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In this study, the effect of welding currents and welding times on the microstructure and mechanical properties of the dissimilar welded joints of Q&P980 and Q&P1180 steel was investigated. The macrostructure and microstructure of the dissimilar welded joints were characterized and the relationship between the welding parameters and the mechanical performance was analyzed using confocal laser scanning microscope, scanning electron microscope, and mechanical properties testers. Results show that with the increasing welding current and welding time, the nugget diameter, indentation rate, and maximum shear force of the dissimilar joint increase. The absorption energy of the dissimilar joint increases when the welding current rises, while it increases first and then decreases with elevating welding time. All the hardness distributions of the dissimilar Q&P980/Q&P1180 joints exhibit the highest hardness value in the fusion zone and a gradually decreasing hardness value in the heat-affected zone. Moreover, with increasing current and time, much higher hardness occurs at the FZ/HAZ boundary. The microstructure characterization illustrates the martensite fraction in the intercritical heat-affected zone of the Q&P1180 side is higher than that of the Q&P980 side after the welding process. With the increase of welding current and time, the lath martensite in the fusion zone gradually coarsens. The coarsening martensite and the nugget diameter are responsible for the change in the shear force and energy absorption of the dissimilar Q&P980/Q&P1180 joints.

The class of NbC-Ni cermets has emerged as a promising environmentally friendly alternative to WC-Co cemented carbide tools, although some inherent properties i.e. room temperature hardness and flexural strength, of NbC-Ni cermets may require further enhancements. To enhance the properties of NbC-Ni cermets, diverse methodologies were applied, including grain inhibition and the strengthening of the cermet through the use of reinforcements. This study systematically examined the impact of TiC additions, specifically at 10% and 20%, on both the microstructure and mechanical properties of NbC-12Ni-4VC-4Mo _2 C cermets. NbC-12Ni cermets were fabricated via vacuum liquid phase sintering (LPS) at 1400 °C and 1450 °C. Enhancements by incorporating 4% VC and 4% Mo _2 C, followed by TiC at 10% and 20% concentrations to the NbC-Ni-4VC4Mo _2 C cermet were made. XRD and SEM results confirm the formation of (Nb, X, Y) C solid solution cubic FCC carbides. Significant grain refinement was evident in the cermet samples, subjected to grain inhibition. The observed grain sizes ranged from a maximum of 6.84 μm (in NbC12Ni) to a minimum of 2.154 μm (in the sample containing 20% TiC) at 1450 °C. The incorporation of 20TiC at 1450 °C led to a remarkable 26.5% enhancement in average hardness compared to NbC-Ni cermet, and a 4.2% improvement over the 4VC4Mo _2 C cermet. At 1450 °C, 20TiC reinforcement led to an average fracture toughness of 9.331 MPa√m, representing a 4.56% improvement over the 4VC4Mo _2 C cermet. However, there was a marginal reduction in toughness compared to the NbC-Ni cermet. Moreover, the addition of TiC led to a decrease in the flexural strength of the cermets, with a maximum flexural strength of 939 N mm ^−2 recorded for NbC-Ni-4VC4Mo _2 C, representing an 11.6% increase compared to the NbC-Ni cermet.

The influence factors of small punch test (SPT) were investigated to evaluate the mechanical properties of gradient nanostructured (GNS) materials. The gradient nanostructure was prepared on the top layer of S30408 austenitic stainless steel by ultrasonic impact treatment (UIT). The mechanical properties of the GNS material were obtained using SPT and correlated with those obtained by standard tensile tests. The results indicate that, when the specimen thickness is 0.5 mm, the sphere diameter is 2.4 mm, the punch velocity is 0.5 mm min ^−1 , and the gradient nano-grained layer is placed face-on in the mold, the GNS material exhibits better plastic deformability. The SPT specimen achieves better bearing capacity, and the mechanical properties of the GNS material obtained by SPT are more accurate. The yield strength and tensile strength of the GNS material were also evaluated by analytical and empirical methods in SPT. The error is approximately 10% compared with the standard tensile test results, which is within the allowable range.

Green materials are currently demanded for construction as well as other products since the 26th UN Climate Change Conference of the Parties (COP26) in 2021. Using renewable and sustainable resources to innovate new materials such as composites is encouraged. This study aimed to investigate the physical and mechanical characteristics of wood plastic composites (WPCs) when adding waste tire rubber as filler for 10% or 20% by weight. The results showed that the density of the WPC samples (50 wt% wood − 50 wt% high density polyethylene) increased with the addition of the waste tire rubber (WTR) while the dimensional stability of samples was reduced. The mechanical properties of the WPC samples were determined, including flexural strength, flexural modulus, elongation at break, tensile strength, tensile modulus, and impact strength. The WTR as filler in the WPC tended to decrease the tensile strength and flexural strength whereas it improved the impact strength of materials. The results indicated that the WTR as recycled material in WPC affected the physical and mechanical properties of the WPCs. Although the use of the WTR in the production of the WPC adversely affects the mechanical properties, the use of 10 wt% WTR was acceptable. The results of the study showed that the addition of the WTR to the WPC production process can be useful for its recycling and for reducing the cost of the WPC.

Hybrid composite comprised fibers like peepal and Indian almond was fabricated, with the addition of natural filler such as jujube fruit seed particles aimed at enhancing composite performance. The impact of jujube fruit seed particles and layering sequence on the mechanical properties, water absorption and bio-degradation of the composites was investigated. Initially, two composite types, IA/P/IA (Indian almond/Peepal/Indian almond) and P/IA/P (Peepal/Indian almond/Peepal), were produced using hand layup practice, altering layering sequence of fibers. Based on tensile test results, the P/IA/P composite emerged as the optimal choice due to the denser packing of high-strength peepal fiber. Subsequently, jujube fruit seed particles were incorporated into the P/IA/P composite at varying weight percentages ranging from 2.5 to 10 with a step size of 2.5. The effect of jujube fruit seed particles on the performance of the P/IA/P composite was examined. The P/IA/P/7.5 wt% jujube composite demonstrated superior tensile, flexural, impact, and hardness properties, recording values of 82 MPa, 98 MPa, 5.2 kJ m ^−2 , and 86 shore-d, respectively. These values were 15.4%, 22.5%, 20.9%, and 4.8% higher than those of the P/IA/P composite. The P/IA/P/10 wt% jujube composite demonstrated minimal water absorption, with only 8% recorded over a 12-day period, as well as limited mass loss, totaling 27% over 60 days. Consequently, this research suggests that the P/IA/P/7.5 wt% composite holds promise for industrial applications.

