Journal of Alloys and Metallurgical Systems最新文献

The various methods of synthesis of iron oxide nanoparticles (IONPs) have been extensively studied in several works of literature. These methods include physical, chemical, and biological nanosynthesis methods with applications in water filtration, environmental remediation, plant improvements, biomedicines, etc. These nanosynthesis approaches revolve around their mode of application, nanomaterial properties, and characterization mechanisms, while little effort has been made to investigate the effect of nanosynthesis parameters based on phase transformation and growth mechanisms of such IONPs. The parameters, which are physical, chemical, mechanical, mineralogical, and morphological, have proven to have tremendous implications on the magnetic behaviors, crystalline size, degree of crystallinity, lattice stain, and mechanical strength of the synthesized IONPs. Thus, this paper gives an overview of the effect of selected nanosynthesis parameters, potential mechanisms of the phase transformation, nanomaterial characterization, and growth mechanism of IONPs produced via the mechanochemical route. The study also suggests future perspectives on the need for further study on the reduction-oxidation process, reaction kinetics, and growth mechanism as influencing factors that can affect the phase structure transformation and alteration of magnetic properties of mechanochemically synthesized IONPs at various levels for suitability in nanotechnology advancement and applications in various fields.

This study focuses on optimizing milling parameters for EN19 steel through the Taguchi method. Utilizing an L9 orthogonal array with three parameters each set at three levels, the study evaluated four quality characteristics in every run. The optimization process involved the use of Signal-to-Noise Ratio (SNR), Analysis of Variance (ANOVA), and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to determine optimal conditions and identify critical parameters influencing surface roughness, temperature, cutting force, and material removal rate.

ANOVA results underscore the significant impact of spindle speed, cutting fluids, and depth of cut (DOC). The TOPSIS analysis identified the optimal conditions as a spindle speed of 710 rpm, a DOC of 0.5 mm, and the use of Neem oil combined with graphene as the cutting fluid. Among these factors, the depth of cut was found to be the most influential, followed by spindle speed and cutting fluid. Confirmation tests corroborated the effectiveness of the optimization approach, affirming its potential to improve milling outcomes. This research offers valuable insights into enhancing machining efficiency and product quality in the milling of EN19 steel.

This study presents a novel cost-effective Fe₃₀Ni₂₅Cr₂₅Mo₁₀Al₁₀ high-entropy alloy with a dual-phase microstructure that was processed using cyclic closed-die forging (CCDF) at room temperature for a maximum of six passes. The as-homogenized alloy exhibited [CrMoFe]-rich dendrites with dual-size morphology dispersed in an almost uniform face-centered cubic (FCC) matrix. It was found that as the number of CCDF passes increased, leading to a more homogenous nanograin, there was an accumulation of dislocations, fragmentation of [CrMoFe]-rich dendrites, and enhanced distribution within the matrix. These conditions were conducive to the creation of a nanostructured Fe₃₀Ni₂₅Cr₂₅Mo₁₀Al₁₀ alloy with superior mechanical properties. Texture analysis indicated that the prominent texture components for the Fe₃₀Ni₂₅Cr₂₅Mo₁₀Al₁₀ alloy after six passes were Rotated Cube {001}<110>, S {123}<634>, and Dillamore {4 4 11}<11 11 8>. After the sixth CCDF pass, the Fe₃₀Ni₂₅Cr₂₅Mo₁₀Al₁₀ alloy exhibited the highest microhardness (∼ 974 HV) and the lowest wear rate (∼ (0.8 ± 0.1) × 10^–5 mm³.N⁻¹.m⁻¹). Additionally, it was proposed that the development of the Rotated Cube {001}<110> texture component contributed positively to enhancing wear resistance in the cost-effective high-entropy alloys. Considering the obtained results, it is reasonable to propose that CCDF processing is significant potential for the advancement of cost-effective nanostructured high-entropy alloys for industrial applications.

