Journal of Alloys and Metallurgical Systems最新文献

This study aimed to synthesize lightweight steels in situ reinforced with 5 % and 10 vol% of TiB₂ and evaluate the microstructural, physical, and mechanical properties. The Fe-(15;20 wt%)Mn-3 wt%Al-0.1 wt%C with 5 and 10 vol% of TiB₂ were produced by spray forming followed by hot rolling and annealing. The concept of varying the manganese content was to assess the influence of the matrix constitution on the composite properties. The findings pointed to a direct correlation between the manganese content and the size and morphology of the TiB₂ particles. The presence of the ceramic particles re-established the modulus of elasticity above 200 GPa only for composites with a predominantly ferritic matrix. The composites with a matrix composed mostly of austenite showed no gains in ductility during the tensile tests despite the activation of the TWIP effect. However, their wear behavior stands out positively.

This study reports the effects of Cr addition on the microstructure, superelasticity and corrosion resistance improvement of CuAlBe shape memory alloy. Analysis via structural, morphological, thermal, mechanical and electrochemical characterizations were performed. The analyses revealed austenite as the stable phase at room temperature for all samples. The increase in the Cr content caused a slight increase in the recovery rate and dissipated energy. Electrochemical results demonstrate that a small addition of Cr (0.1–0.3 wt%) increase the corrosion resistance due the decreases of the corrosion current density and increase of the corrosion potential.

The use of medium and low-grade iron ore is gradually becoming more important due to the depletion of high-grade iron ore reserves and stringent environmental acts/rules. Slimes from iron ore washing were discarded in tailing dams; however, there is currently consideration for recovering iron values from ultra-fines as well. There are enormous fine dumps that are still unutilised. Hence, this study attempt to delve the optimization of iron ore slimes an indeed requirement for manufacturing and design in industries. Leveraging a flocculation process, coupled with the implementation of an Artificial Neural Network (ANN) predictive model, the Kiriburu processing plant serves as the primary source for iron ore slime samples. Chemical analyses of the collected iron samples reveal a composition featuring 58.24 % iron content, 3.47 % Al₂O₃, 4.72 % SiO₂, and 5.18 % LOI (Loss on Ignition). The investigation explores the performance of the flocculation technique under varying pH levels, different pulp densities, and diverse flocculant dosages. Furthermore, the varying parameters selected are pH from 6 to 11, pulp density from 1 % to 15 %, and flocculant dose from 0.03 to 0.27 mg/g. The study's findings showcase a substantial improvement in the Fe grade of iron ore, escalating from 58.24 % to 66.12 %, with an impressive recovery rate of 82.54 % achieved using a flocculant dosage of 0.09 mg/g at pH 10. Additionally, a performance assessment of the selective flocculation method for iron ore slimes is conducted using an ANN predictive model, with recovery as the pivotal parameter. The input parameters for this model encompass pH, pulp density, and flocculant dosages. Employing a three-layer ANN model with a 3–3–1 architecture and utilizing feed-forward back propagation, the study demonstrates a close alignment between predicted values and experimental data, confirming the model's effectiveness for practical manufacturing applications. Information regarding the potential applications of the model's iron ore slime beneficiation efficacy for the manufacturing sector should be considered. This could entail lower waste, more effectiveness, or cost savings. Emphasise any possible ramifications for sustainability or the environment that would make the study pertinent in a larger perspective.