The effect of different process parameters on Tungsten Inert Gas (TIG) welded dissimilar aluminium magnesium alloy AA5083-H111 and AA5052-H32 by using ER5356 filler rod and scandium added ER5356 composites is investigated in this research. Extremely required in the automobile and aerospace industries, some defects like micro pores and weaken the fusion zone on the joint are identified with ER5356 filler rod. To resolve these defects, scandium added ER5356 composite filler rod is used to compose the TIG welded joints with free defects. There are three different TIG welding process parameters like Current (A), gas flow rate (L/min) and (0, 0.25 and 0.5 wt% of Scandium with ER5356 filler rod are used by Taguchi L9 method. The macrostructure, microstructure and mechanical properties of TIG welded joints are investigated on all the welded samples. To optimize the process parameter is more significant, therefore grey relational analysis used to optimize the parameters with identified mechanical properties tensile strength and micro hardness, respectively. Out of different process parameters, joint made with process parameter current at 190 A, gas flow rate 10 l min ^−1 and 0.50% scandium added ER5356 enhances the mechanical properties (264 MPa and 119 Hv) which is maximum than other scandium free ER5356 and 0.255 scandium filler rod and enhanced strength welded sample exhibited fine grain refinement on the weld seam. Due to added scandium on the welded zones, secondary phase particles are generated during SEM examination and the optimized samples were utilized for fractography test to exhibit the ductile nature in fractured area. The EDS mapping also shows the elemental distribution on the welded zones, the scandium plays the major role as a better reinforcement to improve intermetallic strength. Finally, the grey with ANOVA also proves that the scandium added joints achieves influencing process parameters.

To accurately replicate actual production and save production costs, this study examines the influence of the tempering process on the structure, mechanical properties, and corrosion resistance of E690 marine steel. Various techniques were employed to evaluate its properties, behavior, and performance, including metallurgical microscopy, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, impact experiments, tensile tests, and electrochemical corrosion tests. The results indicate that as the tempering temperature increases, the tempering degree of the tempered martensite structure improves, the martensite strip coarsens, the size of the precipitated carbide increases, and the proportion of large-angle grain boundaries decreases. Consequently, the tensile strength and yield strength initially increase and then decrease, while the impact toughness and elongation gradually improve. At a tempering temperature of 600 °C, the steel exhibits the best overall mechanical properties, with a tensile strength of 729 MPa, yield strength of 649 MPa, and elongation of 18%. Furthermore, at a tempering temperature of 550 °C, the test steel shows an optimal corrosion resistance, with a corrosion rate of 0.03233 mm y ^−1 and an open-circuit potential of −0.36 V.

In this research, the electro-gas welding process was compared with a shielded metal arc welding process for welding steel A573 from a mechanical properties point of view. Visual and radiographic inspections confirmed the soundness of weldments produced by electro-gas welding and shielded metal arc welding techniques. Various assessments were performed, including hardness, tensile strength, V-notch impact toughness, macrostructure, microstructure, and electrochemical tests. The mechanical properties of the two welding processes were closely matched, with an average tensile strength of 590 MPa for electro-gas welding and 585 MPa for shielded metal arc welding. Furthermore, the influence of welding variables, such as groove design and heat input, on the welded joints’ quality, mechanical properties, and electrochemical behavior was thoroughly examined. Dilution estimates, particularly for the electro-gas welding process, were around 35%, and a significant similarity was observed between the chemical composition determined through dilution calculations and that obtained from chemical analysis using an arc spark emission spectrometer. Notably, the electro-gas welding process demonstrated exceptional productivity, surpassing the shielded metal arc welding process by more than elevenfold. The optimum welding parameters for the electro-gas welding process were identified to achieve superior mechanical properties, low corrosion rates, and reduced consumption of the welding electrodes. This included adopting a single V type and groove angle of 30° instead of 60°, resulting in a 23% reduction in economic costs. Selecting an appropriate heat input within the range of 12 to 14 kJ/mm further contributed to enhancing overall welding efficiency.

Wood-plastic composites are relatively novel composite materials that consist of a blend of wood flour waste with high-density polyethylene and polypropylene plastic waste, designed for use in ceiling applications. Various samples were produced using different ratios from the total weight, including 20:80, 30:70, and 40:60, with sieve sizes of 0.425 mm, 1.18 mm, and 2 mm. The composites were created by melting plastics and sawdust at a temperature of 180 ^0 c utilizing the hot-press moldings technique employing diverse formulations. The properties of sample composites were analyzed experimentally based on ASTM standards to investigate water absorption levels as well as flexural strength, impact resistance hardness along with surface morphology via the design of experiments. This research study indicates that nine composite formulations consisting of HDPE and PP plastics combined with wood flour can produce favorable physio-mechanical properties. Among these various combination specimens tested in this study FS3/FC30N exhibited excellent physio-mechanical properties; including desirable values such as water absorption level at 5.5103%, flexural strength at 61.12 Mpa, impact resistance measuring 33.45 J cm ^−2 , and hardness rating up to 80 RHB. Thus it is highly recommended for use in chipboard ceiling panel applications due to its potential benefits.

Wire-feed laser metal deposition (LMD-W) offers a high deposition rate and low cost, making it an effective solution for reducing costs and enhancing efficiency in manufacturing large-scale titanium aerospace components. Currently, the material used for LMD-W is typically a single alloy wire, which limits the flexibility and functionality of manufacturing composite materials. This work employed a novel concurrent wire-powder feeding laser metal deposition (LMD-WP) process to manufacture TiC/Ti-6Al-4V composite. In the LMD-WP method, Ti-6Al-4V wire was fed laterally, while TiC particles were delivered coaxially. Only 1.0 wt% TiC particles were added to prevent excessive TiC, which could cause stress concentration and increase crack sensitivity. The microstructure and mechanical properties of Ti-6Al-4V alloy and TiC/Ti-6Al-4V composite were investigated. The results indicate that with coaxial TiC particle addition, the α -Ti in TiC/Ti-6Al-4V is noticeably refined. Additionally, in situ TiC acts as heterogeneous nucleation sites, restricting α -Ti growth and reducing its aspect ratio. Furthermore, TiC particles weakened the α -Ti texture in the (0001) and (11–20) directions. Moreover, adding TiC particles significantly enhanced tensile strength, with the yield strength reaching 950 MPa and the ultimate tensile strength reaching 1048 MPa. Compared to Ti-6Al-4V alloy fabricated by LMD-W, this represents an increase of 11.25% and 10.72%, respectively. The improvement in tensile properties is principally ascribed to grain boundary strengthening, Orowan strengthening and dislocation density strengthening. This work introduces an innovative approach and abundant data for the additive manufacturing of TiC/Ti-6Al-4V composite with high efficiency and low cost.

This study evaluates the impact of incorporating varying contents (10–40 wt%) and molar concentrations (0.001–1 M) of citric acid solutions, as transient liquid phases in the Cold Sintering Assisted Sintering (CSAS) process of dysprosium zirconate (Dy _2 Zr _2 O _7 ). CSAS processed samples achieved relative densities up to 98% of the theoretical maximum and significantly increased Vickers microhardness by over 2.5 times, compared to the traditional ‘press and fired’ sintering method. The Dy _2 Zr _2 O _7 crystal structure remained consistent with the fluorite-type, with no secondary phases detected. Our findings underscore the benefits of using CSAS to enhance the mechanical strength of Dy _2 Zr _2 O _7 , while reducing the lengthy processing times at very high temperatures typically required for sintering refractory materials such as lanthanide zirconates.

Coatings with different boron content were prepared by magnetic field-assisted Co-based laser metal deposition on 300 M ultra-high strength steel. The effects of boron content on the magnetic properties, mechanical properties, friction and wear properties, and corrosion resistance of the coating were investigated. The research results indicate that adding 6 wt% of boron to cobalt alloy in a 35 mT alternating magnetic field is beneficial for refining the microstructure, which can improve the mechanical properties of the coating. This research also discusses the effect of boron content on the wear and corrosion resistance of the coating. The results show that adding boron content enhances the magnetostrictive effect, and reduces the elastic modulus of the laser metal deposition coating while ensuring its hardness, thereby improving the wear and corrosion resistance of the laser metal deposition layer. The hardness of the coating can reach 1215 HV. The friction coefficient and corrosion current density of the coating are reduced by 26.9% and 60.2% respectively compared with the substrate. This work can help promote the application of laser metal deposition technology, reduce costs, and ensure performance.