This paper offers a comprehensive review and experimental investigation into Zinc-Aluminum (ZA) and Aluminum-Zinc alloys, focusing on their mechanical and tribological properties. Zinc-based alloys like ZA27, ZA12, and ZA8 are esteemed for their superior bearing qualities, with ZA27specifically noted for its strength and widespread use in wear-resistant applications such as plain bearings and bushings. Despite surpassing materials like brass, bronze, and steel bearings, ZA alloys are constrained by their operational temperature limits above 100°C and exhibit lower ductility and impact resistance, potentially leading to dimensional instability. Enhancements via alloying elements (Cu, Mn, Mg, Ni, Si, Ti, Zr, Sr, Sc, Eu, Ag), heat treatment, and increasing aluminum content are identified strategies. The literature indicates that Al-25Zn has mechanical and tribological properties comparable to ZA27, although direct comparative experimental data are scarce. In this experimental investigation, aluminum, zinc, ZA27, and Al-25Zn alloys were fabricated using stir casting, and their properties were examined. Results show that the Al-25Zn alloy possesses the highest hardness, tensile strength, and wear resistance, as well as the lowest coefficient of friction (COF) among the materials tested. The Al-25Zn alloy offers higher elongation and similar thermal constraints, making it ideal for applications needing strong mechanical performance and low friction coefficients.

In the present work, a novel Ti₄₂Nb₄₂Mo₆Fe₅Cr₅ complex concentrated alloy (CCA) was developed using the vacuum arc melting technique. The as-cast CCA underwent a two-stage heat treatment process. In the first stage of heat treatment (HT 1), the alloy was heated to 900˚C. Subsequently, in the second stage of heat treatment (HT 2), the HT 1 samples were annealed at various temperatures, including 700˚C, 900˚C, and 1100˚C, for 20 h. The microstructure and mechanical response of the as-cast, HT 1 and HT 2 (annealed) samples were thoroughly investigated. The phase evolution, microstructure, and chemical composition were analyzed using XRD and SEM-EDS. The XRD analysis revealed major solid solution BCC phases (BCC 1 and BCC 2) with a small amount of Laves phase; however, the amount of Laves phase increased with increase in annealing temperature. The microhardness and elastic modulus of the CCA specimens were evaluated using instrumented micro-indentation. The CCA annealed at 1100˚C exhibits the highest microhardness and elastic modulus, with values of 5.94 ± 0.38 GPa and 124.40 ± 7.17 GPa, respectively. Response surface methodology (RSM) was used to develop a mathematical model aimed at predicting tribological characteristics, specifically the specific wear rate (SWR) and coefficient of friction (COF). RSM proposes a quadratic model to represent the mathematical relationship between input parameters for evaluating SWR and COF. The desirability function approach is employed to optimize input parameters to minimize both SWR and COF. The optimized values of SWR and COF are 6.87 × 10⁻⁴ mm³/N.m and 0.30 under a 27.52 N load, 2.86 Hz oscillation frequency, and 1100˚C annealing temperature. Surface topography analysis of the worn surface was evaluated using SEM and a profilometer to understand the wear mechanism and surface characteristics.

The present study investigates the research conducted on friction stir welding of aluminium alloys AA6061. The experiments were conducted under optimal parametric settings, and the specimens were subsequently subjected to post-processing techniques such as heat treatment and shot peening. The enhancement of weldment strength is contingent upon secondary processing, eliminating internal stress and improving surface qualities. Subsequently, the weldment will undergo mechanical testing and tribometer testing. The conventional testing protocol was implemented to assess the hardness, yield, and tensile strength. The wear and friction test examined the effects of various process factors. The load conditions were set at 10, 30, 50, and 70 N, while the sliding distance was set at 700 m and 1400 m. The experiments were carried out in dry sliding conditions at room temperature and the resulting data were recorded as average values. The welded AA6061 samples exhibited superior hardness and ultimate tensile strength, with the highest average values observed after heat treatment and subsequent shot peening. Attributed to the strengthening effect and achieving an ultra-fine grain size. The results of this inquiry indicate that the yield strength and ultimate tensile strength of the welded sample were significantly increased by heat treatment and shot peening. In particular, when compared to the as-welded AA6061 aluminium alloy sample, the sample's yield and ultimate tensile strength were 39.49 % and 38.7 % greater, respectively. The tribometer test revealed that a rise in load and sliding distance results in an increase in wear rate and a drop in the coefficient of friction. Under a load of 70 N and a sliding distance of 1400 m. s, the heat-treated and shot-peened AA6061 specimen showed a 27.3 % lower wear rate and a 29.6 % lower coefficient of friction compared to the as-welded AA6061 specimen.