In this paper, the microstructure, and mechanical properties of Ti-6Al-4V fabricated through Laser Directed Energy Deposition (L-DED) process are investigated and discussed. Deposited coupons were produced on Ti-6Al-4V wrought substrate using Ti-6Al-4V ELI grade wire with the laser wire deposition (LWD) process. Characterization efforts led to the evaluation of the microstructure, hardness, tensile behavior, and fatigue crack growth resistance of the build-up alloy. Microstructure of the deposit consists of columnar prior β grains and basket-weave α/β phase mixture. The size of the alpha laths is measured as 1.2 ± 0.3 µm and 0.8 ± 0.2 µm in the banded zone and band-free zone, respectively. Hardness of the deposited block is found to be uniform and ranging between 321 and 323 H_v. Tensile and fatigue crack growth properties of the deposited block were evaluated in various orientations. Tensile specimens loaded in the deposition direction exhibited 824 MPa and 930 MPa for yield and ultimate tensile strength, respectively. Tensile specimens loaded in the build direction exhibited 782 MPa and 907 MPa for yield and ultimate tensile strength, respectively. The analysis reveal that the tensile properties of the deposited material match the strength requirements for ASTM F1108 Cast Ti-6Al-4V. However, they fell just below the AMS 4911P Wrought Ti-6Al-4V standard. Fatigue Crack Growth Rate tests were conducted for three directions: parallel to the deposition direction, parallel to the build direction and at 45° of the deposition direction. No significant differences in crack growth properties were observed between the different orientations with average crack initiation near threshold (ΔK_th) and the fracture toughness (K_c) value of 3.6 MPa√m and 69 MPa√m, respectively. The crack propagation properties are similar to cast & wrought materials.

FSW joints are promising because they have a minimal heat input in welding and can limit the amount of intermetallic compound formation in dissimilar metals. Solid-state welding processes, particularly friction stir welding (FSW), are preferred for welding aluminium alloys due to their low heat input and ability to minimize intermetallic compound formation. This study conducted FSW trials on AA7075 and AA2024 alloys, each 4 mm thick. Parameters such as axial force, rotational speed, and traverse feed were adjusted while keeping other factors constant. The study analyzed weld geometry characteristics, including bead width and penetration depth. Angle distortions during FSW of thin plates in a butt joint were investigated. Additionally, the study examined the effects of FSW parameters on mechanical properties such as tensile strength and hardness immediately after welding. Microstructures of the welds were observed using optical microscopy (OM). The optimal mechanical properties are achieved at a rotational speed of 1000 rpm, a traverse feed of 30 mm/min, and an axial force of 10 kN. This optimal condition facilitates material flow around the pin at an ideal speed, ensuring adequate material filling and preventing tunnel formation. The stir zone's microstructure under these parameters exhibits a finely recrystallized structure with a significantly smaller grain size than the base material. Consequently, this enhances the joint's microhardness and tensile strength.

The current experimental work uses die casting, a liquid processing method, to create functionally graded material (FGM). To reduce the production of undesired intermetallic compounds, the FGM samples were created both with and without interfacing foil during the procedure. Mechanical properties including impact strength and microhardness were examined throughout the manufactured sample's cross-section. In addition, the interfacial bonding of FGM samples with and without an interacting foil was determined by estimating the shear strength. Analysis of the samples using X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveals the existence of compounds in the sample as well as the diffusion of Al and Zn particles from one side to the other. Compared to the FGM without foil, it is observed that the diffusion rate at the interface is regulated when the foil is present. In addition, it was found that, in contrast to pb foil, the inclusion of Ag foil limited the rate at which particles could move from one side to the other. Additionally, machining investigations are carried out at varying depths on both sides of the sample in the direction of the interface with the assistance of electric discharge machining.

This study aims to predict the various phases present in high entropy alloys (HEAs) and consequently classify their crystal structure employing multiple machine learning (ML) algorithms utilizing five thermodynamic, electronic and configurational parameters which are considered to be essential for the formation of HEA phases. The properties of a high entropy alloy can eventually be traced through accurate phase and crystal structure prediction, which is essential for selecting the ideal elements for designs. Twelve distinct ML algorithms were executed to predict the phases of HEAs, adopting an experimental database of 322 different HEAs, involving 33 amorphous (AM), 31 intermetallics (IM), and 258 solid solutions (SS) phases. Among the twelve ML models, Cat Boost Classifier displayed the optimum accuracy of 98.06 % for phase predictions. Further, crystal structure classification of the SS phase (body-centered cubic- BCC, face-centered cubic- FCC, and mixed body-centered and face-centered cubic- BCC+FCC) has endeavoured for better microstructure evolution using a different database containing of 194 additional HEAs data with 61 FCC, 76 BCC, and 57 BCC+FCC crystal structures and in comparison to the other models tested, the Gradient Boosting Classifier evolved with the highest accuracy of 86.90 %. An ensemble classifier was also introduced to improve the performance of the ML models, resulting in an accuracy increase to 98.70 % and 86.95 % for phase and crystal structure predictions, respectively. Additionally, the influence of parameters on model accuracy was determined independently.