In this paper, the MIG welding process is utilized to weld a 3 mm thick 5052 aluminum alloy plate by using ER5356 welding wire as filler. The effects of different welding speeds on the microstructure and mechanical properties of the weld are systematically studied utilizing a metallographic microscope, x-ray diffractometer, scanning electron microscope, room temperature tensile, and microhardness. It was found that there were pore defects in the samples at lower or higher welding speeds, and there was no penetration at the maximum welding speed. When the welding speed is 650 mm min ^−1 , the weld is well-formed, the surface is flat without pores, the fish scale is evenly distributed, and the weld shows good penetration. The intermetallic compounds of all the welds are mainly composed of α (Al), Mg _2 Si, Al _3 Fe, and Al _3 Mg _2 . The mechanical properties of the samples show that the hardness of the weld reaches the maximum value of 56.7HV at this welding speed, and the tensile strength and elongation are 210 MPa and 14.3%, respectively. The fracture is located at the junction of the base metal and the heat-affected zone, and the fracture type showed typical ductile fracture.

The high-temperature lead-bismuth eutectic (LBE) corrosion resistance and ring compression performance of the Fe15Cr11Al2Si, Fe15Cr11Al0.5Y, and Fe15Cr11Al2Si0.5Y coatings were investigated. Even if the corrosion test temperature reaches 800 °C, all these coatings can effectively protect the steel cladding tube. After the corrosion test temperature exceeded 660 °C, an obvious Al-rich oxide layer was formed on the surface of the coating, and Al element enrichment occurred at the interface between the coating and the substrate. After the corrosion test at 800 °C, holes appeared in the thick interface layer of the Fe15Cr11Al2Si0.5Y coating. The Fe15Cr11Al2Si coating cracked after the ring compression test with a deformation rate of 3%, and the coating peeled off after the deformation rate reached 5%. When the deformation rate reached 5%, there was still no cracking in the Fe15Cr11Al0.5Y coating. When the deformation rate reached 30%, the coating cracked, but the cracked coating was still tightly bonded with the substrate. The Fe15Cr11Al2Si0.5Y coating has the worst compression performance, even if the deformation rate is 1%, the coating still peels off obviously. The underlying mechanism for the evolution of corrosion resistance and compression performance was discussed.

Aluminum-based metal matrix composites (AMMCs) find extensive applications in aerospace, defence, automotive, and various sectors on account of remarkable mechanical properties, lightweight nature, and excellent dimensional stability. In this research, AA7075 matrix material was reinforced with tungsten carbide ceramic particles with various 0, 5, 10, 15 and 20 weight percentages (wt%) with the use of Ultrasonic assisted stir casing setup. The stir casted AA7075 MMCs were subjected to XRD, SEM, and density test to investigate the presence of elements, microstructure and density. The tensile, micro hardness, and wear test were performed on AL7075 based MMCs after conducting NaCl based spray test at the condition of spray pressure of 1.2 kg cm ^−2 , spray duration of 120 h and PH value of 8.2 to determine the wear resistance, micro hardness and Ultimate Tensile Strength. The XRD test confirmed the presence of secondary phases such as Al _2 Cu, W _2 C, and MgZn _2 with Al and WC phases. The SEM test confirmed the uniform dispersion and no more cluster formation upto 15 wt% WC addition and agglomeration of WC was occurred in the addition of 20 wt% of WC. The enhancing of wt% of WC improved the corrosion resistance, Micro hardness, UTS, wear and up to 15 wt% addition and decreases by the 20 wt% WC addition. The higher tensile strength 312 MPa was obtained from AA7075/15 wt%WC composite. The lower wear rate 0.11 mg m ^−1 was obtained from AA7075/15 wt%WC at 1000 m sliding distance with 1.2 m s ^−1 sliding velocity. The improved mechanical and tribological properties were mainly depended on strengthening mechanisms such as load transfer mechanism and dislocation strengthening mechanism.

Large-tube forgings were formed using nine layers of continuous-casting billet made from 15CrNi3MoV alloy steel via additive forging. The interfacial microstructural evolution under different hot-compression bonding temperatures and strains was investigated using optical microscopy, scanning electron microscopy, and electron backscatter diffraction. The tensile properties of the hot-compression-bonded and tube-forged samples were also evaluated. The results showed that as the hot-compression bonding temperature and strain increased, the bonding interface gradually disappeared and the voids at the bonding interface closed. Finally, the interface was replaced with recrystallised grains. The tensile properties of the hot-compression-bonded samples at different temperatures and strains were identical. The tensile properties of the interface and base samples of the tube forging were comparable, and the fracture morphologies were consistent. The fracture position of the large tensile sample with a length of 1000 mm containing three original interfaces is the base, indicating the complete metallurgical bonding of the forging.

This study aims to examine the effects of waste material more especially horse hair as fiber on mechanical and physical properties. Tensile, flexural, impact, and hardness properties of horse hair fiber and titanium dioxide nanoparticles (TiO _2 NPs) polyester composite were investigated to determine whether the latter might be used as a new material in various engineering applications for a longer life. To improve the impact resistance of the composite, horse hair fiber is mixed in different ratios with titanium dioxide and polyester as filler. Tensile, flexural, and impact mechanical properties were assessed using the Universal Testing Machine, the Rockwell Hardness Testing Machine, and the Izod Impact Test. Specimens were hand-put up using various fiber weight ratios. The results of this study showed that Specimen 5 showed a tremendous increase in flexural strength (98.87 MPa), tensile strength (91.46 MPa), hardness (115 HV), impact strength (15.98 J m ^−1 ), and water uptake (10.18%) as compared to the neat and also with the other Specimens. Scanning electron microscopy (SEM) was used to investigate the fracture surface in more detail in order to search for failure mechanisms and the dispersion of nanoparticles. SEM micrographs verified the uniform dispersion of the nanoparticles. Results suggest that these composites can be used as a material for a variety of applications, including biological claims that they are a practical, durable, and environmentally friendly choice.

Hot deformation behavior of as-sintered Fe-2.1Cu-0.5C alloy was evaluated through the construction of constitutive equations and a hot processing map. The hot deformation behavior was investigated at different temperatures and strain rates and microstructure observations were subsequently conducted. Flow stress for the initiation of dynamic recrystallization mechanism was determined. Tensile and fatigue strength tests were conducted at room temperature. It was observed that the microstructure of the alloy forged at lower temperature exhibited smaller grain size and its grain size increased with higher forging temperatures. Mechanical testing results revealed that an increase in the forging temperature led to a lower tensile strength and a higher fatigue strength. This change can be attributed to the larger grain sizes and the reduction of microcracks. A forging temperature at 1050 °C was recommended to achieve optimal mechanical properties for powder forged Fe-2.1Cu-0.5C products. These results might give some hints for optimizing process conditions and improving mechanical properties of powder metallurgy alloys by the use of constitutive equations and thermal processing maps.

