Recent advances in the manufacturing business have necessitated accelerated delivery of high entropy alloys (HEAs) for consumer markets because of an excellent combination of thermal, chemical, and mechanical properties. In the HEA manufacturing process, the additive manufacturing (AM) using selective laser melting (SLM) technique is widely adopted because it offers high-quality, cost-effective, and reliable HEA parts. HEAs possess unique phase constitutions and exhibit some distinctive characteristics such as high entropy, sluggish diffusion, cocktail, and lattice distortion effects for applications in the key sectors of energy, aerospace, transportation, and biomedical engineering. However, a major challenge with SLM manufacturing of HEAs arises from defects such as porosity, cracking, and delamination from the build plate which hampers the mechanical and structural integrity of HEA parts. Given the limited research on the microstructural evolution of AM-SLM manufactured alloy, this review examines the current state of knowledge from diverse perspectives including the effect of SLM processing parameters such as the powder characteristics, the laser characteristics, layer thickness on the microstructure, and density of the produced HEAs. The review also highlights the microstructural features and defects formation on the mechanical, thermal, corrosion, irridation, and creep properties. Furthermore, the microstructural defect mitigating approaches were discussed. The final section of this review summarizes the key findings offering sustainable solutions across various industries and future research directions for SLM-HEA advancement.

The paper investigates how the Cr/C ratio influences microstructure and corrosion behaviour of hypoeutectic high-chromium cast irons (HCCIs) in 3.5 wt% NaCl, 0.5 M NaOH and 0.5 M H2SO4. Three alloys; P1 (Cr/C = 12.13, 26.3% carbides), P2 (8.62, 37.3%) and P3 (8.06, 42.9%) were evaluated based on carbide size, morphology and distribution. Open-circuit potential and potentiodynamic polarisation corrosion tests were performed on the samples. In NaCl, P3 showed the most severe corrosion due to micro-galvanic effects from coarse, interconnected carbides and limited Cr available for passivation. In NaOH, P1 corroded the most due to rapid carbide dissolution and insufficient sustained Cr release for passive film growth. In H2SO4, P3 suffered the greatest attack, driven by galvanic interactions and unstable film formation. Heat treatment refined carbide distribution and promoted secondary carbide precipitation. These changes improved corrosion resistance in neutral media but increased it in acidic and alkaline. These results show that Cr/C ratio and carbide control are key to optimising HCCI corrosion resistance.

Utilizing ether-based electrolytes presents a viable approach for addressing the enduring challenges linked to lithium-metal batteries (LMBs), especially concerning solid-electrolyte interphase (SEI) stabilization and enhancement. By employing a comprehensive methodology involving detailed analysis of SEI formation kinetics, strategic modifications to the anode, and customized electrolyte compositions, we can unlock improved stability, ionic conductivity, and overall superior performance of LMBs. Using in-situ characterization methodologies such as x-ray photoelectron spectroscopy (XPS) is critical for comprehending the complex interplay between electrolyte composition, SEI characteristics, and their consequent effects on the behavior of the full cell. The investigation into innovative surface pre-treatments and electrolyte additives, along with a thorough assessment of their interactions, facilitates the systematic design of SEI layers that enable efficient and reversible lithium cycling. Additionally, thoroughly examining ether-based electrolytes in full-cell configurations, incorporating varied cathode materials and operational parameters is imperative for confirming their long-term cycling stability, safety, efficient charge/discharge processes, and compatibility with high-voltage systems. By amalgamating these research avenues, substantial progress is envisaged in the advancement of next-generation lithium-metal batteries characterized by high energy density, prolonged lifespan, and enhanced safety, thus paving the way for their widespread integration in a myriad of applications spanning from portable electronics to electric automobiles and high charging/discharging energy storage systems. The ongoing exploration of ether-based electrolytes, in conjunction with innovative SEI engineering tactics, signifies a critical stride towards realizing the full potential of this promising energy storage technology.

