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Functionally graded material (FGM) combines two or more constituents in which one gradually varies toward the other along the structure, improving properties. The contribution of this study is to present the characterisation results of an FGM composed of two groups of cutting tool materials, Al2O3-ZrO2 (ceramic-based alumina) and WC–Co (cemented carbide), designed by a thermomechanical model for predicting the residual stress to avoid thermal cracking. The main result comes from the sample manufactured by pulsed electric current sintering (PECS) at 1300 °C, 50 MPa, and a dwell time of 7 min. Microstructure, density, and mechanical and tribological properties were characterised. Two additional experiments were included to support the observations of the main result. Furthermore, homogeneous commercial materials, cemented carbide and aluminium oxide ceramic, were used to compare with the FGM results. Microscopic analysis revealed an eight-layer structure with no cracks. The relative density result indicated a porosity of 5.27%, mainly concentrated in the first layers. Thus, the Vickers hardness values showed that the first layer, rich in alumina-based ceramic (817 HV), was softer than the last layer, rich in cemented carbide (1272 HV). Conversely, the fracture toughness values were higher in the first layer (8 MPa.m1/2) and decreased towards the last layer (5 MPa.m1/2). Variations in properties along the structure were also observed in the scratch test. Scratch hardness increased towards the final layer. The FGM sample exhibited microcutting as an abrasive wear mechanism for the first three layers and a mixture of microcutting and microploughing for the last three layers. Finally, the drag coefficient results indicated greater friction in the first layers because of their toughest characteristics. Although the sample did not achieve full densification, changes in properties were observed; these properties may be improved by adjusting the sintering parameters. [ABSTRACT FROM AUTHOR]

The use of multi-movable containers for extrusion cutting of low-alloy materials can enhance the mechanical properties of cold extrusion. The grain structure becomes denser during extrusion and deformation, and the cross-sectional metal streamlines, which align with the product's geometric contour, remain continuously distributed and unbroken. However, grain size uniformity at the edges can be further improved. This study proposes the utilization of a movable extrusion die to better control the grain size, enhancing the hardening effects of the material as it enters the die through extrusion cutting. The process employs a movable and a stationary container with a step at the boundary near the die discharge port. As the material is pushed inward and downward during forming, multiple cycles induce severe plastic deformation (SPD), altering the grain direction and refining the grain structure. DEFORM-3D simulations and calculations using the Tabor equations were performed, with results subject to experimental evaluation. Both predicted and experimental increases in hardness were similar, confirming the viability of the movable container design. Additionally, the movable container was used to form a bimetal billet comprising a copper core and an aluminum shell, yielding satisfactory results. Product test results confirmed that grain refinement occurred and hardness increased in all experiments. [ABSTRACT FROM AUTHOR]

The significance of biosilica in the silver-grey magnesium (SG-Mg-10% Si) metal is to enhance its mechanical and tribological characteristics. The Bermuda grass was used to make the biosilica. This investigation employed SG-Mg-10%Si and biosilica reinforcement (0, 5, 10, 15, and 20 wt. %) as the composite matrix. Due to increased bonding between the components of the composite, the SG-Mg-10%Si/biosilica composite created by the stir casting process demonstrated remarkable mechanical and tribological qualities. Further testing was done to assess the mechanical and tribological characteristics of the composite specimens, including density, porosity, hardness, tensile strength, and wear rate. SG-Mg-10%Si was contrasted with all these outcomes. The density plummeted at a rate of 1.49 (g/cm3) when the weight percentage of biosilica particles was added. Minimum and maximum hardness values for the composite's 20% of reinforced biosilica particles are 93.4 VHN and 125 VHN, respectively, and the tensile strength is 633.18 MPa. In order to determine the wear rate of SG-Mg-10%Si/biosilica composites, a dry sliding pin-on-disc tribometer was employed. When biosilica particles were added, the rate of wear of the manufactured SG-Mg-10%Si/ biosilica composites gradually reduced. When subjected to loads of 40 N and sliding distances of 1500 m and 2500 m, respectively, the composite with 20wt.% of biosilica reinforcement had improved anti-wear properties of 10.257 mg/m × 10−3 and 13.334 mg/m × 10−3. Field emission scanning electron microscope (FESEM) was utilized to examine how reinforcement was distributed across the matrix and showed the uniform distribution and strong bonding in the composites, together with a visible biosilica reinforcing interface. The benefits of the SG-Mg-10%Si/biosilica composites are enhanced mechanical and tribological properties and utilized in several applications like automobile, aeronautical and space research, sports goods, and medical types of equipment, reduced expenditure, and saved manufacturing time and exertion. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO), applied to light metals such as titanium, aluminum, and magnesium, creates a two-layer coating and has become increasingly important in metal coatings. However, due to the high voltage and temperature of the process, no online instrument could monitor the underlying mechanism. This paper presents a new image proving that the surface of PEO-coated Mg3ZnCa boiled during the process and argues that three hypotheses are involved in the PEO mechanism based on boiling caused by tolerating high voltage during the PEO process, which could explain the current‒voltage diagram of the process. Finally, nanoindentation was used to measure the elastic module and hardness of the PEO layers. The nanoindentation test results revealed the similarity of the elastic module of the outer porous layer and the primary alloy, with values of 40.25 GPa and 41.47 GPa, respectively, confirming that the outer porous layer corresponds to the cold plasma-gas phase formed during the PEO process. [ABSTRACT FROM AUTHOR]

Traditional fabrication of ceramic parts face limitations due to hardness and brittleness, despite of having good mechanical properties. Digital light processing (DLP) additive manufacturing technology offers promising way to fabricate intricate geometry of ceramic parts. To fabricate high performance, maximizing solid loading of ceramic powder is important to reduce the shrinkage and distortion during post-processing. However, it increases viscosity dramatically and makes difficult with material supply during printing process. Therefore, not only increasing the solid loading of ceramic powder but also minimizing random defects during printing process is essential for us to achieve high-quality ceramic parts. In this study, vision-based defect monitoring system using Mask R-CNN model was employed. We classified two types of defects called pinhole and un-even paste and quantify the defect characteristics such as number and size with pixel level. This method provides us the basis of a feed-back system for controlling the process parameters in real time. [ABSTRACT FROM AUTHOR]

The residual stress causes a premature failure of the manufactured product by a directed energy deposition (DED) process. The stress-relief annealing process can effectively decrease the residual stress. However, the research on the stress-relief annealing on residual stress characteristics of the fabricated part by the DED process consisting of heterogeneous materials has hardly performed yet. The goal of this research work is to investigate the effects of the furnace temperature of stress-relief annealing on residual stress and hardness characteristics of heterogeneous materials fabricated from the DED process. The as-built specimen was created by the deposition of Gridur 6 (G6) powders on AISI 1045 substrates using the DED head of DVF-8000AML. The stress-relief annealing process of the as-built specimen was carried out using an electric furnace. The influence of the furnace temperature on the surface morphology, the residual stress of the boundary region and the hardness of top and bottom surfaces was discussed. Finally, proper furnace temperatures of the stress-relief annealing were proposed. [ABSTRACT FROM AUTHOR]