In this study, a comprehensive investigation was conducted to explore the microstructural evolution, texture characteristics, and mechanical properties of extruded Mg-9Gd-3Nd-1Zn-1Sn-0.5Zr alloys with varying extrusion ratios (ERs). Moreover, the high-temperature mechanical properties of the alloy and analyzed the corresponding fracture mechanisms were investigated. The findings unveiled a refinement in grain size and an improvement in homogeneity with increasing ER. Such refinement coincided with the disruption of coarse Mg _5 (Gd, Nd, Zn) eutectic phases, facilitating dynamic recrystallization. As a result, the extruded alloy manifested small grains, significant orientation difference in grain boundaries, and a weakened texture. In particular, the average grain size in the extrusion direction (ED) diminished to 13.29 μ m (ER4), 9.62 μ m (ER16), and 4.05 μ m (ER25). And the ED texture of the ER4 alloy featured a strong (0001) basal bimodal pattern, whereas the ER16 and ER25 alloys showcased a random texture. Furthermore, the ER25 alloy displayed notable work hardening at temperatures of 200 °C or below, exerting a significant influence on its stress–strain curve. The ultimate tensile strength (UTS) of the alloy remained consistently above 275.09 MPa, demonstrating ductile fracture characteristics characterized by numerous dimples at temperatures of 200 °C or higher. The study identified the second phase as the primary contributor to enhancing the high-temperature tensile characteristics of the alloy. In summary, this research developed a unique high-strength Mg-9Gd-3Nd-1Zn-1Sn-0.5Zr alloy characterized by fine grain and texture strengthening. The alloy exhibited remarkable stability at temperatures of 250 °C or lower, making it a promising candidate for applications in high-temperature applications.

In this study, the austenitic, corrosion-resistant N50 steel alloyed with different nitrogen, niobium and vanadium content was investigated. This steel is used in the production of high-strength, cryogenic pipes. The production process for these pipes involves aging at 650 °C–665 °C for 50–100 h. Therefore, steels were examined in their as-delivered state, after aging at 650 °C, 100 h and after solid solution heat treatment. The structure of the steel was analyzed using optical and scanning microscopy, tensile and impact strength tests were conducted at room temperature and at −196 °C. It was found that the total volume fraction of the precipitated phase after aging is more dependent on the total concentration of nitride-forming elements—Nb and V, than on nitrogen. Aging does not affect the basic operational properties at room temperature, but it can significantly affect toughness at −196 °C.

Gas carburizing significantly enhances the surface properties of low-alloy gear steels, resulting in superior micro-hardness, layer thickness, carbon content, and overall mechanical properties. Unlike other thermochemical processes such as nitriding and carbonitriding, which have limitations in core properties and hardening depth, gas carburizing offers unmatched surface hardness, wear resistance, and mechanical strength. This makes it ideal for demanding applications in the automotive, aerospace, and manufacturing industries. In this research, samples were gas-carburized for 4, 6, or 8 h. The results showed significant improvements: micro-hardness increased from approximately 140 HV to over 819 HV, and the surface layer thickness grew by more than 41%, from 1166 μ m to 1576 μ m. Additionally, the carbon content in the surface layer increased by over 450%, reaching up to 0.94 wt%. Clear correlations were observed between the duration of heating and the mechanical properties. Longer heating times, particularly after 8 h, raised ultimate tensile strength from 427.29 MPa to 778.33 MPa, while simultaneously decreasing elongation from 26.07% to 2.88% and resilience from 180 J cm ^−2 to 6.66 J cm ^−2 . This optimization not only enhances surface hardness and durability but also improves key mechanical properties such as tensile strength, stiffness, resilience, and overall mechanical performance.

Hastelloy X (HX) alloys with ideal strength and ductility match can be obtained by selective laser melting (SLM) and a proper follow-up heat treatment. This work studies the influence of scanning speed on grain size, grain boundary distribution, recrystallization and mechanical properties of as-built HX. These influences are reevaluated after a solution treatment at 1175 °C for 4h. The results reveal that the average grain size decreases, while the aspect ratio, texture intensity and the proportion of high-angle grain boundaries (HAGBs) increases with the increase of scanning speed. A small amount of recrystallization has occurred in the as-built alloys due to the cyclic thermal effect of SLM scanning. The finer grains and larger aspect ratio imply the higher energy storage during SLM, which will increase the recrystallizing nucleation rate. Solution treatment eliminates the fiber texture of 〈100〉//BD, significantly increases the HAGBs fraction and recrystallization fraction, reduces the grain aspect ratio, and coarsens the grains. With the increase of scanning speed, the strength of the Hastelloy X increases and the elongation decreases. The decrease of grain size is the main reason for the increase of yield strength.

Over the past two decades, there has been a remarkable surge in the utilization of composites, with fiber-reinforced polymer composites gaining significant traction owing to their commendable structural performance. Concurrently, extensive research has been conducted to assess the behavior of composite materials, focusing on various parameters such as fiber type, lamination order, matrix type, and the inclusion of filler materials. In this study, we investigated the mechanical properties of flax (F)/ramie (R) epoxy hybrid composites, specifically exploring the effects of different lamination sequences. Four distinct lamination sequences were chosen: FFRR, FRFR, FRRF, and RFFR. The composites were fabricated using compression molding techniques, adhering to ASTM standards for the evaluation of mechanical properties including tensile strength, flexural strength, impact strength, and interlaminar shear strength. Among the laminate sequences studied, FRFR exhibited the lowest void content at 4.76%, while RFFR composites showed the highest void content at 16.67%. The most favorable results were observed with FRFR composites, boasting a tensile strength of 77.06 MPa, impact strength of 13.36 kJ m ^−2 , and interlaminar shear strength of 8.13 MPa. Notably, the FFRR composite exhibited the highest flexural strength at 118.09 MPa. Additionally, scanning electron microscopy (SEM) analysis was conducted to investigate surface morphology and identify reasons for failure.

Lightweight porous materials with high load-bearing, damage tolerance and energy absorption (EA) as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications, e.g. aerospace, automobiles, electronics, etc. Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient, enabling stress homogenization, significant load bearing, and damage tolerance to protect the organism from high external pressures in the deep sea. This work illustrated that the complex hybrid wave shape in cuttlebone walls, becoming more tortuous from bottom to top, creates a lightweight, load-bearing structure with progressive failure. By mimicking the cuttlebone, a novel bionic hybrid structure (BHS) was proposed, and as a comparison, a regular corrugated structure and a straight wall structure were designed. Three types of designed structures have been successfully manufactured by laser powder bed fusion (LPBF) with NiTi powder. The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4 μ m. Microstructural analysis indicated that the LPBF-processed BHS had a strong (001) crystallographic orientation and an average size of 9.85 μ m. Mechanical analysis revealed the LPBF-processed BHS could withstand over 25 000 times its weight without significant deformation and had the highest specific EA value (5.32 J·g ^−1 ) due to the absence of stress concentration and progressive wall failure during compression. Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity. Importantly, the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated (over 99% recovery rate). These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.