The study was conducted to determine the optimised sintering conditions for producing low-density stainless steel via powder metallurgy route. Low-density Fe–Mn–Al–Cr–C stainless-steel alloys containing Mo and Cu were produced from commercially available elemental powders via mechanical alloying followed by consolidation using spark plasma sintering (SPS). Four alloy compositions under varying sintering parameters, including temperature (900°C–1100°C), dwell time (5–7 min) and pressure (40–50 MPa), were explored. Electrochemical testing, including open-circuit potential (OCP) and cyclic polarisation (CP), was performed in 0.9% NaCl to evaluate corrosion susceptibility. Characterisation of both the mechanically alloyed powders and the sintered alloys was performed using scanning electron microscopy–backscattered electron imaging, scanning electron microscopy–energy-dispersive X-ray spectroscopy and X-ray diffraction. The XRD patterns of the mechanically alloyed powders revealed the presence of two phases, austenite and ferrite, together with the formation of Mo-enriched precipitates. Results indicated that sintering temperature, pressure and dwell time had a significant effect on the final density, which increased with higher parameter values. The sintered alloys achieved relative densities between approximately 94% and 100%. The porosity ranged from 0.01% to 5%. Microstructural examination indicated that the alloys consist mainly of a duplex configuration made up of γ-austenite with an FCC crystal structure and α-ferrite with a BCC structure. In addition, precipitates enriched in Cr and Mo were identified particularly in Alloys 3 (Fe–30.67Mn–2.39Al–4.23Cr–0.09C–5.20Mo–3.44Cu wt%) and 4 (Fe–21.55Mn–3.78Al–4.12Cr–0.22C–5.30Mo–3.51Cu wt%). Among all compositions, Alloy 1 (6Fe-31.49 Mn-2.45 Al-4.34 Cr-0.09 C wt%) demonstrated the best overall sintering response, microstructural quality and corrosion resistance, achieving a high density of 99.4% (Alloy 1C) and a low corrosion rate of 0.087 mm/yr (Alloy 1D). The optimum sintering conditions were determined to be 1100°C and 50 MPa for Alloys 1 (Fe-31.49Mn-2.45Al-4.34Cr-0.09C wt%) and 2 (Fe-22.14Mn-3.88Al-4.23Cr-0.23C wt%) and 900°C and 50 MPa for Alloys 3 (Fe-30.67Mn-2.39Al-4.23Cr-0.09C-5.20Mo-3.44Cu wt%) and 4 (Fe-21.55Mn-3.78Al-4.12Cr-0.22C-5.30Mo-3.51Cu wt%).

Incorporating TiAl alloys in engine applications offers benefits including reduced fuel consumption and improved efficiency. However, understanding the wear behaviour of these materials is an important consideration due to their use in harsh environments involving movable parts. This study investigated the wear behaviour and mechanisms of Ti–48Al–2Nb–0.3Si-1Sn (TiAl–S1) together with Ti–48Al–2Nb–0.3Si (TiAl–S0) as a reference alloy against an alumina ball. Scanning electron microscopy (SEM) analysis showed that the addition of Sn refined the lamellar structure from 216 μm to 130 μm and promoted more uniform deformation. SEM observations also indicated that abrasive wear is the dominant mechanism in the TiAl alloys. The TiAl–S1 exhibited lower hardness, resulting in deformation of wear debris and promoting third body acting as a lubricant. SEM-EDS revealed that the tribo-layer and wear debris originated from the TiAl materials rather than the counterpart alumina material. Both alloys demonstrated noble wear resistance, with a wear rate of 7.542 × 10−6 mm3/Nm for TiAl–S1 and 6.729 × 10−6 mm3/Nm for TiAl–S0. Even though both TiAl alloys experienced abrasive wear mechanisms, the addition of Sn emerges as a promising alloying strategy, for enhancing ductility without significantly increasing material loss.

