.1 eutectic HEA coatings were prepared by conventional laser cladding (CLA) and EHLA. The microstructures and phase compositions of the two coatings were analyzed by scanning electron microscopy, x-ray diffraction, and electron backscatter diffraction. The microhardness and wear resistance values of the coatings were tested using a microhardness tester and a friction and wear tester, respectively. The results showed that the surface qualities of both the CLA and EHLA coatings were good and had no cracks or defects. Compared with those of the CLA coating, the EHLA coating had finer grains and a more uniform distribution. Both coatings contained face-centered cubic (FCC) and body-centered cubic (BCC) phases, but the BCC phase of the EHLA coating was less precipitated than the CLA coating. The higher microhardness and better wear resistance of the EHLA coatings occurred in the presence of Hall–Petch strengthening. [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]

To reveal the influence mechanism of linear heat input (LHI) on the mechanical properties and corrosion behaviors of SUS304 weldments manufactured by local dry underwater pulsed metal inert-gas welding (LDU-PMIG), phase structure, grain structure, grain preferred orientation, and grain type of weld metal (WM) were investigated in this paper. With LHI increasing, ferrite phase morphology transformed from lath to skeleton, and grain size was enlarged. The content of equiaxed grains was increased, and that of columnar grains was reduced remarkably. The mechanical performance ascended first and then reduced with the increase of LHI. The increase of equiaxed grain content and the diversification of grain preferred orientation were beneficial to the improvement of mechanical performance, then, grain coarsening led to mechanical performance decreasing. Besides, the corrosion potential, corrosion current and pitting potential of WM were detected through electrochemical corrosion tests. The results illustrated that the corrosion resistance of WM was lower than that of base metal (BM), and the corrosion rate was enlarged with LHI enhancing, which meant the corrosion resistance declining. The corrosion resistance was mainly determined by Cr precipitates, ferrite phase and grain size. The microhardness, tensile strength, and elongation reached their maxima in the LHI of 336.7 J/mm. The greatest corrosion resistance of WM was obtained in the LHI of 256.2 J/mm and reached 69.9% of BM. This study is meaningful to promote the further development and application of LDU-PMIG in marine underwater welding field. [ABSTRACT FROM AUTHOR]

Ni-based wrought superalloys are a type of superalloy produced through casting-forging processes, and usually their high-temperature performance is strongly influenced by microstructure and deformation mechanism. The typical microstructure of Ni-based wrought superalloys after heat treatments comprises equiaxed grains, numerous annealed twins, carbides within the grain interior and/or at grain boundaries, and spherical γ′ precipitates (typically comprises around 20% of their volume). The common deformation mechanisms in Ni-based wrought superalloys mainly include anti-phase boundary formed by paired dislocations shearing γ′ phase, stacking fault formed by single dislocation shearing γ′ phase, dislocation bypassing γ′ phase (precipitation-strengthened) and dislocation entanglement, dislocation networks (solid solution strengthened). In this paper, the microstructure and deformation mechanism of tensile and creep in Ni-based wrought superalloys for Advanced ultra-supercritical (A-USC) power plants are reviewed, for the two prominent areas of current research, Ni–Fe-based wrought superalloys exhibit superior processability and cost-effectiveness compared to Ni–Co-based wrought superalloys, thereby offering a more advantageous solution. [ABSTRACT FROM AUTHOR]

Steel matrix composites are widely used in automotive, aerospace, wear, and cutting applications due to their superior mechanical properties, ease of manufacture, and low cost. However, there are still some limitations in the strength, reinforcement dispersion, and interface control of steel matrix composites, which are mainly achieved through different preparation processes and the addition of reinforced particles with mixed metal powders. Previous studies have demonstrated the enhanced ability of various reinforcing particles such as titanium carbide, silicon carbide, and alumina to enhance the wear performance of steel substrates, but there are still some challenges, such as uneven particle distribution, interface cracks, and unsatisfactory wettability. In this paper, the preparation methods of ceramic-reinforced metal matrix, ceramic reinforcement, steel matrix composition, microstructure, mechanical properties, and wear properties, as well as the parameters affecting their properties, are reviewed. The preparation processes of different ceramic-reinforced steel matrix composites are introduced, which are very suitable for overcoming challenges such as insufficient strength, poor dispersion, uneven distribution, and poor interfacial wettability. The influence of the morphology distribution and volume fraction of reinforcement on the wear rate of steel matrix composites was discussed. The importance of the microstructure of ceramic reinforcement in steel matrix and the interface between ceramic and matrix to improve the mechanical properties of steel matrix composites were emphasized. This review identifies the development trends in the field of research to fully illustrate the importance of more in-depth scientific research in steel matrix composites. [ABSTRACT FROM AUTHOR]