In this study, tantalum carbide (TaC) was synthesized using an innovative approach that synergistically integrates mechanosynthesis and electric arc furnace processes. By employing high-energy ball-milling (HEBM) for 50 min under environmental conditions, TaC-WC powders were successfully synthesized, using a powder mixture of tantalum and carbon in a 1:1 stoichiometric ratio. This method yielded a composition of 72.5 wt% TaC and 27.5 wt% WC, with an average particle size of 0.7 ± 0.3 μ m. The use of an electric arc furnace led to the fabrication of a highly dense material with a relative density above 98%. Notably, WC derived from the mechanical milling material served as an effective sintering aid. x-ray photoelectron Spectroscopy (XPS) results indicated the formation of metal oxides on the surface of the sample, and despite the presence of these oxides, the density of the material remained uncompromised. Furthermore, x-ray diffraction (XRD) analysis after the electric arc furnace treatment demonstrated the preservation of the TaC and WC phases. Mechanical properties, including Vickers hardness, Young’s modulus and fracture toughness were 22.8 ± 0.5 GPa under an applied load of 9.8 N, 539 GPa and 6.6 MPa m ^1/2 , respectively. The results underscore a novel and efficient synthesis route for TaC-WC with enhanced mechanical properties and high density, which are crucial aspects for applications in ultra-high temperature ceramics.

Ceramic oxides, renowned for their exceptional combination of mechanical, thermal, and chemical properties, are indispensable in numerous crucial applications across diverse engineering fields. However, conventional manufacturing methods frequently grapple with limitations, such as challenges in shaping intricate geometries, extended processing durations, elevated porosity, and substantial shrinkage deformations. Direct additive manufacturing (dAM) technology stands out as a state-of-the-art solution for ceramic oxides production. It facilitates the one-step fabrication of high-performance, intricately designed components characterized by dense structures. Importantly, dAM eliminates the necessity for post-heat treatments, streamlining the manufacturing process and enhancing overall efficiency. This study undertakes a comprehensive review of recent developments in dAM for ceramic oxides, with a specific emphasis on the laser powder bed fusion and laser directed energy deposition techniques. A thorough investigation is conducted into the shaping quality, microstructure, and properties of diverse ceramic oxides produced through dAM. Critical examination is given to key aspects including feedstock preparation, laser-material coupling, formation and control of defects, in-situ monitoring and simulation. This paper concludes by outlining future trends and potential breakthrough directions, taking into account current gaps in this rapidly evolving field.

MAG welding of 07MnMoVR steel was performed at the 2G and 3G positions, and weld formation, microstructure, residual stress, and tensile properties were compared. In this study, welds without defects were obtained at the 2G and 3G positions. The results showed that a larger distortion of the weld at the 3G position was present because of the higher heat input and that the perlage morphology was related to the introduction of the arc weaving process. In addition, the grain size of the filling pass was coarser than that of the cap pass because of the repeated heating process, and the grain sizes of the filling and cap passes increased by approximately 33% for the weld at the 3G position compared with that at the 2G position. In this case, the weld at the 3G position showed a larger residual stress and lower yield and tensile strengths, and the elongation rates and microhardness of the weld at the 3G position were lower than were those of the weld at the 2G position, regardless of the root pass, filling pass, or cap pass.

Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials, especially for alloys with complex phase constituents and heterogenous microstructure. However, the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment processes. Herein, we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys, and a wire arc additively manufactured (WAAM) Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility verification. Through this method, the optimal microstructures (fine grain, controllable amount of long period stacking ordered (LPSO) structure and nano-scale β ′ precipitates) and the corresponding customized heat treatment processes (520 °C/30 min + 200 °C/48 h) were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%, which surpassed those of other state-of-the-art WAAM-processed Mg alloys. Furthermore, we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scale β ′ precipitates were present. It is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.

The particle size and morphology of crushed stones impact their macroscopic mechanical and physical properties, which has become a hot topic in the study of road and geotechnical engineering. However, some reported studies fail to control the particle morphology as the only independent variable. This paper presented a new method to print artificial aggregates based on 3D printing technology of particles. The applicability of the new method was verified with uniaxial compression and dynamic modulus tests of asphalt mixtures formed by the printing aggregates. Results showed that the printing aggregates earned similar physical properties to real coarse when sintered at 1400 °C with alumina ceramic powder and CuO: TiO _2 a 1:2 additive in mass. Besides, the gross volume density, compressive strength, and shrinkage of the printing aggregates show a similar trend of increasing and then decreasing with the increase of additives. The optimal mass percentage of additives was obtained to be 5%. Mechanical tests indicated that the mechanical indexes of the asphalt mixtures formed with the two types of coarse aggregates were similar, while the results of the specimens formed with artificial coarse aggregates showed less dispersion. The stability of test results was significantly improved for different asphalt mixture specimens prepared with 3D printed coarse aggregate. This provides a basic method for further research on the multi-scale properties of particle material.

Innovative pulsed current-assisted multi-pass rolling tests were conducted on a 12-roll mill during the rolling deformation processing of SUS304 ultra-thin strips. The results show that in the first rolling pass, the rolling reduction rate of a conventionally rolled sample (at room temperature) is 33.8%, which can be increased to 41.5% by pulsed current-assisted rolling, enabling the formation of an ultra-thin strip with a size of 67.3 μ m in only one rolling pass. After three passes of pulsed current-assisted rolling, the thickness of the ultra-thin strip can be further reduced to 51.7 μ m. To clearly compare the effects of a pulsed current on the microstructure and mechanical response of the ultra-thin strip, ultra-thin strips with nearly the same thickness reduction were analyzed. It was found that pulsed current can reduce the degree of work-hardening of the rolled samples by promoting dislocation detachment, reducing the density of stacking faults, inhibiting martensitic phase transformation, and shortening the total length of grain boundaries. As a result, the ductility of ultra-thin strips can be effectively restored to approximately 16.3% while maintaining a high tensile strength of 1118 MPa.Therefore, pulsed current-assisted rolling deformation shows great potential for the formation of ultra-thin strips with a combination of high strength and ductility.

Joining steel and aluminum is vital for lightweight automobile but still challenging due to their different physical properties. Herein, resistance spot welding tests were performed on CP780 high-strength steel (thickness 1 mm) and 7075 aluminum alloy (thickness 1.5 mm) dissimilar metals under steady-state magnetic field. The influences of magnetic field (B = 40 mT) on the structure of welded joints, the phase composition/content of intermetallic compounds, and tensile properties of welded joints were analyzed under different welding current conditions (I = 9 kA,10 kA, 11 kA, and 12 kA). At the same welding current, the Lorentz force generated by the additional magnetic field promoted the outward circumferential movement of the molten metal in the weld along the horizontal surface , as well as increased the diameter of the Fe/Al contact interface in the weld nugget along the horizontal direction, conducive to the effective utilization of heat of the resistance spot welding. Except under (11 kA-0 mT) and (11 kA-40 mT), welded joints under other welding parameters displayed a few welding defects, such as incomplete fusion and shrinkage cavity formed at the cross-section of the welded joints. Therefore, the synergism between the magnetic field and appropriate welding current held important roles in the formation of welded joints without obvious welding defects. The intermetallic compounds of all the welds were mainly composed of (Fe, Si)Al _2 and (Fe, Si)Al _5 . Meanwhile, the thickness and content of the intermetallic compounds layer reduced under a magnetic field at the same welding current, significantly improving the tensile properties of the welded joints. The comprehensive properties of welded joints were the best under 11 kA-40 mT, with an average shear force increase from 3.02 kN to 3.49 kN (15.56%) and an average displacement increase from 1.01 mm to 1.22 mm (20.79%). Overall, the proposed dissimilar aluminum/steel resistance spot welded joint assisted by magnetic field looks promising for lightweight automobile use.