This work investigates the microstructural and mechanical behaviour of Fe–Mn–Al–Cr–C-based low-density stainless steels produced via mechanical alloying and spark plasma sintering (SPS). Fe-Mn-Al-Cr-C based low-density stainless-steel alloys with Mo and Cu were produced using commercially available elemental powders. Spark plasma sintering was used to obtain four alloys with different compositions, Fe-30.9Mn-4.9Al-4.5Cr-0.4 C, Fe-21.3Mn-7.6Al-4.3Cr-1 C, Fe-30.9Mn-4.9Al-4.5Cr-0.4 C-3Mo-3Cu and Fe-21.3Mn-7.6Al-4.3Cr-1 C-3Mo-3Cu. The alloys were sintered at different optimised parameters, temperature (900–1100 °C) and pressure (40 and 50 MPa). Hardness studies were conducted using the strain gradient plasticity approach in accordance with Nix and Gao Model. SEM-BSE and XRD were used to characterise the alloy powder and sintered alloys. The density of the alloys was calculated to be between 91 and 98

In this study, TiVNbCr-based HEAs with Fe and Mn additions were produced by vacuum arc melting and subjected to heat treatment to investigate the influence of alloying and thermal processing on microstructures. CALPHAD calculations, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were employed to evaluate the microstructural characteristics. Results revealed that as-cast alloys predominantly exhibited body-centered cubic (BCC) dendrite regions with minimal to none interdendritic Laves phases, while Fe and Mn-rich compositions favored increased stabilization of C14 Laves phases. Heat treatment at 750°C enhanced atomic diffusion, promoting solute redistribution and significant growth of Laves phases, particularly in alloys enriched with Nb, Cr, Fe, and Mn. The findings highlight the critical role of composition and heat treatment in tailoring BCC/Laves phase balance within HEAS, offering pathways for designing HEAs with optimized hydrogen storage capacity, kinetics, and reversibility.

The integration of sustainable additive manufacturing (AM) within the framework of African industrialization presents a promising avenue for economic advancement while addressing environmental concerns. This review explores the convergence of sustainable AM practices with the industrial landscape of Africa, highlighting potential benefits and challenges. Through efficient resource utilization and localized production capabilities, AM holds promise for enhancing industrial resilience, stimulating employment opportunities, and fostering innovation. However, the realization of these benefits necessitates navigating infrastructural limitations, technological disparities, and regulatory complexities. By critically examining sustainable AM strategies and their relevance to African contexts, this review aims to delineate actionable pathways for leveraging the transformative potential of AM. The role of AM in industrialization as expressed in the African Union Agenda 2063 are highlighted. This has the potential to increase the staggering ∼11% contribution of manufacturing to gross domestic product of Africa. Collaboration through the triple helix approach focusing on government, industry and academia is highly pivotal for the success of such nascent and ubiquitous AM technology which is able to address the sustainable development goals. Africa can leapfrog and harness sustainable AM as a catalyst for inclusive industrial development and sustainable growth across the continent. The implications of AM for an industrialised Africa and areas for future research direction are briefly discussed.

This study investigates the effects of incorporating 5 wt.% molybdenum (Mo) and/or 3 wt% copper (Cu) into low-density stainless steels (LDSSs), with particular emphasis on hardness, microstructural evolution, and corrosion behavior in a 0.9 wt.% NaCl solution. A total of seven austenitic LDSS alloys with two base compositions (Fe-22Mn-3.8Al-0.2C-4Cr and Fe-31Mn-2.5Al-0.1C-4Cr) were produced via vacuum arc melting, with varying Mo and Cu contents. The addition of 5 wt.% Mo resulted in significant grain refinement within the austenitic matrix, whereas 3 wt.% Cu addition led to grain coarsening. The addition of Cu reduced the hardness by approximately 2%, while the addition of Mo enhanced the hardness by up to 35%. The observed increase in hardness due to Mo addition is attributed to grain refinement, while the reduction in hardness associated with Cu addition is linked to grain growth. Electrochemical testing revealed that alloys containing both Mo and Cu exhibited superior corrosion resistance, as evidenced by the lowest corrosion rate recorded at 0.025 mm/year ( I corr  = 2.8 μA/cm 2 , E corr  = −0.379 V), which is well below the threshold of 0.13 mm/year deemed acceptable for biomedical implant materials. These findings suggest that austenitic LDSS alloys containing 5 wt.% Mo and 3 wt.% Cu is a promising candidate for biomedical applications due to its favorable mechanical and corrosion properties.