Additively manufactured complex geometries from copper alloys with high thermal and mechanical properties have drawn the attention of researchers. The present contribution explores the additive manufacturing (AM) of copper-based alloys from powder particles intended for heat sink and heat exchange applications. Selective laser melting (SLM) parameters featuring low laser beam power (160 W), moderate scanning speed (320 mm/s), and high energy density (200 J/mm³) were employed to fabricate dense components from CuSn10 particles. The present work deal with structural analysis and precision investigation of microfabrication, particularly in Struts, Tubes, and Fins. Mechanical properties (compression and hardness) for Strut structure, differential pressure evaluations for Tube structure, and analyses of thermal and electrical conductivities for Fin structure were investigated. The results showed an improvement in strength compared to those of pure copper, facilitating ease of AM. The obtained results affirm the feasibility of AM, demonstrating the successful creation of complex and combined solid-porous structures using SLM process from Cu alloys. A comprehensive structural investigation and characterization of the Cu–Sn alloy is presented here, aiming to establish a standardized approach for analysing Cu alloys. The results indicate that small-scaled structures fabricated via CuSn10 alloy exhibits a thermal conductivity of 34.3 W·m⁻¹·K⁻¹, an electrical conductivity of 4.72×10⁶ S/m, a hardness of 119 HV-50, a uniform surface roughness of 6 µm, and can withstand a force loading of 1 kN.

This paper presents the results from a recent investigation into the impact of thermal etching and oxidation on grain growth across the surface and bulk of carbon steel during heat treatment. The study used in situ high temperature Scanning Electron Microscopy imaging, facilitated by a novel heat stage, to capture microstructural changes during heat treatments between 800 and 920 °C. The key observations made using this surface imaging included oxidation, the formation and development of thermal etching, and grain boundary movement. In situ data were further supported by ex situ compositional and optical microstructural data obtained by first sectioning the bulk material. Comparison between the results highlighted a significant discrepancy between the surface and bulk grain growth of the specimens during heat treatment at all temperatures. Further investigation concluded that the combination of thermal etching and oxidation lead to the retardation of grain growth on the surface of the carbon steel, but that grain growth in the bulk specimen appeared to be unaffected. The mechanism that causes the grain retardation is not dissimilar to that of Zenner pinning, where in this case oxide particles pin the newly exposed etched grain boundaries. Hence, oxidation formation within the boundaries decreases the energy of the overall system resulting in movement of the grain boundary becoming less energetically favourable. It is anticipated that these findings will be used to improve understanding of the surface effects that occur during the heat treatment of carbon steel in a vacuum environment.

The present study assesses the impact of age hardening parameters, including aging temperature, aging time, and solution time, on the ultimate hardness of heat-treated 2024 aluminum alloys. Using a numerical approach, fuzzy logic systems were utilized as a robust tool to forecast the mechanical characteristics of high copper aluminum solid solutions throughout the age hardening process. In addition, an attempt was made to use a novel simulated annealing technique to determine the optimum hardness and its corresponding process parameters to achieve the highest mechanical properties. Comparing a fuzzy logic model with experimental results obtained from the Brinell hardness test showed the accuracy and confidence of the fuzzy model in representing such properties. The optimization results indicated that the maximum hardness can be obtained with a solution aging temperature of 173.5 °C, an aging time of 19 hours, and a solution time of 58 minutes. Overall, the variation in the experimental peak hardness obtained using the optimized process parameters was the deciding factor in believing the model.

Free-cutting steel, renowned for its exceptional machinability, is susceptible to the impact of manganese sulfide (MnS) and other non-metallic inclusions on the cutting performance and mechanical properties. The composition, morphology, and distribution of these inclusions are influenced by the total oxygen content and doping elements in free-cutting steel. This study focused on three S303 free-cutting steels with different S, Mn, and Cu contents, and the as-received samples were subjected to deoxidation and oxidation remelting, respectively, using a high-vacuum arc melting furnace to control the oxygen content. Thermo-Calc simulations were employed to predict the phases and phase proportions under different processing conditions and to compare with measurements. While the oxygen content was found to subtly affect the distribution and morphology of MnS inclusions, the Mn/S ratio notably affected the size and quantity of MnS inclusions, consequently impacting the mechanical properties of the steel. Higher Cu contents resulted in Cu segregates in the matrix but did not exist in MnS or form CuO; however, it significantly reduced strain hardening. Comparisons between hot-rolled and annealed samples revealed that the most significant changes in mechanical properties resulted from the release of residual stresses. In nanoindentation tests, it was observed that the hardness of MnS inclusion was influenced mainly by residual stresses not doping elements.