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

This study focuses on the effects of preparing conditions of gelatin/carboxymethyl cellulose (CMC) composites on their mechanical properties of gelatin/carboxymethyl cellulose (CMC) by extreme gradient boosting (XGB) machine learning algorithm. The research involved studying the effect of weight fraction of carboxymethyl cellulose (CMC) and graphene oxide (GO) as well as the concentration of ethyl(dimethylaminopropyl)carbodiimide (EDC)/ N-hydroxysuccinimide (NHS) on modulus, % strain at break and ultimate tensile strength (UTS). It also includes a correlation heatmap, feature importance assessment, model performance evaluation, and the Shapley Additive Explanation (SHAP) technique to analyze the dataset. The relationship between independent parameters and mechanical properties reveals insights into the material’s ductility, flexibility, and modulus. Feature importance demonstrates that NHS/EDC concentration has the highest impact on the mechanical properties. Increase of EDC/NHS concentration is observed to drastically elevate the modulus and UTS, however, reduces the flexibility of the nanocomposites. CMC improves flexibility but reduces UTS and modulus. GO improves % strain at break, UTS and modulus up to 1% GO, however, higher wt% of GO reduces the mechanical performance. With lower concentrations of NHS/EDC, the mechanical properties can be tailored for soft tissue engineering applications. The study highlights the importance of optimizing material compositions for tissue engineering applications.

Petroleum-based polymers pose significant environmental challenges; this prompts researchers to seek alternatives for the same. The foremost solution to replace petroleum-based packaging lies in bio-based polymers that can degrade with water, soil, and the environment. The most common and economical bio-based polymer today is polyvinyl alcohol (PVA), however, it has certain limitations such as brittleness, hydrophilic nature, etc. The primary objective of this study is to enhance the flexibility, transparency, barrier properties, and thermal stability of PVA by incorporating glycerol as a plasticizer. In this regard, thin films were prepared by utilizing a solution-casting technique (blade coating) upon the addition of numerous concentrations of glycerol ranging from 1 to 5 wt%. Here two sets of thin films were prepared i.e., with glycerol (modified) and without glycerol (pure PVA). Results suggest exceptional mechanical flexibility and enhanced optical properties in terms of improved transmittance (>90%) upon incorporation of glycerol into PVA. The modified films also demonstrated a significant increase in their water barrier capabilities in comparison to pure PVA films. When the concentration of glycerol reached to 5 wt%, a substantial increase in biodegradability and flexibility was witnessed resulting in reduced brittleness. Thus, the mechanical properties of the modified thin films exceeded that of pure PVA counterparts. The prepared thin films unveil exciting possibilities to be used in diverse applications; such as food packaging, membranes, biodegradable materials, etc,. The extensive discussion is presented in the light of observed results.

Metal matrix composites (MMC) have advantages over polymer matrix composites such as high stiffness and strength, high-temperature resistance, better abrasion resistance, creep resistance, resistance to degradation by fluids, dimensional stability, and non-flammability. Metal matrix composites are used for various applications in the automotive, aerospace and sporting goods industries. The primary objectives of the current research work encompass the fabrication of Metal Matrix Composites (MMCs) AZ31 with 0.5%, 1.0% and 1.5% zirconium boride (ZrB _2 ) nano-powder by the stir casting process, followed by welding through Friction Stir Welding (FSW). The metallographic analysis was carried out on the weldments of all cases. The macroscopic and microscopic analysis confirmed the defect-free weld joint. Tensile and hardness tests were conducted to study the mechanical properties of the materials. The tensile strength and the percentage of elongation increased with the percentage of ZrB _2 . But, after 1.0% addition of nano particles the strength decreased. The same pattern had been observed in both base and welded samples. The defect-free welding joints were fabricated with an efficiency of 79.1%, 79.7% and 77.7% for the materials with 0.5%, 1.0% and 1.5% nano powder, respectively. EIS and PDP tests were conducted in 3.5% NaCl to study the corrosion behaviour of base and welded materials. The corrosion tests on the base MMC samples showed that the corrosion resistance increased after the addition of ZrB _2 nanoparticles. In addition, the corrosion resistance of all the welded samples improved compared with their respective base materials.

The properties of basalt fiber reinforced polypropylene composites (BF/PP) were improved by ultrasonic treatment of resin building pressure to assist melt impregnation. Combined with the study of ultrasonic pressure building theory, the mechanical properties of the modified composites were analyzed using the characterization of tensile, flexural and impact strengths in response to porosity and fracture rate. The effects of ultrasonic power, frequency and distance of action on resin building pressure and composite properties were investigated. The results showed that the best effect was achieved when the ultrasonic frequency was 25 kHz, the ultrasonic power was 300 W, and the action distance was 4 mm, at which time the porosity of the prepreg was reduced to 2.99%, the fracture rate was 3.36%, and the tensile, flexural, and impact strengths were 108.73 MPa, 116.81 MPa, and 51.59 KJ.m ^−2 .

To study the effect of different super absorbent polymer (SAP) mixing methods on mechanical and shrinkage properties of internal curing concrete, SAP mixing mode was used as the study variable, and simulated the bridge leveling structure. The flow performance test, mechanical performance test, free shrinkage test, restrained shrinkage test and scanning electron microscope observation test were carried out on the internal curing concrete. The influence of different mixing methods on the flow properties, mechanical properties, shrinkage properties and microstructure of internal curing concrete were analyzed. The results showed that the amount of mixing water had a great influence on the fluidity when adding pre-absorbent SAP; The effect of SAP on the mechanical properties is minimal when the dosage is 0.2% of the mass of cementing material; Pre-absorbent SAP has the best effect on improving shrinkage cracks of concrete; SAP stored water at the initial stage of hydration, promoted the generation of hydrolysis products, prolong the hydration process, filled the gap inside the concrete, and improved the anti-cracking performance. It is recommended that SAP should be partially pre-absorbed.

In order to improve the comprehensive mechanical properties of the welded joints of the 5A06 aluminum alloy, friction stir welded (FSW) joints were subjected to deep cryogenic treatment (DCT). The microstructure and mechanical properties were characterised using metallographic microscopy, x-ray diffractometer (XRD), energy spectrometer, microhardness tests, and tensile tests. The experimental results show that DCT refines the structure significantly due to the large temperature difference. This refinement results from an increase in Mg atoms within the α -Al solid solution through the precipitation of Al atoms, forming the Al _3 Mg _2 phase. This enhancement in plasticity is achieved through dispersion distribution. Moreover, as the treatment time of DCT increases, the mechanical properties of the welded joint also improve significantly. The microhardness of the welding joint peaked at DCT3h, rising from 78.8 HV at DCT0h to 87.2 HV at DCT3h. Meanwhile, the tensile strength of the joint reached its maximum at DCT12h, rising from 358.7 MPa at DC0h to 385.3 MPa at DCT12h, representing a 7.4% increase. These experimental results underscore the significant impact of DCT on improving the welded joints.