Biomedical titanium alloys provide a unique mix of favorable biomechanical and biocorrosion characteristics and are lightweight, non-toxic, and highly biocompatible. These qualities make them highly desirable for the fabrication of medical implants. Hot working methods are crucial in producing titanium components as they break down the lamellar microstructure into a finer structure. This phase is essential in shaping the final microstructure and determining the qualities of the components. This review delved into the hot deformability, phase and microstructural evolution, and related constitutive equations used in biomedical titanium flow stress modelling. It describes the counteractive effect of the dynamic recrystallisation (DRX) and dynamic recovery (DRV) deformation mechanisms on the working hardening behaviour of the biomedical titanium alloys after hot deformation processing. It also discusses the effect of forming necklace structures and lamellar kinking structures. Notably, in biomedical titanium alloys, the hot deformation behaviour and dynamic softening effect are significantly influenced by the alloy composition and microstructural characteristics like dislocation movement and grain boundary diffusion. The use of processing maps to identify the instability regime—which includes cracks, flaws and flow instabilities that may arise as the biomedical titanium alloys are undergoing hot processing and to ascertain the best processing conditions is covered in the article. Finally, the article's conclusion includes suggestions for possible future research directions.

The hot workability and deformation behaviour of Cu-Zn-Al-Ni based shape memory alloy (SMA) was investigated. The alloy was isothermal compression tested at temperatures of 250 to 550 , strain rates of 0.1 to 5 s-1, and a constant total strain of 0.5, using a thermomechanical Gleeble-3500 simulator. The results show that positive strain rate sensitivity characterized the plastic flow behaviour of the SMA. The hyperbolic-sine constitutive equation - determined activation energy for the hot deformation of Cu-Zn-Al-Ni SMA (154.34KJ/mol) is about 24% lower than the activation energy for self-diffusion of copper, and that of the stress exponent value (n) which was less than 5, both point to dynamic recrystallization to be the dominant dynamic softening mechanism. Furthermore, the processing map indicated that flow instability occurs in the low temperature and strain rate regions (250 - 350 , 0.1 – 5s-1) with characteristic shear bands, dendritic structures, and micro-cracks in their microstructure. The temperature of 550 and strain rates of between 0.1 and 2.5 s-1, was established to be the optimal condition for hot deformation of the alloy. These conditions result in stable flow with microstructures consisting of fine dynamically recrystallized grains.

MXene-based materials are characterized by excellent superconductivity, superb ion-holding capacity, large surface area, and rapid electrochemical reactions, making them viable options for applications in high-capacity energy storage and conversion systems (ESCS) such as portable digital devices, electric vehicles, power transportation, modern intelligent networks, and 5 G telecommunications. This review article looks at the latest developments and some of the difficulties in the synthesis and modification of MXene-based materials and highlights the transformative role of machine learning (ML) in advancing MXene research and applications. Applications in energy storage and water purification are discussed alongside the economic and industrial challenges of large-scale production. Recent studies confirm that ML models have been instrumental in improving MXene synthesis processes, enabling higher yields and optimization of properties, better purity, and scalability through real-time process control and reinforcement learning. Techniques such as genetic algorithms, evolutionary algorithms, and Bayesian optimization accelerate the discovery of novel MXene phases tailored for specific uses. The review identifies future directions in MXene research, emphasizing the development of scalable fabrication methods, ML-driven material informatics platforms, and the expansion of MXene applications in electronics and beyond. By integrating ML, MXene research is poised to achieve faster, cost-effective advancements and commercialization for next-generation technologies.

