Journal of Materials Engineering and Performance最新文献

The aim is to investigate the cutting machining mechanism of FeCoCrNiAl high-entropy alloy after severe plastic deformation enhancement. The effects of factors such as rolling reduction on the cutting temperature, cutting force, and residual stress of FeCoCrNiAl high-entropy alloy were analyzed using the finite element method, and related verifications were conducted through experiments. The results indicate that an increase in cutting speed and cutting depth leads to a rise in cutting temperature, while an increase in reduction amount results in a decrease in cutting temperature. When the reduction amount is 1 mm, an increase in cutting depth from 0.5 to 1 mm leads to an approximately 192 °C increase in temperature; the increase in cutting speed and cutting depth causes the cutting force to rise, with the cutting depth having a more significant impact on the cutting force. With a rolling reduction of 3 mm and an increase in cutting depth from 0.5 to 1 mm, the cutting force approximately doubles, and there is a negative correlation between cutting force and reduction amount. The residual compressive stress on the processed surface shows a significant negative correlation with cutting speed, while there is a significant positive correlation between cutting depth and residual compressive stress; the influence of rolling reduction on the residual compressive stress of the machined workpiece is mainly reflected in the depth of the residual stress layer.

This study investigates the influence of various heat treatment processes on the dynamic impact properties of 7075 aluminum alloy. Dynamic compression tests were performed using a Hopkinson pressure bar over a temperature range of 20 °C to 420 °C and strain rates from 1800 to 5800 s⁻¹, followed by an analysis of the alloy’s mechanical behavior under these conditions. The findings show that the yield strength of 7075 aluminum alloy, after undergoing three distinct heat treatment procedures, increases with higher strain rates and decreases as temperature rises, indicating a clear sensitivity to both factors. At ambient temperature, the flow stress of the alloy demonstrates an upward trend across all three heat treatments as the strain rate increases. Specifically, the yield strengths in the T6, T76, and RRA conditions at a strain rate of 5800 s⁻¹ are 1.47, 1.38, and 1.19 times greater than those measured at 1800 s⁻¹, respectively. As the temperature elevates to 420 °C, all three aging conditions reveal pronounced thermal softening, attributed to high-temperature deformation. At elevated strain rates under room temperature conditions, the yield strength follows the order of T76 > T6 > RRA. However, at 420 °C, with the same high strain rates, the order shifts to RRA > T76 > T6.

Recently, researchers have progressively focused on the corrosion of biomedical implants and the leaching of metal ions into body fluids. To enhance the corrosion and wear resistance of metal implants, Titanium Nitride (TiN) coatings have been suggested as a viable option due to their high hardness and corrosion resistance. In the present study, TiN was formed on a Ti-6Al-4V alloy using the hollow cathode plasma nitriding process in N₂-H₂ gaseous mixture at 800 °C for 8 h. The microstructural and structural properties of the TiN layer were characterized by scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. To study the corrosion behavior of this alloy, potentiodynamic polarization and electrochemical impedance measurements were conducted in three different simulated solutions (3.5wt.% NaCl, Hank’s solution and artificial saliva). Electrochemical studies revealed that the plasma nitrided Ti-6Al-4V alloy exhibited superior corrosion resistance properties compared to the pristine Ti-6Al-4V alloy in all three simulated solutions. However, the corrosion resistance of both untreated Ti-6Al-4V and plasma nitrided Ti-6Al-4V alloy was found to be lower in artificial saliva solution compared to the other solutions. Additionally, the plasma nitrided Ti-6Al-4V alloy showed reduced metal ion release in the simulated solutions. Based on these findings, it can be concluded that the plasma nitrided Ti-6Al-4V alloy holds a great potential as an implant material in the medical field.

In this study, the effects of heat treatment on the mechanical and corrosion performance of Cu-P-Ag alloys were systematically investigated with the aim of achieving an optimized balance between flexibility, mechanical strength, and electrochemical stability. Cu-P-Ag alloys are widely used in industrial brazing and electronic applications due to their high electrical conductivity, thermal performance, and corrosion resistance. However, improving mechanical strength often compromises flexibility and increases residual stress causing early fractures during production. To address this challenge, the alloy was subjected to controlled heat treatments at various temperatures (100 to 550 °C). Microstructural evolution was analyzed via SEM and XRD, while hardness and residual stress measurements provided insights into mechanical behavior. The results reveal that heat treatment at 400 °C significantly enhances flexibility and reduces internal stress, primarily due to the uniform and fine precipitation of β-Ag phases and the formation of a uniform and thermodynamically stable microstructure. In parallel, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and Mott–Schottky analysis were employed to assess corrosion resistance in 0.9% NaCl solution. The findings indicate that the passive films formed post-treatment at 400 °C exhibit superior protective characteristics, attributed to improved film compactness and reduced surface heterogeneity. This optimized heat treatment condition successfully enhances both mechanical and electrochemical performance, making the Cu-P-Ag alloy more suitable for high-performance industrial applications where strength, softness, and corrosion resistance need to be balanced.