The effects of annealing temperature on the recrystallization and grain boundary distribution characteristic for the drawn microtube of GH4169 alloy were studied by scanning electron microscope (SEM) equipped with an electron backscatter diffraction (EBSD) analysis system and transmission electron microscopy (TEM). The results demonstrated that at an annealing temperature of 850 °C, only a small proportion of recrystallization for the microtube underwent. As the annealing temperature increased, the proportion of recrystallization also increased. Specifically, at 900 °C, the proportion reached 95.8%, indicating complete recrystallization. Fine recrystallization grains were obtained with an average grain size of 4.73 μ m. As the annealing temperature is above 900 °C, the microtube also undergo complete recrystallization, and the grains grow up gradually. At 1000 °C, the average grain size grows to 7.42 μ m. The results also revealed that with the annealing temperature increasing, the proportion of Σ 3 grain boundary of the microtube was rising. The proportion of Σ 3 grain boundary increased from 30.1% to 34.2% with the annealing temperature increased from 900 °C to 1000 °C. Moreover, as the annealing temperature increased from 850 °C to 1000 °C, the room temperature tensile strength of the tube decreased from 1323 MPa to 965 MPa, the yield strength decreased from 1054 MPa to 523 MPa, and the fracture elongation increased from 10.2% to 31.2%.

In this study, the parameters of Metal Inert Gas (MIG) and Metal Active Gas (MAG) were investigated of AISI 316L/ER 316L. A quaternary shielding gas mixture consisting of Argon (Ar), Helium (He), Carbon Dioxide (CO _2 ), and Nitrogen (N _2 ) was chosen. The Taguchi orthogonal array (OA-L9) methodology was employed to explore optimal welding settings, including arc current (120A, 160A, 200A), wire feed rate (3, 3.5, 4 m min ^−1 ), and shielding gas combination (G1, G2, G3). The findings highlighted the importance of shielding gas in influencing the ultimate tensile strength (UTS), elongation percentage (EL%), and material toughness of welding joints. Notably, the highest UTS (515.77 MPa), EL% (20.85%), and material toughness (133J) were achieved by the specific group gas combination shown as G1. It is recommended to configure welding parameters to an arc current of 160A, a wire feed rate of 4 m min ^−1 , and the G1 gas combination. Welded specimens using a G1 gas mixture showcased the best UTS and EL%. Additionally, it was found that the fusion zone (FZ) and heat-affected zone (HAZ) hardness are most profoundly influenced by the choice of gas combination (G2), resulting in the best hardness values of 253.79 HV and 239.68 HV, respectively. The optimal parameters for achieving the desired material hardness were precisely identified as (120A, 3 m min ^−1 , G2). These insights offer a pathway to enhance welding performance and, in turn, elevate the quality and efficiency of industrial applications.

This study aims to extract and characterize cellulose nanocrystals (CNCs) from soybean hulls, and investigate their application as reinforcement in fishtail palm leaf stalk fiber (FPLSF) composites. CNCs were extracted through a multistep process involving alkalization, bleaching, acid hydrolysis and mechanical fibrillation. Analysis confirmed the transformation of cellulose I to cellulose II, yielding nanocrystals with 70.58% crystallinity index and thermal degradation peak at 371 °C. FTIR analysis verified removal of lignin and hemicellulose after extraction. The extracted CNCs were incorporated into FPLSF-epoxy composites at 2.5-10 wt% loading. Results showed 7.5 wt% CNCs (FT/SH4) provided optimal mechanical properties, with 51.4 MPa tensile strength, 46.09 MPa flexural strength and 36.47 kJ mm ^−2 impact strength. Lower CNC percentages showed significantly inferior properties due to poor fiber-matrix interfacial bonding. Overall, extracted soybean hull CNCs demonstrated good reinforcement capabilities for natural fiber composites. This provides a sustainable application route for agricultural residues and contributes to the development of high-performance biocomposites.

Developing high entropy alloys (HEAs) that possess both superior mechanical properties and low cost is a classic challenge in the design of alloys used in engineering applications. In this work, a series of Co-free Al _x Ti _(9– _x _) (CrFeNi) _91 ( x = 0, 3, 6, and 9 at%, denoted as Al x Ti(9- x ) hereafter) HEAs were designed to investigate the influence of Al and Ti elements on the microstructure and mechanical properties of the FCC-structured CrFeNi alloy and pursue a considerable strength-plasticity balance. Massive precipitates with a nano-scale but different morphology and/or structure formed in the inter-dendritic region of alloys. The morphology of precipitates was strongly linked with the variation in the relative content of Al and Ti elements, which varied from a granular shape (ordered BCC structure) in Al9 and Al6Ti3 alloys to a strip shape (HCP structure) in Al3Ti6 alloy. With an increase (decrease) in Ti (Al) content, the yield strength of alloy significantly improved, which benefited from the combined effect of solution strengthening and precipitation strengthening, but the elongation dropped sharply. Compared to the same amount of Al element, Ti element contributed to the improvement of strength but deteriorated the plasticity of alloy. Thereinto, Al6Ti3 alloy presented a relatively favorable strength-plasticity balance with a yield strength of 768 MPa and an elongation of 10.2%. Apparently, only the moderate amount of Al and Ti elements helps to the favorable configuration of strength and plasticity. The findings in this work provide a distinct insight into the design and optimization of Co-free HEAs as the structural applications.

In this paper, the Mg-9.32Gd-3.72Y-1.68Zn-0.72Zr (wt%) alloy has undergone three times of repetitive upsetting extrusion deformation. Alloys with different morphologies and distribution patterns of the second phase have been prepared by varying the deformation temperature in each pass. The effects of the second phase on microstructure, texture and mechanical properties are investigated. The results show that (i) the second phase, including Mg _5 Gd and LPSO phase, has an important effect on the dynamic recrystallization (DRX) behavior of the alloy. (ii) Appropriate lamella distance and block phase size can promote the activation of the slip system and effectively weaken the texture strength. (iii) The DT sample has an effective combination of fine grain strengthening and second phase strengthening due to the reasonable second phase distribution and size, which greatly improves the UTS and YS of the alloy.

With increasing requirements for environmental protection and energy conservation, Al–Cu powder alloys play an important role in machine weight reduction. During the preparation of the Al–Cu powder alloy, an appropriate sintering temperature helps improve the comprehensive performance of the alloys. In this study, powder metallurgy was used to prepare Al–7.5Cu–1Si alloys, and the effects of different sintering temperatures on their relative sintering density, hardness, and tensile strength were studied. The microstructure and phase composition of the alloy were observed and analyzed by scanning electron microscopy and x-ray diffraction, and the mechanical properties of the alloy were studied using a Brinell hardness tester and a universal material testing machine. By analyzing the microstructural changes of the alloys at different sintering temperatures, the optimal sintering temperature of the alloy was determined to obtain the best properties. The results demonstrated that the sintering temperature significantly affected the diffusion and migration of the metal particles inside the alloy. When the temperature was low, numerous pores were present in the alloy, and the degree of bonding between the metal particles was poor. As the temperature increased, the number of pores in the alloy decreased, and good metallurgical bonding occurred between the particles. The relative densities and mechanical properties of the alloys were significantly affected by the sintering temperature. When the temperature was below 570 °C, the relative density and mechanical properties were low. At 590 °C, the alloy underwent deformation and was in an over-sintered state. The best sintering temperature was 570 °C. This is because at this temperature, the relative sintering density, hardness, and tensile strength of the alloy all reached maximum values, which were 98.6%, 71 HB, and 153 MPa, respectively.