Two types of filler materials, FeCoCrNiMn and Al-10Si-0.3 Mg powder, were utilized to achieve lap welding of 5083 aluminum alloy to DP780 steel using laser deposition welding at various laser powers. By conducting a comparative analysis of the macroscopic morphology, microstructure, hardness, and shear properties of two groups of welded joints, the effects of multi-principal filler material and heat input on the weld formation, microstructure evolution, and shear properties of dissimilar lap joints were evaluated and discussed. An interesting finding was that, compared to the Al-10Si-0.3 Mg powder, the FeCoCrNiMn powder used as filler material had significant advantages in reducing the hardness of the weld zone and improving the shear properties of the lap-welded joints. The multi-principal powder of FeCoCrNiMn was unable to prevent the formation of Fe-Al intermetallic compounds in the weld metal. However, it did alter the elemental compositions and grain morphologies in the weld metal when compared to the Al-10Si-0.3 Mg powder. Moreover, selecting welding parameters with a low heat input was appropriate for the dissimilar metal joining of aluminum to steel using laser deposition welding. [ABSTRACT FROM AUTHOR]

Analysis of publications has shown that the use of the exothermic addition with a combined oxidizer (xCuO + (x-1)Fe2O3-Al) as components of filler materials will reduce energy consumption and increase the efficiency of the welding/hardfacing process. However, in the literature, there are no studies of exothermic addition with combined oxidizers, which allow to vary the chemical composition of the deposited metal within a wide range. In this paper, the use of exothermic addition with combined oxidizer (xCuO + (x-1)Fe2O3-Al) was considered. To study the characteristics, standard methods were used to determine the arc stability, melting characteristics, weld bead morphology, melting-energy characteristics, and efficiency parameters, and mechanical properties were made. The structural characteristics were analyzed by optical microscope (OM), X-ray diffractometer (XRD). Microhardness values of the hardfaced samples were obtained using a Vickers hardness tester. The greater stability of arc voltage was shown by the processes performed with flux-cored wires in which oxidizing agents of exothermic addition Al-CuO-Fe2O3 in the core filler were taken with an equal content of oxidizing agents or with a slight excess of oxidizing agent CuO/(CuO + Fe2O3) = 0.5–0.6, whereas the greater stability of the welding current was shown by the processes carried out with the use of flux-cored wire with the exothermic addition with an equal or greater proportion of Fe2O3 oxidizer in the combined oxidizer CuO/(CuO + Fe2O3) ≤ 0.5. Further studies of melting characteristics (deposition rate, spattering factor, etc.), melting-energy characteristics (melt-off coefficient CM and deposition rate coefficient Cd), and efficiency showed the efficiency of using exothermic addition with combined oxidizer of Al-CuO-Fe2O3 system. The study showed high arc stability of the hardfacing process, an increase in deposition efficiency (De), and a decrease in spattering loss, which increased deposition rate from 4.73 kg·h−1 to 6.42 kg·h−1 compared to exothermic addition with simple Al-Fe2O3 system. Analysis of weld bead morphology showed improvement in weld bead parameters. The results showed high energy efficiency and productivity of the welding/hardfacing process with the introduction of exothermic addition with combined oxidizer of CuO-Fe2O3-Al system at the following share of copper oxide in combined oxidizer CuO/(CuO + Fe2O3) = 0.5–0.6. [ABSTRACT FROM AUTHOR]

In this study, tungsten–copper (W–Cu) composite was fabricated using the sintering process to examine the corrosion, wear and hardness of the fabricated samples at three different temperatures of 1050, 1150 and 1300 °C. The potentiodynamic polarization behavior of the composite samples was evaluated in 3.5% NaCl solution containing different benzotriazole inhibitors. Finally, the microstructure of the W–Cu composite was examined by SEM, TEM, XRD and EDS analyses. The XRD results on the milled samples showed that the optimal conditions were obtained with a ball to powder ratio of 16:1 and a milling time of 15 h, so that the crystals with a size of 16.76 nm were obtained. Also, the highest hardness (185 HV) and relative density (97.34%) were obtained in the samples sintered at 1300 °C. With increasing the wear force, the work hardening increased in the mechanically mixed layer, which led to a rise in the wear rate and a decrease in the friction coefficient. The corrosion behavior of the composite indicated that by addition of 200 ppm inhibitor in the corrosion solution, the corrosion current density decreased from 3.73 to 0.59 μA/cm2 and the corrosion potential improved from − 630.46 to − 336.28 mVSCE. [ABSTRACT FROM AUTHOR]

Soybean is a source of high-quality vegetable protein and a suitable substitute for meat protein. However, several factors, including a lengthy cooking process, palatability issues, and digestion concerns, have limited their consumption. Several treatments have been suggested to overcome such issues, including infrared heating, which has many advantages over traditional roasting methods. In this study, the three-dimensional microstructure of soybeans with initial moisture contents (12, 16, 20, and 24% w.b.) and treated at different micronization durations (60, 90, and 120 s) at 180 °C were studied and related to quality parameters including water absorption and hardness of both non-cooked and cooked samples. The water absorption tests demonstrated no significant difference (p > 0.05) between the moisture absorbed for 60, 90, and 120 s micronization with initial moisture levels of 12, 16, and 24%. Yet all soybeans treated for 60 s exhibited significantly different results (p < 0.05) compared to raw counterparts. The highest hardness values were achieved after 60 s treatments on 24% moisturized seeds. As expected, the 20 min cooking time resulted in a considerable reduction in soybean hardness. The X-ray micro-computed tomography (micro-CT) was a powerful non-destructive tool to explore the microstructure of individual soybean seeds. Results of X-ray micro-CT have shown an increase in open porosity with increasing infrared treatment time. Overall, the qualitative and quantitative analysis provided in this study may serve as a basis for developing improved food processing techniques. [ABSTRACT FROM AUTHOR]

Experimental results for the long-term full-scale climatic testing of aviation polysulfide and VITEF-1B, VGM-L, VIKSINT U-20-99, and VGF-2M polysiloxane grade sealing materials are presented. The testing have been carried out under open conditions of humid tropical climate characterizing Wanning (Hainan Island, China) and moderately warm climate characterizing Gelendzhik. In order to analyze the reasons for decreasing elasticity and strength, the results of similar testing under the conditions of Moscow, Florida, Arizona, and Vietnam have been used. It is shown that under the influence of radiation, destruction and cross-linking reactions occur that lead to the change in the elasticity of the studied materials. [ABSTRACT FROM AUTHOR]

Friction stir welding was used to join ME20 magnesium alloy. The effect of tool material, pin configuration, spindle speed, and feed rate on the mechanical characteristics and surface finish of the joint was studied with the aid of Taguchi's design of experiments. Statistical analysis of test results and scanning electron microscopic fractography revealed that H13 tool material and a threaded pin configuration led to marked improvements in the properties. An optimum speed of 1600 rpm of the spindle led to favorable weld strength and surface finish. The optimized parametric combination developed through the grey relational approach improved weld strength by 17.78%, joint hardness by 6%, and surface finish by 12.8%. [ABSTRACT FROM AUTHOR]