In this paper, in-plane vibration characteristics of square metamaterial plates, which are made of three-dimensional periodic arrangement of the coated spherical particles embedded in a matrix, are investigated theoretically. First, the effective material properties of the plates, including elastic constants and mass density, are obtained by using a simple homogenization method. Then, the governing equations of in-plane vibration are derived and solved analytically for simply supported boundary conditions. In addition, to verify the proposed formulations, the resonance frequencies and corresponding mode shapes of the plates are calculated via commercial finite element method software. Then, a parametric study is performed to illustrate the effects of the geometrical and material properties of the unit cells on the frequencies of metamaterial plates. [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]

With the rapid development of industrial manufacturing, traditional WC–Co cemented carbides have exposed more and more problems. Therefore, the preparation of ultrafine/nanocrystalline-grained cemented carbides and the development of new binders have become a hot issue in the field of cemented carbides. Due to the unique design concept, the high-entropy alloys (HEA) binder not only has the unique properties of the HEA itself, but also can replace the traditional Co element as the binder of cemented carbide, which opens up the possibility for industrial manufacturing. The stable chemical properties of WC are coupled with the multi-principal element characteristics of HEA binder, which makes novel WC-HEA cemented carbides have the characteristics of grain refinement, compact structure, stable structure, and excellent capability. A multitude of studies have found that the new WC-HEA cemented carbide exhibits better service performance than WC–Co cemented carbide. In this paper, the main preparation processes of WC-HEA cemented carbide in recent years are summarized; the influence of the working principle, advantages, and defects of the two different preparation methods on the microstructure and properties of WC-HEA cemented carbide were described. The characteristics and influence mechanism of microstructure such as the composition of high-entropy alloy binder and the change behavior of phase structure of WC-HEA cemented carbide were discussed. The service performance characteristics of WC-HEA cemented carbides were discussed, including mechanical properties, wear resistance, oxidation resistance, and corrosion resistance. Finally, it summarizes the research challenges and prospects in the current research work, and provides an outlook on the research direction and application prospects of WC-HEA cemented carbide. [ABSTRACT FROM AUTHOR]

In this paper, the Al–K2ZrF6–KBF4 reaction system, a melt reaction method, was used to prepare in situ ZrB2/AA6111 particle-reinforced aluminum matrix composite. The modification of friction stir processing (FSP) and T6 heat treatment (HT) was carried out for this composite for the first time. The reinforcing particles in the stirring zone after FSP+HT were refined from 1.7–1.9 to 0.1–0.3 μm. The grain size was refined from 10–50 to 2–5 μm and then slightly coarsened to 3–10 μm. The tensile strength of the FSP stirring zone is 193.40 MPa, the elongation is 29.33%, and the average hardness is 60 HV. The hardness of the stirring zone is not uniform and fluctuates in a large range of 53–80 HV. After the T6 heat treatment, the tensile strength of the stirring zone increased by 63.8% to 316.75 MPa. The tensile strength was 13% higher than that of T6-6061. The elongation remained at 30.12% and did not decrease. The elongation is 10% higher than that of other 6xxx aluminum alloys and composites after T6 heat treatment. The plasticity-reduction of the conventional alloy after T6 heat treatment was solved. The property is more uniform and the average hardness is 120 HV. Calculated by the theoretical model, the yield strengths of the stirring zone of the original composite, FSP, and FSP+HT composites were more than 96% consistent with the experimental values. [ABSTRACT FROM AUTHOR]