In order to use high alumina coal gangue as auxiliary cementitious admixture via a simple and convenient thermal activation technique, the thermal transformation, mineral phase transformation and structure changes of coal gangue at calcining temperatures of 500–1000 °C were analyzed using x-ray diffraction (XRD), differential thermal Analysis (DTA), thermogravimetry (TG), infrared analysis (IR) and scanning electron microscope (SEM). The mechanical properties of cement mortar with 30% coal gangue auxiliary cementitious admixture were also measured to determine the optimal calcining temperature. As calcining temperature was increased, the coal gangue experienced the following transformations: carbon combustion, dehydroxylation, metakaolin transformation and mullite transformation. The cement mortar with coal gangue auxiliary cementitious admixture calcined at 700 °C presented the highest 28-d flexural and compressive strength, increasing by 8.27% and 11.85% respectively as compared with the benchmark cement mortar. The maximum dosage of coal gangue auxiliary cementitious admixture in cement mortar was further identified to be less than 30% by mechanical properties testing. The activity of high alumina coal gangues at different calcining temperatures was explained from the view points of hydration degree and products. The present investigation can provide a useful reference to utilize high alumina coal gangue as auxiliary cementitious admixture by means of a simple thermal activation at 700 °C.

This work presents a systematic first-principles study of the crystal structure, mechanical, electrical, optical, and thermodynamic properties of lithium- and calcium-based catalysts (Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 ) for the production of cubic boron nitride. The mechanical findings indicate that Ca _3 N _2 is identified as a ductile material, with a higher B/G (20.04) and Poisson’s ratio (0.48). The other three materials are recognized as brittle materials, with B/G less than 1.75 and Poisson ratio less than 1/3. The electrical discoveries show that Li _3 BN _2 has the widest band gap among the four catalyst materials, and the band gap of ternary catalyst materials (Li _3 BN _2 and Ca _3 B _2 N _4 ) is larger than that of corresponding binary catalyst materials (Li _3 N and Ca _3 N _2 ). The optical results reveal that Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 have sufficient energy to prevent charge carriers from being scattered or captured by material defects. The absorption peaks of Ca-based materials (Ca _3 N _2 and Ca _3 B _2 N _4 ) are significantly higher than those of Li-based materials (Li _3 N and Li _3 BN _2 ). In this frequency range, the light is the most difficult to pass through in Ca _3 N _2 and the easiest to propagate in Ca _3 B _2 N _4 . The connection between Li _3 N and Ca _3 N _2 bands is greater, while the Li _3 BN _2 and Ca _3 B _2 N _4 bands interact rather weakly. The thermodynamic conclusions demonstrate that the thermal stability of the four structures is as follows: Li _3 N< Ca _3 N _2 < Li _3 BN _2 < Ca _3 B _2 N _4 . The heat capacities of Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 tend to approach _2 3.74, 52.05, 70.73, and 311.48 J·mol ^−1 ·K ^−1 , respectively.

Here we present the optoelectronic properties of pure inorganic lead-free halide perovskites in the form of Cs _2 AgBi X _6 ( X = Br, Cl, F, I) using the density functional theory calculations on cubic phase (Fm $\mathop{3}\limits^{̅}$ m) and tetragonal phase (I4/m). First, all the structures of the two phases were optimized at the PBE level. Structural, electronic, optical properties, phonon, and thermal properties of Cs _2 AgBi X _6 in cubic (Fm $\mathop{3}\limits^{̅}$ m) and tetragonal phases (I4/m) were obtained using the VASP code. Tetragonal phases of all compounds of the form Cs _2 AgBi X _6 , except Cs _2 AgBiBr _6, are reported here for the very first time. Among all the Cs _2 AgBi X _6 ( X = F, Cl, Br, I) structures, the cubic phase of Cs _2 AgBiBr _6 was seen to have the highest absorption coefficient along with prominent electronic features that are favorable for optoelectronic applications. Thus, the cubic phase of Cs _2 AgBiBr _6 was selected as the host lattice and bromine atoms were partly replaced with chlorine and iodine atoms. Electronic and optical properties of these mixed halide compounds of Cs _2 AgBiBr _6−x F _x , Cs _2 AgBiBr _6−x Cl _x, and Cs _2 AgBiBr _6−x I _x where x = 1, 2, 3, 4, 5 are investigated with hybrid functional HSE06 level. The electronic structure revealed that these mixed compounds exhibited indirect band gap nature regardless of the halide substitution (different x concentration) and the band gap of Cs _2 AgBiBr _6 could be varied with the substitutions of fluorine, chlorine, and iodine atoms. Our in-depth analysis shows that Cs _2 AgBiBr _6 and their mixed halides have the potential to become active double perovskite materials for photovoltaic applications and as photocatalysts for water splitting.

In order to investigate the fatigue behavior of the hydrogen storage material, 30CrMo steel, in a hydrogen environment, an electrochemical hydrogen charging method was employed. Low-cycle fatigue experiments were conducted on the material to obtain half-life stress–strain hysteresis curves, cyclic response characteristics, and strain-life relationships under different hydrogen charging durations. The results indicate that the material exhibited an overall cyclic softening behavior, transitioning from ductile fracture to brittle fracture after hydrogen charging, resulting in a significant reduction in fatigue life. The Manson-Coffin formula was fitted based on material cyclic response characteristics and strain-life relationship curves. Additionally, fatigue toughness and Chaboche kinematic hardening models were fitted based on low-cycle fatigue test data. Finite element analysis was used to validate the accuracy and reliability of the Chaboche kinematic hardening model. The Chaboche kinematic hardening model showed minimal error compared to experimental data and accurately described the influence of hydrogen on the low-cycle fatigue mechanical behavior of 30CrMo steel.

This study evaluated the performance of bentonite plasticized concrete with good deformation coordination as a road base material, to address the poor deformation coordination of rigid base layers in roads. Through tests such as slump, strength, permeability, and scanning electron microscopy (SEM) and x-ray diffraction (XRD), the study analyzed the variations in workability, mechanical properties, and durability of plastic concrete as a base material under different bentonite and cement contents, as well as the underlying micro-mechanisms. The results showed that plastic concrete exhibited good workability, which improved with increased bentonite and cement content. The 28-day mechanical properties of the plastic concrete met the design criteria for road base layers and had features of higher load-bearing capacity, good toughness, slow strength attenuation, and overall integrity. In durability, the increase of bentonite content enhanced the concrete’s permeability, but decreased abrasivenes and shrinkage. From economic, performance, and engineering perspectives, the optimal bentonite and cement contents for the plastic concrete base were in the ranges of 90 kg m ^−3 to 120 kg m ^−3 and 110 kg m ^−3 to 150 kg m ^−3 , respectively.

ZK60 magnesium alloy was prepared by the hot-pressed sintering combined with the hot-extruded technique. The microstructure and mechanical properties evolution of ZK60 alloy with a reduced extrusion temperature from 350 °C to 250 °C were investigated in detailed. The extruded alloy was mainly composed of fine α -Mg grains and MgZn _2 phase. The grains size gradually decreased with a reduction in extrusion temperature, and the yield strength obviously increased accordingly. The alloy extruded at 250 °C exhibited the smallest average grain size of 2.5 μ m and the best combination of strength and plasticity, with a yield strength of 279 MPa and fracture strain of 18.1% in compressive condition, and 263 MPa and 13.7% in tensile condition, as well as a tension-compression yield asymmetry of 0.94. Both the fine grains formed by the continuous and twin induced dynamic crystallization mechanism and the precipitation strengthening contributed to the strength improvement.