Glass samples of CuO/Fe₂O₃ reinforced bismuth borate containing ZnO and NaF with the chemical form 65B₂O₃-15NaF-15ZnO- 5Bi₂O₃-XFe₂O₃- YCuO: (X,Y) = (0.0,0.0) {S0}, (0.1, 0.4) {S1}, (0.2, 0.3) {S2}, (0.3, 0.2) {S3}, (0.4, 0.1) {S4}, and (0.5, 0.0) {S5} mol.% were prepared via melt quenching procedure. The influence of CuO/Fe₂O₃ on the structure, physical properties, and γ-ray attenuation capability was examined. The non-crystallinity nature of samples was confirmed by XRD measurements and SEM images. The density (D_s) of samples increased from 3.10 to 3.30 g/cm³ as Fe₂O₃concentration increase from 0.0 to 0.5 mol.%. The molar volume (V_m) declined from 28.05 to 26.62 cm³/mol. The parameter of oxygen packing density (OPD) enhanced from 80.20 to 85.09. The oxygen molar volume (OMV) changed as 12.47 cm³/mol for S0 sample and 11.75 cm³/mol for S5 sample. Direct (E_opt-direct) and indirect (E_opt-indirect) optical band gaps decreased with doping with Fe⁺³ and Cu²⁺ ions in the glass networks. E_opt-direct decreased from 3.685 to 3.620 eV, while E_opt-indirect varied between 3.642 and 3.595 eV. Undoped sample S0 exhibited a broad strong UV absorption which related to unavoidable trace ferric ions, Fe³⁺ ions, impurities contaminated within the raw materials used for the preparation of the glasses. For doped glasses UV-visible bands due to doping with 3d transition metal ions. In terms of γ-ray shielding, linear (LAC) absorption coefficient followed the order: S0_LAC < S1_LAC < S2_LAC < S3_LAC < S4_LAC < S5_LAC. The S5 glass sample has the lowest half value layer (HVL) and mean free path (MFP). The effective atomic number (({text{Z}}_{text{eff}})) has the same trend of MAC. The suggested S5 sample presents the best γ-ray shielding capability among the investigated samples. Results confirm that the sample coded as S5 is superior as γ-ray shields compared to ordinary concrete (OC) and RS-253-G18 glasses.

Due to the regulations restricting the use of lead, the implementation of lead-free solders became a legal requirement more than 15 years ago. In addition to the well-known SAC305 solder, new alloys containing various concentrations of Bi, together with other additives improving the soldering process and reliability of joints, have appeared. The paper focuses on comparative study of wetting properties of SAC305 and commercially available third-generation lead-free solder alloys containing Bi: REL61, REL22, and HRL-1. The improved sessile drop method, was applied to measure the contact angle (θ) of the selected solders on a copper substrate. The highest contact angle value (36°) was observe for HRL-1 and the lowest (27°) for REL22. Initially the spreading phenomenon was very fast, below the resolution of the measurement method. In some cases of the wetting disturbance by the external factors, wetting has been inhibited and the intermetallic phases developed at the solder/substrate. The formation of a halo area at the substrate around the drop was also observed, most likely formed due to the surface diffusion of solder atoms. This phenomenon led to a further reduction of the contact angle, but the spreading of the drop was much slower. Comprehensive microstructure and chemical composition examination of the drop/substrate interfaces after wetting tests evidenced the presence of Cu₆Sn₅ phase for all samples. Moreover, it was proved that the alloy additives (e.g., Ag and Bi) influenced the achieved contact angle and reduced unfavorable intermetallic phases formation such as Cu₃Sn (e.g., Ni, Sb, and Ti).

Wear and corrosion are the main causes of structural failure of mechanical parts, using thermal spraying to fabricate raw materials into coating, which is a common method of protection of mechanical parts. In this work, FeCrCoMoCB amorphous coating was fabricated on the 45# steel substrate using supersonic plasma spraying (SPS). The microstructure, phase composition, mechanical, corrosion, and wear properties of FeCrCoMoCB amorphous coating were systematically investigated. The results show that FeCrCoMoCB amorphous coating had a relatively flat surface, low porosity with a dense structure, high hardness, and had an amorphous rate of more than 90%. The coating displays a passive region of about 500 mV, corrosion potential of − 1.01 V, and current density of 1.89 × 10^-5 A/cm². The wear mechanism of FeCrCoMoCB amorphous coating is dominated by oxidation wear, and with the increase of load, the abrasive wear transforms into delamination wear.

The present research investigates the performance of mild steel (MS), copper (Cu), and tungsten copper (WCu) form tools in fabricating large-area micro-textured surfaces, alongside the optimization of EDM parameters for surface texturing. The WCu tool electrode achieved the highest form accuracy, producing uniform, sharp-edged micro-pillars, followed by Cu and MS electrodes. The lower form accuracy of the MS tool leads to a higher overcut in the MS-textured surface and reduced interspacing, resulting in increased textured density. The overcut in the cavities is (sim) 50 ± 15, (sim) 75 ± 20, and (sim) 110 ± 20 µm for WCu, Cu, and MS tools, respectively. MS-textured surfaces exhibited the roughest morphology, with uneven recast material deposition with high frequency, micro-cracks, pockmarks, and voids, further reducing the patterned surfaces' hydrophobicity. XRD analysis indicates tensile residual stress, microstrain, crystallite size reduction, stable oxide layer, and carbide formation on patterned surfaces. The MS-textured surface exhibited the highest corrosion resistance, with a corrosion rate (CR) of 0.00918 mm/year, compared to the Cu- and WCu-textured surfaces, which showed CR values of 0.01994 and 0.02773 mm/year, respectively. Additionally, the MS-textured surface demonstrated the lowest wear rate and coefficient of friction (COF), recording a wear rate of 0.001138 mm³/m and a COF of 0.433.