By means of microstructure observation and mechanical property tests, the influence of the laser pulse energy of the laser shock processing (LSP) on the surface residual stress, microstructure, microhardness and fatigue limits of the M50 steel was studied. Results show that when the laser pulse energy increases from 4, 6 to 8 J, the surface damage of the sample becomes more and more pronounced, which gradually changes from pits to long-strip ravines. LSP increases the hardness of the steel, the maximum hardness occurs on the impact surface, and the microhardness gradually decreases as the distance from the impact surface increases. When the laser pulse energy rises from 4 to 8 J, the maximum hardness of the surface increases from 741 to 845 HV1, which are 2.90 and 11.33% higher than the steel matrix respectively. The depth of the hardened layer of the samples produced by LSP is also deepened when the laser pulse energy increases. The hardened layer depth is approximately 0.3 mm when the laser pulse energy is 4 and 6 J, which reaches 0.5 mm when the laser pulse energy is 8 J. LSP generates residual compressive stresses of − 423, − 565 and − 809 MPa on the surface of the samples when the laser pulse energy are 4, 6 and 8 J respectively. The residual compressive stresses can inhibit the expansion of cracks, so that the steel is less prone to fracture, and thereby the fatigue limit of the steel is increased by 45.95% from 740 MPa of the sample without LSP to 1080 MPa after LSP with the laser pulse energy of 8 J. [ABSTRACT FROM AUTHOR]

Cr-Ni3Al alloy films have been deposited on Si (100) substrate via DC magnetron sputtering. The effect of Cr enrichment on microstructure and mechanical properties has been studied. The evolution of phases, microstructure, surface topography and mechanical properties has been studied using GI-XRD, FE-SEM, AFM and quasi-static nanoindentation, respectively. Results revealed that the alloy films possessed a preferred orientation of (111) plane with a maximum hardness and Young's modulus of ~ 12.7 GPa and ~ 203 GPa for 0 W Cr-Ni3Al films which further decreased to ~ 7 GPa and 129 GPa, respectively, for 40 W Cr-Ni3Al films. The reported values of hardness and Young's modulus are very high in the case of alloy Ni3Al-based coatings when compared with the literature. This study also imitates that with the increase in Cr concentration in the host Ni3Al matrix, the surface roughness increased as a result of the evolution of pores. However, hydrophobicity is observed to be increased with increase in Cr concentration in host Ni3Al coatings with a maximum contact angle of 115.9° for 40 W Cr-Ni3Al alloy film. [ABSTRACT FROM AUTHOR]

This paper investigates a new type of metal matrix composite, namely elemental metal matrix composites (EMMC), where a matrix contains elemental metal powders joined at selective interfaces with other property-enhancing powders to strategically preserve properties of individual constituents. These composites have the potential advantage of reduced demands on high-temperature processing while boasting unique multifunctional properties. cBN-reinforced nickel alloy 20/Cu80 composites (with cBN content ranging from 0 to 5 wt.%) were fabricated using a powder metallurgy processing sequence. The saturation magnetization, the coercivity, electrical resistivity, thermal conductivity, and hardness of the EMMCs were investigated. An increase in cBN content from 1 to 5 wt.% resulted in a slight decline in the relative green and sintered density by about 5% and thermal conductivity from 155.95 to 59.16 W/(m.K) while increasing the electrical resistivity from 4.59 to 12.10 µΩ cm, saturation magnetization from 9.51 to 11.94 emu/g, and hardness from 164 to 206 HV. However, the coercivity decreased from 4 to 2.7 Oe. In accordance with the rule of mixtures and the Maxwell model, an increase in thermal conductivity with an increase in cBN content is predicted. However, using Wiedemann–Franz law (using experimental electrical resistivity measurements) shows a decline in thermal conductivity with increase in cBN content, due to multiple factors related to the sintered EMMCS including porosity, cBN agglomeration, and reduced interfacial bonding between powder constituents. [ABSTRACT FROM AUTHOR]

The microstructural changes in food materials during the baking process directly influence their micromechanical properties and, thus, the strength of the solid walls. Baking time, as one of the vital variables, impacts the microstructural and micromechanical characteristics, alters the texture, and affects customer satisfaction. This research aims to investigate the alteration in three critical micromechanical properties: hardness, stiffness, and Young's modulus, as a function of moisture content during baking of cookies in an oven set at 185 ± 1 °C in the range of 10 to 60-min. The nanoindentation method, which involves pushing a nanoindenter into and removing it from cookie samples to measure the force-displacement data, was employed to measure the micromechanical properties. The results indicated that all the micromechanical properties initially increased when the moisture content decreased from 12.26 to 8.53 g/100 g solids and showed fluctuating trends at the later moisture content values. Throughout the baking process, the moisture content ranges from 2.71 to 12.26 g/100 g solids. Simultaneously, hardness varies from 0.28 to 0.88 GPa, stiffness ranges between 9.77 and 20.16 µN/nm, and Young's modulus experiences minimum and maximum values of 4.34 and 14.55 GPa, respectively. Finally, the Analysis of Variance and Duncan's multiple range tests revealed a significant difference between the mean values of some data points of hardness, stiffness, and Young's modulus as a function of moisture content. [ABSTRACT FROM AUTHOR]

High entropy alloy composites (HEACs) have recently been explored for use in industrial applications. This study investigates the impact of particle size (micro or nano) and content (5 and 10 wt%) of YSZ on the microstructure and tribological properties of AlCoCrFeNi. The samples were prepared using a combination of mechanical alloying and spark plasma sintering. XRD results and Rietveld analysis reveal that HEACs with micro-sized YSZ have a higher BCC/FCC ratio. FESEM and EDS results confirmed the evolution of Al-rich regions in the vicinity of the reinforcements. Especially, in HEA-10NanoYSZ-sample, due to higher interfacial regions, a huge amount of Al-rich phase has been formed which yields the reduction of BCC phase content in this sample. Microhardness and pin-on-disc wear tests show that the samples reinforced with microparticles demonstrate better performance compared to nanocomposite samples. For example, HEA-10MicroYSZ-sample exhibits the highest hardness (5.1 GPa) and the lowest wear characteristics (with a coefficient of friction of 0.8 and a wear rate of 4 × 10−4 mm3/N.m). This can be correlated to the higher hardness and BCC phase content, and grain boundary strengthening in the microcomposites. [ABSTRACT FROM AUTHOR]

The effect of aging treatment on the mechanical properties of 45 vol.% SiCp/6061Al composite fabricated by hot isostatic pressing has been investigated. The results indicate that the hardness and strength of the composite can be strongly improved after solid-solution and aging treatment, with the observations of the accelerated aging kinetic and the double-peak phenomenon. The double-peak phenomenon observed in the 190°C-aged composite is attributed to the substantial amount of G.P. zones and the remarkable precipitation of the β″ and β′ phases, respectively. At 170°C and 180°C, the hardness of the first peak-aged composites were about 216.5 HBW and 217.7 HBW, respectively, and the subsequent fluctuation in hardness was because of the progressive precipitation of the β″ phase and subsequent β′ phase. The maximum yield strength and bending strength were achieved in the composite aged at 170°C for 9 h, being about 688.2 MPa and 798.2 MPa, respectively, with the corresponding increments being about 110.9% and 37% in comparison to that of the as-fabricated composite. [ABSTRACT FROM AUTHOR]