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

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

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

The microstructure of the porous anode plays a crucial role in the mass transfer dynamics and electrochemical reaction of solid oxide fuel cells (SOFCs), significantly impacting their performance. This paper investigates the effect of microstructure of the porous anode on mass transfer and electrochemical reaction in SOFCs, which addresses the scarcity of research due to the complexity of microstructure modeling, offering supportive information for the structure optimization of SOFCs. Firstly, theoretical deductions of constructing microstructure and simulating mass transfer are conducted. Subsequently, a construction model is established based on the fractional Brownian motion (FBM) model to obtain different microstructures, encompassing various flow pore structures, triple phase boundary (TPB) structures, and inlet structures. Through a finite difference lattice Boltzmann method (LBM), the mass transfer is modeled to predict gas molar fraction distributions and calculate concentration overpotentials with different microstructures. Finally, thorough experiments are carried out to analyze the effect of structural parameters on mass transfer and electrochemical reaction. Taking the hydrogen-steam-nitrogen (H2-H2O-N2) ternary mass transfer as an example, the comparison results indicate that complex flow pore structures increase both the distance and resistance of mass transfer. To improve the performance of SOFCs, reducing flow pore complexity and increasing TPB length both mitigate the effect of concentration polarization. Moreover, the change of inlet structure suggests minimal impact on mass transfer and electrochemical reaction. [ABSTRACT FROM AUTHOR]

The paper comparatively investigates the microstructure, mechanical, and damping properties of hypoeutectic Al–Si–Cu casting alloys prepared by the cooling slope casting and thixoforming process. Microstructural analysis shows that cooling slope process refined the grains and promoted the transformation of equiaxed dendritic α-Al to rosette morphology. Subsequent thixoforming further enhanced this refinement, generating a microstructure of α-Al globules and spheroidized eutectic silicon particles. These microstructural alterations significantly improved their mechanical properties. Notably, the thixoformed samples exhibited a remarkable increase in yield strength from 139 to 193 MPa (38%), ultimate tensile strength from 145 to 205 MPa (42%), and fracture elongation from 1.1 to 3.2%. The damping analysis revealed a significant increase in both the loss modulus and damping capacity, while the storage modulus decreased at high temperatures for all samples. Consequently, the thixoformed samples displayed a distinct improvement in both their mechanical characteristics and damping capability. [ABSTRACT FROM AUTHOR]

In this paper the influence introducing various plasticizers into an initial charge on the structure and properties of iron-based powder materials alloyed with copper is considered. It is shown that introduction of copper stearate into an initial powder mixture and warm mixing, pressing and subsequent sintering makes it possible to obtain low-porosity workpieces with relative porosity of 95%. Pores within the workpieces obtained have a small size of 10–15 microns and a rounded shape. Also, bending strength is determined for sintered samples of all the compositions of powder mixtures studied and the Rockwell hardness is determined on the C scale. Powder steels based upon mixtures have the best set of mechanical propertiesPZhRV 2.200.28 + 0.7 wt.% Br + 0.7 wt.% Cu + 1 wt. % StCu + warm mixing—hardness HRC 58. flexural strength 600 MPaPZhRV 2.200.28 + 1.4 wt.% Br + 1.4 wt.% Cu + 1.4 wt.% C + 1.0 wt.% StFe + warm mixing—hardness HRC 100, flexural strength 530 MPaPZhRV 2.200.28 + 0.7 wt.% Br + 0.7 wt.% Cu + 1 wt. % StCu + warm mixing—hardness HRC 58. flexural strength 600 MPaPZhRV 2.200.28 + 1.4 wt.% Br + 1.4 wt.% Cu + 1.4 wt.% C + 1.0 wt.% StFe + warm mixing—hardness HRC 100, flexural strength 530 MPa [ABSTRACT FROM AUTHOR]

In this paper, x wt.% Mg2Si/Al–5 wt.% Cu (x = 5, 10, 15, 20, and 25) composites were prepared by an in situ process. The effect of phase content of Mg2Si on their microstructures and performances was investigated; the dry sliding wear behavior under room temperature was examined. The results show that with the increase in Mg2Si (Mg and Si) concentration, the microstructure of the Al–Mg2Si composite changes significantly. The eutectic microstructure changes from lamellar labyrinth to long rod, along with the long-range order Al2Cu phase to island and plate-like morphology, and the primary Mg2Si phase becomes more compact. The hardness increases from 117 HV to 163 HV. The friction coefficient, wear rate, wear width, and wear depth decrease from 0.368 ± 0.048, 2.7 × 10−5 mm3/m, 1.93 mm, and 133.3 μm to 0.315 ± 0.016, 1 × 10−5 mm3/m, 0.94 mm, and 70.2 μm, respectively. The tested composites worn surfaces exhibit adhesion, peeling, microcutting wear, abrasive, and oxidation. [ABSTRACT FROM AUTHOR]