To achieve a superior-quality weld, it is imperative to employ the appropriate welding parameters. In this study, the Taguchi-based technique for order of preference by similarity to ideal solution (TOPSIS) method has been used to improve the welding parameters such as current, voltage, and travel speed for metal inert gas (MIG) welding on the AA6063 aluminum alloy. Experiments have been performed to assess the hardness and strength characteristics of the joints. The assignment of the specimen was determined by the TOPSIS algorithm, which considers the specimen's performance score. The analysis of variance (ANOVA) approach was performed to identify the parameter with the highest significance level. A mathematical model has been established using a regression equation to establish a relationship between performance scores' signal-to-noise (S/N) ratio and process parameters. The optimal parameters for the butt joint welded using the MIG technique were determined to be a current of 120 A, a voltage of 20 V, and a travel speed of 3 cm/min. The ANOVA findings reveal that the current factor exhibits the highest level of statistical significance, accounting for 63 % of the observed variation. This was followed by voltage and travel speed, which contributed 24 % and 10.3 %, respectively. To ensure the validity of the findings, a confirmatory experiment was conducted using parameters optimized for analysis. The results of the confirmation indicate a strong alignment with the approach that was implemented.

The hot deformation behavior of Al-Zn/martensitic stainless steel particles-based composite (Al-Zn/6 %SSp), was examined in this study. The composite was tested using isothermal compression at 200–350 °C/0.01–10 s⁻¹ and a global strain of 0.5. From the results, it was noticed that the composite’s flow stress increased with strain rate increase and drop in temperature. The constitutive equation from the hot-worked composites resulted in an estimated activation energy of 226.27 kJ/mol, which was 58 % more than that for the self-diffusion of aluminum alloy (142 kJ/mol). These findings suggest dynamic recrystallization (DRX) as the dominant deformation mechanism, as confirmed from the microstructures of the hot worked samples mostly at high temperatures and strain rates. Work hardening was predicted to dominate the deformation process by the stress exponent (n) value of 10.36 (which exceeded 5), but this was inconsistent with the microstructural observations. Comparing the linear fitting of calculated flow stress data with the estimated flow stress yielded a correlation coefficient (R²) of approximately 0.97. This observation demonstrates an effective relationship involving the calculated stress with the computed stress value for the composite material that was fabricated. Based on the processing map analysis, the instability regime occurs at 200270 °C/0.01–10 s⁻¹. The stable domain established was at 280–340^◦C/0.01–10 s⁻¹ which is most suitable for achieving the best microstructural conditions for enhanced service performance.

The microstructure and grain refinement of Al-4.5Er-1Zr-1.5Ti master alloy were analyzed by the refinement experiment, OM, SEM and XRD. The results show that the grain size of pure aluminum is reduced from 14,000μm to 202μm by Al-4.5Er-1Zr-1.5Ti master alloy, which is mainly due to the nucleation promoted by Ti₂Al₂₀Er, Al₃Er and Al₃Ti. Plastic deformation further improves the refining effect of the material by improving the primary phase size, and the Al-4.5Er-1Zr-1.5Ti −2ARB can refine the pure aluminum from 202 mμm to 150μm, and the refinement was increased by 25.7 %. The master alloy showed a better refinement effect in Al-5Cu alloy than pure aluminum, with a grain size of 92μm and a refinement improvement of 97.8 %.