The growth of optically good quality bulk size single crystal of pure and additives added 4-N, N-dimethylamino-4-N-methyl stilbazolium tosylate (DAST) crystal is reported by adopting the conventional slow evaporation solution technique. The grown single crystals were identified by single crystal and power X-ray Diffraction analysis. The luminescence study revealed the transition mechanism of ions. By estimating the hardness, Mayer index, yield strength, elastic stiffness constant, fracture toughness, and brittle index for the grown DAST single crystal using the Vickers micro-hardness analyzer, it is revealed that the grown crystal is a soft material. Using a continuous wave Nd-YAG laser and the standard Z-scan technique, the third-order nonlinearity of the pure and doped DAST single crystal was carefully examined. The third-order nonlinear optical properties show significantly higher values of the nonlinear absorption coefficient (β) and third-order nonlinear susceptibility (χ3). The calculated χ3 of grown pure, EDTA, and DTPA doped DAST crystals are 9.41 × 10−6, 8.06 × 10−6 and 7.92 × 10−6, respectively. The enhanced third-order nonlinear behavior suggests that the title compound is suitable for nonlinear optical applications. [ABSTRACT FROM AUTHOR]

Soft denture liners have limitations like short lifespan and increased microbial buildup. Despite promise as a non-leaching antimicrobial polymer in dentistry, the impact of dimethylaminododecyl methacrylate (DMADDM) on soft liner performance remains unexplored. This study aimed to evaluate the effect of integrating different concentrations of DMADDM to cold cure acrylic resin soft liner, on its antimicrobial activity, cytotoxicity, and physical properties. The same properties were compared to a conventional commercially available denture soft liner. The study employed a control group (conventional soft liner) and three test groups containing 3.3%, 6.6%, and 10% (total mass fraction) DMADDM, respectively. Antimicrobial activity against Candida albicans and Streptococcus mutans was assessed through colony counts and biofilm biomass. Cytotoxicity was evaluated using an oral epithelial cell line. Additionally, wettability and hardness were measured to assess physical properties. Incorporation of DMADDM significantly reduced Candida albicans and Streptococcus mutans counts, and biofilm biomass, compared to the control. Additionally, DMADDM improved the soft liner's wettability and mitigated long-term hardness increase. In conclusion, DMADDM holds promise in enhancing soft liner performance. However, careful selection of its optimum concentration is crucial to ensure both safety and efficacy for future clinical use. [ABSTRACT FROM AUTHOR]

The present experimental study investigates the characteristics of a 1.2 mm thin sheet of Nimonic 80A superalloy. This material has been selected for CO2 laser welding (LBW) view being extensively used in aero-engine components like blades, rings, and discs. Welding parameters of laser power 1400 watts, welding speed 1200 mm/min, and 70 J/mm heat input are considered values for study. All experiments are conducted at ambient temperature. Numerous mechanical tests were executed, including tensile strength and Vickers hardness tests. Tensile results revealed a mean strength of 710 MPa, with yield and ultimate strengths at 881 MPa. Vickers hardness increased gradually from the fusion zone's centerline towards the base metal, with a minimum of 280 HV at the fusion zone's centerline. Metallurgical features were assessed using field emission scanning electron microscopes, optical microscopes, and X-ray diffraction instruments. X-ray diffraction indicated identical phases in the fusion zone, heat-affected zone, and base metal. Scanning electron microscopy was used for cross-sectional analysis of the weld joint. [ABSTRACT FROM AUTHOR]

TiBw mesh reinforced titanium matrix composites were investigated by rotary ultrasonic grinding experiments using a nickel-based electroformed diamond grinding wheel and building a single diamond abrasive grain model and a 2D rotary ultrasonic grinding finite element model. Surface residual stress was obtained by simulation and verified by univariate experiments. Combined with nanoindentation experiments, the changes in residual stress and hardness were acquired. The results show that the reinforced phase fibers will be subjected to high mechanical stress which breaks the fibers and turns them into chips with matrix material. The residual stress of the TiBw-rich region is closer to the actual value due to the high elastic modulus and low residual strain of TiB. Residual compressive stress around −500 MPa exists on the surface of the workpiece under different process parameters. The residual stress decreases remarkably as the spindle speed increases. Meanwhile, the work hardening of workpieces changes similarly to the residual stress. The subsurface microstructure of titanium matrix composites after processing was tested by nanoindentation experiments and backscattered electron diffraction (EBSD). It was found that the surface hardness and dislocation density of the workpiece increased after machining, and the depth of impact was about 10~15 μm. XRD was further used to measure the surface phase of the workpiece under different processing parameters; the results show that the content of TiB reinforcements on the workpiece surface increases and the grain refinement decreases with the increase of spindle speed. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to investigate the microstructural, mechanical, and wear behaviour of AZ31/TiC surface composites fabricated through friction stir processing (FSP). TiC particles are reinforced onto the surface of AZ31 magnesium alloy to enhance its mechanical properties for demanding industrial applications. The FSP technique is employed to achieve a uniform dispersion of TiC particles and grain refinement in the surface composite. Microstructural characterization, mechanical testing (hardness and tensile strength), and wear behaviour evaluation under different operating conditions are performed. Response surface methodology (RSM) is utilized to optimize the wear rate by considering the effects of process parameters. The results reveal a significant improvement in hardness (41.3%) and tensile strength (39.1%) of the FSP-TiC composite compared to the base alloy, attributed to the refined grain structure (6–10 μm) and uniform distribution of TiC particles. The proposed regression model accurately predicts the wear rate, with a confirmation test validating an error percentage within ± 4%. Worn surface analysis elucidates the wear mechanisms, such as shallow grooves, delamination, and oxide layer formation, influenced by the applied load, sliding distance, and sliding velocity. The enhanced mechanical properties and wear resistance are attributed to the synergistic effects of grain refinement, particle-accelerated nucleation, the barrier effect of TiC particles, and improved interfacial bonding achieved through FSP. The optimized FSP-TiC composites exhibit potential for applications in industries demanding high strength, hardness, and wear resistance. [ABSTRACT FROM AUTHOR]

A new class of metal matrix composites known as aluminum hybrid composites has the potential to meet the demands of modern advanced engineering applications. However, their performance was based on the combination and the nature of the reinforcements. The bio-shell waste of snails left over from restaurants and eateries poses a serious environmental threat with little or no economic value. So in this research, an effective utilization of low-cost materials such as aluminum alloy wheel scrap and silicon carbide (SiC) and snail shell particles (SSP) was used to fabricate a hybrid composites. The aluminum matrix composites (AMCs) are prepared with varying weight proportions of SiC particles for 2.5%, 5%, 7.5%, 10%, and 12.5% using vortex casting technique to study the vibration characteristics, hardness, and corrosion behavior of the composites. The vibrational behavior of the composite material is examined by fast Fourier transform (FFT) analysis using the DEWESoft software to obtain the natural frequency of each sample, to compute the damping ratio for each sample, and to obtain the mode shape of the samples. The one which has highest damping ratio is considered to be more resistant to vibration. Hardness is compared using the Brinell hardness. The corrosion tests are conducted under three different environments, namely, marine (3.5% NaCl), industrial (1.5% NaCl), and atmospheric (0.5% NaCl) environments by potentiodynamic polarization technique using the Tafel extrapolation method. Then, the best combination out of the five is selected and the snail shell particles are incorporated into it as an additional reinforcement with the varying weight proportions of 1%, 2%, 3%, and 4%, thereby making it as a hybrid composite. Energy-dispersive spectroscopy (EDS) analysis is carried out to confirm the existence of particulates in the composite material. These samples are again subjected to vibration, hardness, and corrosion tests. The surface morphology of the samples is studied by recording the scanning electron microscopy (SEM) images of the surfaces before and after corrosion. [ABSTRACT FROM AUTHOR]