Cu–Al–Fe shape memory alloys are a new kind of smart materials with high phase transition temperature. However, poor thermal stability and poor shape memory effect limit the commercial application range. In this paper, the effect of Al content on microstructure, thermal stability, shape memory effect and mechanical properties of Cu–Al–Fe shape memory alloys was investigated systematically by changing Al content, so as to obtain the optimal composition ratio for better commercial application. The results show that in the as-cast state, the microstructure is a mixture of (Cu) phase, β′ martensite and Fe(Cu, Al) phase with Al content of 11 mass%, and a mixture of β′ martensite and Fe(Cu, Al) phase with Al content of 12 mass% and 13 mass%. After quenching, β′ martensite exists in all alloys, while (Cu) phase and Fe(Cu, Al) phase disappear, and γ′ martensite also exists at Al content of 13 mass%. The shape memory alloy effect of as-cast alloy is enhanced with the increase of Al content, while the shape memory effect of quenched alloy increases first and then decreases. Among them, Cu82Al13Fe5 has the best shape memory effect, the recovery ratio reaches 84.38%, and it also has the best thermal stability. [ABSTRACT FROM AUTHOR]

This paper is dedicated to studying the effect of replacing molybdenum with vanadium on the tendency to amorphisation, structure, and thermal properties of high-entropy alloys of the (Fe0.25Ni0.25Co0.25Cr0.125Mo0.125‑xVx)100‑yBy system, where x = 0; 0.0625; 0.125 and y = 17–25. The alloy structure was analyzed using X‑ray diffraction, scanning and transmission electron microscopy methods. Thermal properties were determined by differential scanning calorimetry. It was found that the replacement of molybdenum with vanadium leads to the formation of crystalline particles of complex nitrides (V, Cr, Mo)(N, B) in the ribbon structure. The dependences of the characteristic alloy temperatures have been established. Molybdenum replacement with vanadium was shown to stabilize the supercooled liquid in alloys with completely amorphous structure. [ABSTRACT FROM AUTHOR]

Vortex-free high-speed stir casting (VFHSC) methodology can achieve uniform dispersion of particles in melt without air entrapment for fabricating particle reinforced composites, and it has been proved to be feasible for preparing micron-composites by this methodology. In this work, in order to study deeply on particles in nano-size magnitude in composites by this methodology, the preparation of 1.5 vol.% Nano-Al2O3p/Al–Cu–Mg–Si composite is also investigated. The proper stirring parameters for ideal particle dispersion are determined to prepare the materials. Porosity of the composite can be limited to 0.147 % under the VFHSC methodology. The composition and microstructure of ingots, including the incorporation of Al2O3 particles as well as the morphology of precipitated phases, are examined by OM, XRD, SEM, TEM, HRTEM and EDS. The nano-particles are incorporated ideally in the matrix with restricted aggregation and sedimentation, and the well-bounded Al2O3–Al interface possesses semi-coherent interface. Moreover, the VFHSC 1.5 vol.% Nano-Al2O3p/Al–Cu–Mg–Si composite exhibits obvious strengthening, limited ductility reduction, higher hardness as well as better wear resistance than those of matrix, validating the efficacy of the VFHSC methodology on fabricating 1.5 vol.% Nano-Al2O3p/Al–Cu–Mg–Si composite. The work proves that incorporating nano-particles in Al matrix by VFHSC methodology is feasible and efficient. The work presented in this paper proposes a viable approach for the fabrication of nanocomposites using the stir casting method, thereby offering valuable insights for further research on stir casting technology. [ABSTRACT FROM AUTHOR]