The wear and corrosion resistance of 316L austenitic stainless steel after strain hardening were studied. 316L austenitic stainless steel was composed of a large amount of austenite and a small fraction of martensite. After strain hardening at room temperature, the contents of phases were not changed basically. With the increase of pre-strain deformation, the microhardness of the surface and cross-section slightly increased, and the microhardness of the sample with pre-strain deformation of 20% was the largest. When the pre-strain deformation was greater than 5%, the surface microhardness was greater than the cross-sectional microhardness. The dynamic average friction coefficients of the stainless steel after pre-strain deformation of 0%, 5%, 10%, and 20% were 0.67, 0.57, 0.2, and 0.12, respectively. The friction coefficient of the samples gradually decreased with the increase of strain hardening. The wear resistance of 316L stainless steel was improved after pre-strain deformation. The steel with pre-strain deformation of 20% had a small abrasive scratch depth and low friction coefficient, which exhibited good wear resistance. The corrosion resistance of the samples after strain hardening deteriorated for the initial state without immersion due to the existence of defects. The corrosion resistance of the sample with pre-strain deformation of 5% after soaking for 3 days was the best, compared with the other as-strained samples. [ABSTRACT FROM AUTHOR]

Al/Mg alloys are extruded at different temperatures to form coated rods by extrusion shear (ES) deformation technology. The deformation behavior of the composite billet during the ES deformation process was analyzed by DEFORM-3DTM finite element simulation (FEM). Analysis of the structure and property of an extruded Al/Mg alloy using a scanning electron microscopy (SEM), microhardness tester and universal mechanical tester. The results show that the symmetrical die structure design of ES deformation can effectively coordinate the forming load, effective stress and temperature field in the deformation process of composite billets. The bimetallic composite rod prepared at 390 °C has a good metallurgical bonding effect with a thickness of approximately 32 μm. The hardness of the bonding layer is higher than that of the aluminum side and the magnesium side, approximately 221 HV, and the shear strength is 13.2 MPa. [ABSTRACT FROM AUTHOR]

In spite of its superior chemical sensitivity, XPS depth profiling is rarely used because of the alteration introduced by the sputter removal process and the resulting inhomogeneous in-depth concentration distribution. Moreover, the application of XPS becomes increasingly challenging in the case of the analysis of thin layers, if the thickness is in the range of 2–3 inelastic mean free paths (IMFP) of the photoelectrons. In this paper we will show that even in these unfavorable cases the XPS depth profiling is applicable. Herein the XPS depth profiling of a model system tungsten-carbide-rich nano-layer of high hardness and corrosion resistance is presented. We will show that the problems arising because of the relatively high IMFP can be corrected by introducing a layer model for the calculation of the observed XPS intensities, while the alteration, e.g. ion mixing, compound formation and similar artefact, introduced by the sputter removal process can be handled by TRIDYN simulation. The method presented here overcomes the limitation of XPS depth profiling. [ABSTRACT FROM AUTHOR]

In order to promote the research on vacuum-arc coating deposition using vaporable TiBSiNi SHS-cathodes, a design of a Zr+ZrxNy+(Zr+TiBSiNi)N+(TiBSiNi)N gradient-layered hardening coating is proposed. Its constituent layers are selected relying on the results of a comparative study of their physical, mechanical and tribotechnical properties. The coating architecture is based on the tribological theory and the analysis of basic requirements to protective-hardening coatings. A comparison of the coating parameters with those of its layers demonstrates that most of them exceed the latter. In particular, its hardness is found to be 40.2 ± 2.0 GPa against that of a ZrN coating equal to 31.5 ± 2.3 GPa and is at the level of the hardest (TiBSiNi)N coating layer (41.9 ± 3.6 GPa). The adhesion (strength of cohesion to substrate) of the gradient-layered coating exceeds those of its constituent layers – ZrN, (TiBSiNi)N, and (Zr+TiBSiNi)N. An annealing treatment of this coating at 700°C in air for 60 min demonstrates its high thermal stability. The proposed gradient-layered coating exhibits a higher hardness (14.8 GPa) compared to the other coating types (5.8–9.1 GPa) after annealing, which, according to the XRD analysis, can be attributed to the availability of zirconium nitrides and harder titanium nitrides in its composition. The principal criteria of the designed gradient-layered coating are its tribo-engineering tests demonstrating both a lower friction coefficient and a higher wear resistance over those of the other coatings. Its wear parameter is found to be 5.4∙10–6 mm3N–1m–1 in coupling with a 100Cr6 steel counterbody compared to that of a conventional ZrN zirconium nitride coating – 43.0∙10–6 mm3N–1m–1. There are also some advantages of the gradient-layered coating revealed in its wear resistance in comparison with the constituent multi-component layers – both with a 100Cr6 steel counterbody and in a tribo-couple with a superhard silicon carbide, SiC. [ABSTRACT FROM AUTHOR]

A new technology has been developed for restoring worn cast iron parts using electric arc surfacing. This technique uniquely combines the simultaneous introduction of filler materials, both as seamless wire and powder alloys, directly into the weld pool. Additionally, oxygen is supplied to the surfacing zone to decarburize the weld pool. The powder alloys used are enriched with graphitizers and carbide-forming elements to protect the melt during the crystallization process. Research has found that the connection zone between the original material and the added layer consistently features a transition layer, regardless of the specific gases and powder materials used. Notably, the use of NPCh‑3 powder, together with the supply of oxygen and carbon dioxide into the weld pool is 2.0–2.7 times thinner than those produced with either PG-12N-01 or PG-10N-04 powders. This method significantly enhances the quality of the deposited layer by increasing the proportion of finely dispersed complex carbides, obtaining an equilibrium structure of fine-plate pearlite with finely dispersed graphite deposits. This results in minimal porosity and the elimination of microcracks, while also reducing cast iron microhardness in the heat-affected zone by 2.1 times. A technology has been developed for restoring cast iron parts through electric arc gas-electric surfacing. This approach has been tested in industrial settings, demonstrating its ability to reduce metal scattering, porosity, and hardness of the deposited layer and the transition zone,. Furthermore, it significantly lowers the likelihood of crack formation, all while minimizing the expenditure on. [ABSTRACT FROM AUTHOR]

This paper investigates the metallurgical factors contributing to the non-conformance in mechanical properties observed in Maraging 250 steel (M250) holding pins after the aging process. Results revealed a significant difference in the mechanical properties between the aged as-received pins and the aged as-annealed rods. Microstructural analysis highlighted the influence of processing conditions, including straightening and centerless grinding, on the material's behavior during aging. Moreover, the presence of retained austenite was found to exceed specified limits in the as-received rods that exhibited mechanical property non-conformance. In this study, a comprehensive metallurgical analysis was conducted to understand the factors contributing to the non-conformance in mechanical properties of aged M250 holding pins and essential steps required for improving the reliability and performance of these components. By gaining insights into the microstructural changes and associated material behavior, appropriate process optimizations and quality control measures can be implemented to ensure the attainment of desired mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, Al2219 composites with varying wt.% of Si3N4 particles using a combination of stir casting and squeeze casting techniques have been explored. Al2219 alloy with 3, 6, and 9 wt.% of Si3N4 composites was examined for the microstructures through SEM analysis, which revealed an even dissemination of the reinforcement particles within the base matrix. Remarkably, did not observe any issues such as particle agglomeration, residual porosity, or other casting-related problems. The inclusion of ceramic particles in the squeezed composites led to significant increments in hardness, tensile and yield strength, and Izod impact strength when compared to the base Al2219 matrix alloy. Notably, during compression testing, observed a considerable increase in compressive strengths, albeit at the expense of reduced failure strain, as the concentration of hard ceramic reinforcement particles increased. [ABSTRACT FROM AUTHOR]

Flexural toppling occurs when a series of layered rock masses bend towards their free face. It is important to evaluate the maximum bending degree and the requirement of supports of flexural toppling rock mass to prevent rock mass cracking and even failure leading to a landslide. Based on the rock tensile strain-softening model, this study proposes a method for calculating the maximum curvature (Cppmax) of flexural toppling rock masses. By applying this method to calculate Cppmax of 9 types of rock masses with different hardness and rock layer thickness, some conclusions are drawn: (1) the internal key factors affecting Cppmax are E⋆ (E⋆= Ess/E0, where E0 and Ess are the mean deformation moduli of the rock before and after reaching its peak tensile strength, respectively), the strain εt corresponding to the tensile strength of rock, and the thickness (h) of rock layers; (2) hard rock layers are more likely to develop into block toppling than soft rock layers; and (3) thin rock layers are more likely to remain in flexural toppling state than thick rock layers. In addition, it is found that Cppmax for flexural toppling rock masses composed of bedded rocks such as gneiss is related to the tensile direction. [ABSTRACT FROM AUTHOR]

We study the computational complexity of (deterministic or randomized) algorithms based on point samples for approximating or integrating functions that can be well approximated by neural networks. Such algorithms (most prominently stochastic gradient descent and its variants) are used extensively in the field of deep learning. One of the most important problems in this field concerns the question of whether it is possible to realize theoretically provable neural network approximation rates by such algorithms. We answer this question in the negative by proving hardness results for the problems of approximation and integration on a novel class of neural network approximation spaces. In particular, our results confirm a conjectured and empirically observed theory-to-practice gap in deep learning. We complement our hardness results by showing that error bounds of a comparable order of convergence are (at least theoretically) achievable. [ABSTRACT FROM AUTHOR]

Depending on the characteristics of soil particles and external load, natural soils often undergo particle breakage which may significantly influence their mechanical behavior. In this study, a hypoplastic model is proposed to describe the sand behavior over a wide range of stress levels, especially those sufficient to cause particle breakage. The characterized void ratios and granulate hardness of the model are related to the plastic work to reflect the impact of particle breakage on the strength and deformation properties of sand. The influence of confining pressure on the extent of particle breakage is properly considered. The model is demonstrated to be capable of simulating the response of crushable sand under various test conditions. The simulation results of the original hypoplastic model are also presented, which indicates that neglecting the particle breakage may cause unreasonable predictions at high stress state. [ABSTRACT FROM AUTHOR]

k-center is one of the most popular clustering models. While it admits a simple 2-approximation in polynomial time in general metrics, the Euclidean version is NP-hard to approximate within a factor of 1.82, even in the plane, if one insists the dependence on k in the running time be polynomial. Without this restriction, a classic algorithm by Agarwal and Procopiuc [Algorithmica 2002] yields an O (n log k) + (1 / ϵ) O (2 d k 1 - 1 / d log k) -time (1 + ϵ) -approximation for Euclidean k-center, where d is the dimension. We show for a closely related problem, k-supplier, the double-exponential dependence on dimension is unavoidable if one hopes to have a sub-linear dependence on k in the exponent. We also derive similar algorithmic results to the ones by Agarwal and Procopiuc for both k-center and k-supplier. We use a relatively new tool, called Voronoi separator, which makes our algorithms and analyses substantially simpler. Furthermore we consider a well-studied generalization of k-center, called Non-uniform k-center (NUkC), where we allow different radii clusters. NUkC is NP-hard to approximate within any factor, even in the Euclidean case. We design a 2 O (k log k) n 2 time 3-approximation for NUkC in general metrics, and a 2 O ((k log k) / ϵ) d n time (1 + ϵ) -approximation for Euclidean NUkC. The latter time bound matches the bound for k-center. [ABSTRACT FROM AUTHOR]

Aluminum alloy forms a protective layer of aluminum oxide when exposed to air, which gives it corrosion resistance. But, the layer can be easily damaged, causing metal corrosion. The hard anodizing method is used to solve this issue. Determining the appropriate anodizing parameters, including current density, process time, and electrolyte concentration, is crucial for attaining the desired thickness and hardness of the anodized layer. An experimental design approach utilizing the response surface method (RSM) was employed to investigate the effects of these variables. Quadratic models were presented to predict the hardness and thickness of the layer with an average error of 2.84% and 3.89%, respectively. The models were verified through analysis of variance (ANOVA) to assess the effect of each parameter and their interactions. Oxalic acid concentration, the interaction between process time and oxalic acid concentration, and the square of current density and process time have a significant impact on hardness. Layer thickness is mainly influenced by current density, process time, and the interaction between process time and oxalic acid concentration. Optimization results show that a current density of 1.19 A / dm 2 , a process time of 160 min, sulfuric and oxalic acid concentrations of 26.25 g r / l i t and 36.88 g r / l i t , respectively, leads to hardness of 434 HV and thickness of 93.6 µm. A scanning electron microscope (SEM) image under optimal conditions shows that aluminum porous arrays created by an anodizing process in mixed sulfuric acid and oxalic acid electrolyte, with a hexagonal shape observed across a wide range of grain domains. [ABSTRACT FROM AUTHOR]

In the present study, the objective is to examine the individual effect of varying the composition and SPS conditions on the final mechanical property (hardness) of alumina–zirconia (AZ) composites through their microstructural variations. To this end, AZ composites with varying zirconia (ZrO2) content are prepared vis-à-vis monolithic alumina (Al2O3) and zirconia (ZrO2) ceramics by spark plasma sintering (SPS). The microstructure evolution, phase formation, and hardness for the monolithic ceramics and AZ composites are systematically investigated and a correlation between them is established using various analytical modeling approaches. By altering the SPS temperature, significant variation in grain sizes were produced for the two monolithic ceramics and various AZ composites. In case of the latter, the size and volume fraction of secondary ZrO2 particles vary according to the composition, i.e., higher the ZrO2 content, coarser and numerous are the second phase particles. The monolithic ceramics exhibit comparatively lower hardness than the AZ composites at equivalent grain sizes. The hardness for the AZ composites and monolithic ceramics also vary marginally with the size of the matrix grains/crystallites. The variation in hardness is rather attributed to the volume fraction of the secondary ZrO2 phase in case of the AZ composites. Altogether, the AZ composite with a finer grain size and low volume fraction of secondary ZrO2 phase exhibits the highest hardness, while coarse-grained microstructure and high ZrO2 content contributes to significantly lower hardness. The present study thus emphasizes the synergistic roles of SPS temperature and composite compositions in dictating their microstructure and mechanical response. [ABSTRACT FROM AUTHOR]