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

The preparation of coordination polymers with good room temperature phosphorescence is the focus of current research. In this paper, zinc and cadmium were used as metal ions and 2,3-pyridinedicarboxylic acid (H2L = 2,3-pyridinedicarboxylic acid) was used as organic ligands to successfully synthesize Cd (II) homometallic [CdL]·H2O and Zn(II)Cd(II) heterometallic [ZnCdL2]·DMF·5H2O coordination polymers microstructures. In addition, morphology, powder X-ray diffraction (PXRD), infrared spectroscopy (IR), elemental analyses, thermogravimetric analysis (TGA) and their luminescence properties were studied. Cd-CP is a micron-sized spherical structure, while Zn/Cd-CP is a flower-like structure formed by the accumulation of sheets. The results show that Cd(II) homo- and Zn(II)Cd(II) heterometallic coordination polymers have quantum yields of 10.05% and 8.54%, respectively. It is worth noting that the lifetime of Cd-CP is 124.62 ms, while the lifetime of Zn/Cd-CP is significantly extended to 363.09 ms after doping with metal ion Zn2+. The phosphorescent lifetime of coordination polymers was improved by the heterometallic doping strategy, which provided a new idea and method for the preparation of coordination polymers with long-lived room temperature phosphorescent properties. In addition, the two coordination polymers exhibited blue and cyan fluorescence at 365 nm UV light, respectively, and a green afterglow of about 2 s could be observed with the naked eye when the UV lamp was turned off. [ABSTRACT FROM AUTHOR]

The semi-solid slurry preparation process, microstructure, and mechanical properties of truck coarse filter bracket were studied in this paper. The semi-solid aluminum alloy slurry with high solid fraction was prepared by the Slurry Enthalpy Equilibrium Device (SEED) method, and the optimum slurry preparation parameters were determined through the observation and analysis of the slurry microstructure as follows: pouring temperature 700 °C, rotation speed 180 r/min, and crucible temperature 400 °C. The average grain size and shape factor of the slurry prepared under these conditions are 50.448 μm and 0.799. Die casting trial production which used the best process parameters of slurry preparation and die casting was carried out. The results show that the die casting parts are completely filled with no obvious surface defects. It can be seen from the cutting experiment and X-ray non-destructive test that the internal structure is dense and uniform, and there are no obvious casting defects that were observed such as cracks and holes. The semi-solid die castings were strengthened by T6 heat treatment. The experimental results showed that the optimal heat treatment parameters were a solution temperature of 470 °C and time of 4 h, aging temperature of 175 °C and time of 12 h. Under these conditions, the microstructure morphology was improved significantly. The tensile strength and yield strength reached 342.1 MPa and 309.1 MPa, respectively, which were 38.9% and 95.3% higher than the semi-solid state, and the elongation was 4.5%. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Si content on the microstructure and mechanical properties of the Al–1.2Mg–xSi–1.2Cu–0.6Mn cast alloy was investigated. The study aimed to explore the optimal addition of Si element to improve the comprehensive properties of alloys. The microstructure, phase composition and fracture morphology of the alloy were determined through OM, SEM, EBSD and XRD analysis. The Si content in the alloy ranged from 0.48 to 2.4 wt.%. With the increase of Si content, the number of strengthening phases increases, which improves the comprehensive properties of the alloy. When the Si content is 0.8 wt.%, the eutectic Mg2Si transforms from rod-shaped to larger block shaped, and the formation of coarse Mg2Si phase limits the elongation of the alloy. When the Si content is 2.4 wt.%, fine Al2Cu phases are present in this alloy and coexist with Al(Fe,Mn)Si phases, while an increase in the Si content appears as partially accompanied by an incipient crystalline Si phase around the Al(Fe,Mn)Si phase. The alloy exhibits a maximum tensile strength, yield strength and elongation of 198.2 MPa, 101.2 MPa and 4.96%, respectively, with a hardness of 80.94 Hv. It consists of five alloy phases, mainly α-Al, Mg2Si, Al(Fe, Mn)Si eutectic phase, Q-AlCuMgSi eutectic phase and the beginning crystalline silicon phase formed due to the increased Si content. The Si content can improve alloy strength, but there is some damage to the toughness of the alloy. Higher silicon alloy content results in the formation of fine Al2Cu eutectic. This result makes it possible to achieve a higher level of strength with a reduced loss of ductility in the alloy. [ABSTRACT FROM AUTHOR]