We investigated the effect of steel milling on the structure of SiC–Al2O3 composite materials, synthesized in steel drums using steel milling bodies. The study focused on examining the physical and mechanical properties, specifically the flexural strength and hardness, of the synthesized samples. Optimal values of these characteristics were determined based on the composition of the composite and the specific processing conditions employed. [ABSTRACT FROM AUTHOR]

The influence of the introduction of tungsten carbide nanocrystalline on the microstructure and mechanical characteristics of Ni-WC composite overlays on tool steel was studied. In addition to the improved fraction of retained WC phase and decreased fraction of brittle secondary carbide phases, the influence of the addition of tungsten carbide in nano-size on the microstructure, and mechanical behaviors of the deposited layer was considered. Tungsten carbide nanoparticle in the range 1-7 wt.% was added to existing commercial powder and deposition was carried out. The optimum welding parameters were determined. The results showed that the Ni-WC overlays possessed microstructures including γ-Ni dendrites, with interdendritic Ni-Fe-based eutectics, borides (Fe-Cr)2B, and carbides (Fe, Cr)7C3. With the introduction of WC-nanocrystalline, refining the microstructure was achieved and the dissolution of WC particles enhanced the generation and growth of secondary carbide phases. The strengthening contribution of the reinforcing particles in alloy with 3 wt.% causes an increase in hardness, while the hardness values decrease as the content of WC increases by 7 wt.%. [ABSTRACT FROM AUTHOR]

To obtain a copper alloy with a higher softening temperature, a Cu-Ni-Ti alloy was obtained by the traditional smelting method. And, on this basis, we discuss the effects of atom percentages of different Ni-Ti alloys and the mass percent of Ni + Ti on the properties of single-stage aging of Cu-Ni-Ti alloys at 600°C. The results indicate that the alloy with a Ni/Ti atomic ratio of 2 and a total Ni + Ti content of 3 wt.% exhibits the best performance match. After aging at 600°C for 8 h, the Cu-Ni-Ti alloy's softening temperature exceeded 720°C. This property surpasses that of most age-hardened copper alloys. The corresponding hardness and conductivity were 171 HV and 58% IACS, respectively, which is slightly lower than the commonly used time-reinforced copper alloy. After calculation, the Cu-Ni-Ti alloy with a Ni:Ti atomic ratio of 2 and a total Ni + Ti content of 3 wt.% is referred to as the Cu-2.13Ni-0.87Ti alloy. Transmission electron microscopy observations indicated that the precipitated phase in the aged Cu-2.13Ni-0.87Ti alloy consists of dispersed nanoparticles of Ni3Ti, which have a semi-coherent interface relationship with the matrix. Upon holding the peak-aged Cu-2.13Ni-0.87Ti alloy at different temperatures for 1 h, it was noted that the precipitates exhibited significant coarsening. Furthermore, when the holding temperature surpassed 700°C, the rate of coarsening increased significantly, accompanied by a rapid decline in hardness. [ABSTRACT FROM AUTHOR]

In this work we introduce PERK a compact digital signature scheme based on the hardness of a new variant of the permuted kernel problem (PKP). PERK achieves the smallest signature sizes for any PKP-based scheme for NIST category I security with 6 kB, while obtaining competitive signing and verification timings. PERK also compares well with the general state-of-the-art. To substantiate those claims we provide an optimized constant-time AVX2 implementation, a detailed performance analysis and different size-performance trade-offs. Technically our scheme is based on a Zero-Knowledge Proof of Knowledge following the MPC-in-the-Head paradigm and employing the Fiat–Shamir transform. We provide comprehensive security proofs, ensuring EUF-CMA security for PERK in the random oracle model. The efficiency of PERK greatly stems from our particular choice of PKP variant which allows for an application of the challenge-space amplification technique due to Bidoux–Gaborit (C2SI 2023). Our second main contribution is an in-depth study of the hardness of the introduced problem variant. First, we establish a link between the hardness of our problem variant and the hardness of standard PKP. Then, we initiate an in-depth study of the concrete complexity to solve our variant. We present a novel algorithm which outperforms previous approaches for certain parameter regimes. However, the proximity of our problem variant to the standard variant can be controlled via a specific parameter. This enables us to effectively safeguard against our new attack and potential future extensions by a choice of parameters that ensures only a slight variation from standard PKP. [ABSTRACT FROM AUTHOR]

The effectiveness of high-frequency mechanical impact (HFMI) treatment is studied in this paper considering the reasons of the fatigue life improvement of S335 steel T-welded joints with non-load transverse stiffeners. The main attention is paid to the synergic effects of macroscopic and microscopic residual stresses induced by HFMI post-weld processing as the key factors for superior fatigue life. Macroscopic residual stresses and their distribution nearby (at a distance of 3 mm) and away from (13 mm) the weld toe or the HFMI-produced groove were studied by electronic speckle interferometry and x-ray diffraction (sin2ψ-based method). It was established that HFMI treatment resulted in the transformation of the welding-induced tensile residual stresses (of about yield stress (~ 0.9 σY)) into compressive ones (of ~ 0.9 σY) near the weld toe, while the stresses did not relax away from the HFMI-formed groove. Microscopic residual stresses induced by HFMI were studied as a factor affecting the physical broadening (full width on half maximum—FWHM) of the x-ray diffraction maxima. The correlations of microscopic stresses (lattice micro-strains) with dislocation density, strain-induced dissolution of cementite, and carbon content in the ferrite lattice observed by TEM and the HFMI-induced crystallite refinement with surface hardness are discussed. For various HFMI treatment working speeds employed (1, 5, and 10 mm/s), the hardened layer depths of the S335 steel specimens were in the range of 0.6–1.0 mm. After HFMI, the fatigue strength of the T-welded joint of the S335 steel was observed to be increased by 54% (from 163 to 251 MPa) at 2 × 106 cycles, and fatigue life prolongs by 10 times. [ABSTRACT FROM AUTHOR]

The paper mainly studies the effect of surface carbon content on the deformation of M50 steel bearing ring, and the carbon content is changed by short-time carburizing on the surface of the bearing ring. By using the scanning electron microscope, x-ray diffraction analyzer, hardness tester and torsion spring tester to observe the microstructure and measure the hardness and size variation characteristic. The size and ovality variations of carburized and uncarburized samples are analyzed. Results show that austempering hardness decreases and tempering hardness increases with the increase of surface carbon content. The size of the bearing ring without carburizing is reduced by 0.31 mm after austempering, and the martensite in the surface layer plays a key role in inhibiting the size reduction. The size of the bearing ring with the carbon potential of 0.6% is reduced by 0.01 mm after austempering, and the size reduction is inhibited by the transformation of martensite in the core and surface. The ununiformity of carburizing layer makes the martensitic transition time in different regions inconsistent, resulting in the ovality of M50 steel increased by 0.14 mm. [ABSTRACT FROM AUTHOR]

This work presents the modification of the morphological, structural, chemical composition, mechanical, and tribological properties of the TaN film by the Zr addition on two substrates (Ti6Al4V and Si substrates) using DC magnetron co-sputtering. As a result, the TaN film presented a dense morphology and a structure combination of c-TaN and Ta phases, with a preferential (110) plane of the c-Ta phase. Nevertheless, adding Zr changed from denser to columnar morphology and a preferential (111) plane of the c-TaN phase related to the power applied to the Zr Target (PZr). These modifications caused the reduction of the hardness (H) and elastic modulus (E*) of the films, from values of 25.8 GPa of H and 221.5 GPa of E* for the TaN films to 18 GPa of H and 155.5 GPa for the TaZrN film at PZr = 55 W. In the same way, the failure modes and load capacity properties were modified with the addition of Zr to the TaN matrix, from buckling failure mode with LC1 of 8 N for TaN film to Chevron Tension Cracks failure mode with LC1 of 12.5 N for the TaZrN film at PZr = 45 W. Nevertheless, the wear rate decreased with the addition of Zr to TaN matrix, from 0.25 and 0.15 (m3/mN × 10-12) at 1 and 2 N of load for the surfaces coated with the TaN film to 0.12 and 0.08 (m3/mN × 10-12) at the same loads for the surfaces coated with TaZrN film at PZr = 45 W. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a remarkable green solid-state joining process and it has been proven to be capable of joining advanced materials, such as aluminum matrix composites (AMCs) with sound-quality of joints. As a result, FSW is widely used in many sectors such as aviation, automotive, marine, and structural applications. So far various researchers carried out studies on joint characteristics of FSW and reported better microstructural and mechanical properties. This review study emphasizes various joint characteristics of AMCs namely microhardness, tensile, wear, and microstructural properties of joints obtained by FSW. Also, research work carried out by several researchers in the field of FSW for joining AMCs is summarized. In addition, future trends and challenges in joining of AMCs using FSW is presented. [ABSTRACT FROM AUTHOR]

The main goal of the current work is to develop external excellence, hardness, and anti-corrosion quality materials for engineering and metal finishing applications. To design and prepare a binary type of Zn-Ag nanoparticles as an alloy substantial over on mild steel (MS) engineering substrate using direct current (DC) electrochemical deposition. In this regard, silver nanoparticles are evenly distributed throughout the pure zinc with high-quality surface. Some different bath compositions, experimental settings, and parameters are used to optimize Zn-Ag nanoalloy coatings. The prepared specimen is examined using energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscope (FE-SEM), and X-ray diffraction (XRD). The XRD data for the AgZn3 phase demonstrate well-crystalline properties with reference pattern JCPDS 00–025-1325. Investigations are conducted into electrochemical research, including the Tafel corrosion test and electrochemical impedance spectroscopy (EIS). The results showed AgZn3 and Zn lower values of Icorr (1 × 10−5 A cm−2) compared to the Zn (1 × 10−3) sample, a greater corrosion potential (Ecorr) of − 0.9 V and − 0.6 V, respectively, when deposited on MS substrate. For technical and automotive applications, the produced AgZn3 on MS therefore shows the optimum corrosion resistance and hardness surface with compact microstructure. [ABSTRACT FROM AUTHOR]

One of the major attributes of boiled cassava roots is its ability to soften within a short period, otherwise known as mealiness. This study aimed to establish and validate standard operating procedures for assessing the mealiness of boiled cassava roots. Twenty cassava genotypes, including landrace and improved varieties, were selected for the protocol development, with an additional ten genotypes used for validation. Following cooking, the cassava roots were evaluated for hardness and work done in extrusion using a texturometer equipped with a five-blade Ottawa cell probe. The same samples were assessed for sensory texture analysis using trained panelists for parameters such as softness and chewiness. Pearson's correlation analysis revealed significant positive correlations (p < 0.01) between sensory softness and instrumental texture measurements, as well as between softness and cooking time (p < 0.01, r = 0.94), and between chewiness and cooking time (p < 0.05, r = 0.81). Validation results confirmed significant correlations (p < 0.01) between cooking time, sensory softness, and chewiness. These findings suggest that cooking time can serve as a reliable indicator, closely associated with sensory attributes, in determining the mealiness of boiled cassava roots. This approach offers a practical, mid-throughput method for assessing cassava root mealiness, with implications for breeding improved varieties, farmers adoption, and consumer acceptance. [ABSTRACT FROM AUTHOR]

In this study, the microstructure, mechanical, and tribological properties of (Ti42V28Zr15Nb15)100-xAlx lightweight refractory high-entropy alloys (LRHEAs) were systematically investigated. The results show that the single BCC solid solution structure of LHEAs is maintained after the addition of Al elements, and no other phases are formed. The addition of Al elements to the alloys can be reduce density, improve properties, and enhance wear resistance. While the hardness of the alloy increased from about ~ 352 HV to ~ 430 HV, the tensile ductility decreased significantly. The main reason for the increase in hardness is the strong bonding between aluminum atoms and other atoms. On the other hand, the severe impairment of the tensile properties may be due to the decrease in GNDs. Although the addition of Al helps to reduce the coefficient of friction, the wear rate of the alloy increases. [ABSTRACT FROM AUTHOR]

Password-based authentication is one of the most prevailing access control mechanism. Typical password-authenticated key exchange (PAKE) protocols are single-server settings and are therefore vulnerable to server compromise attack. To defend against such attack, multi-server PAKE schemes have been advanced, but most of which are built on non-quantum-secure hardness assumptions. Lattice-based cryptosystems are regarded as the most promising one for post-quantum eara by NIST, while the known multi-server password-based authentication solution over lattices achieves merely key transport and is public key infrastructure (PKI)-based, resulting in low efficiency and poor deployability. In this work, we resort to distributed smooth projective hash function (SPHF) to bridge the gap between multi-server PAKE protocol and quantum-security. We first design an exact SPHF and derive the first distributed SPHF over lattices by leveraging the additive homomorphic property of the strong learning with errors (LWE) problem. In particular, the relevant parameters of the public key encryption (PKE) scheme it predicates on are identified, thus eliminating the influence of incomplete lattice homomorphism on the correctness of our SPHFs. Pertinent lattice-based multi-server PAKE protocols are further proposed on both transparent and non-transparent transmission modes by integrating our distributed SPHF into the multi-server framework of Raimondo and Gennaro (EUROCRYPT'03). Our PAKE constructions are able to resist both quantum and sever compromise attacks as well as avoid the expensive cryptographic primitives, including non-interactive zero knowledge (NIZK) proofs, signature/verification, secret sharing and fully homomorphic encryption. Experimental results demonstrate that our SPHFs and PAKE protocols offer better efficiency. [ABSTRACT FROM AUTHOR]

In this study, the researchers have attempted to reinforce ZK60 alloys with 5% SiC, 10% SiC, 5% B4C, 10% B4C and 5%SiC + 5%B4C microparticles and investigated the dry wear behavior of these composites. The reinforced composites were produced by the stirred casting method under the atmosphere of SF6. The high-temperature oxidation tendency of Mg and B elements can cause the oxidized-unsuccessful product in the stirred casting process. Therefore, the researchers used the semi-solid temperature stirring method in production as a new solution. The reinforced composites were homogenized at 420 °C for 24 hours and extruded at a rate of 2.25. Following the production process, all samples underwent microstructural characterization analyses, hardness tests, compression tests and dry wear tests. Comparative analysis was done between the results of unreinforced ZK60 alloy and composites from compression and wear tests. This study's results reveal a superior enhancement; the addition of 5% SiC increased the compressive strength of ZK60 alloy by 15%, while the addition of 5% B4C increased by 26%. Furthermore, adding the 5%SiC reinforcement reduced the wear rate by 4.3%, and the 5% B4C reinforcement reduced the wear rate by 11.1%. [ABSTRACT FROM AUTHOR]