This article provides a detailed investigation of the intricate aspects of hot deformation, processing map assessment, and microstructural evolution in aluminum (Al) alloys. It also discusses the application of constitutive equations to forecast flow stress. This article explains how the hot working process can improve the grain structure of aluminum alloys utilizing dynamic recrystallization (DRX), mitigating flaws and strengthening their mechanical properties. Various aspects, such as the development of necklace structures, work-hardening analysis for identifying DRX grains, and the impact of processing conditions on DRX grain size, are thoroughly examined. The microstructural evolution, plastic deformability, and material properties of Al alloys were observed to be impacted by factors such as alloy composition, phase occurrences, deformation processing parameters, and recrystallization mechanisms. The article scrutinizes the use of processing maps to ascertain optimal conditions, addressing the instability regime—encompassing flow instability, defects, and cracking—during aluminum hot-working. Notably, the review delves into constitutive modelling of flow stress, considering factors like deformation strain rates, temperatures, and strain, and examining threshold stress resulting from phase transformation, temperature-dependent Young's modulus, and the alignment of experimentally observed activation energy and deformation stress exponent with values predicted by creep theories. Additionally, the study evaluates various modelling techniques and equations for predicting flow curves in the context of hot-working processing. The article concludes by offering recommendations for potential future research directions.

This study addresses the evaluation of citric acid-treated natural fibres as sustainable additives for improving soil performance in highway construction. A series of tests were conducted on the soil to assess its baseline properties. The natural soil exhibited a Plasticity Index (PI) of 30 and Linear Shrinkage of 12%, along with a Liquid Limit (LL) of 65 and Plastic Limit (PL) of 35. Additionally, the fines content (<0.075 mm) and sand content (0.075-4.7 mm) were determined to be 79.6% and 20.4%, respectively. The soil's mineral composition included Quartz (5%), Orthoclase (3-5%), Montmorillonite (2.6%), and Illite (18.2%), with key components identified through chemical analysis: SiO2 (52.721 wt%), Fe2O3 (16.132 wt%), and Al2O3 (15.202 wt%). Subsequently, a range of tests were performed with varying additives to assess their impact on the soil's engineering properties. The sample containing 6% Sawdust (SD) additive exhibited notable improvements in multiple aspects. This sample achieved a maximum dry density (MDD) of 1856 kg/m3, surpassing the control (1900 kg/m3) and the 10% Rice Husk Ash (RHF) sample (1698 kg/m3). Furthermore, the 6% SD sample demonstrated enhanced Unconfined Compressive Strength (UCS) of 320 kPa, as opposed to the control's 121 kPa. Triaxial shear strength followed a similar pattern, peaking at 41 kPa for the 6% SD sample. The California Bearing Ratio (CBR), the 6% SD sample showcased significant improvements, achieving 41% for Unsoaked CBR and 36% for Soaked CBR. These results outperformed the control (25%) and the 4% RHF sample (37%). Additionally, the hydraulic conductivity of the 6% SD sample was notably lower at 4.98 x10-8 cm/s compared to the control (3.35 x10-8 cm/ s) and the 4% RHF sample (4.58 x10-8 cm/s). The Coefficient of Volume Change (Mv) further supported the superior performance of the 6% SD sample with a value of 0.6, indicating reduced settlement potential compared to the 4% RHF sample (Mv: 0.7). Based on the results, the 6% Sawdust (SD) additive consistently demonstrated the most favourable engineering properties for the expansive clay soil. hence, it is recommended that the 6% SD sample be considered as an optimal choice for enhancing subgrade material, leading to improved performance and sustainability in highway construction.

The potential of refractory high entropy alloys (RHEAs) as high-temperature structural materials depends on optimising their oxidation resistance. This study examines the surface and cross-sectional oxide layers of TiNbTaVW RHEA after five hours of oxidation, comparing them to previously studied layers formed after 15 h. At 850 degrees C, the surface and cross-sectional oxide layers remained crack-free after 5 h, in contrast to the cracked layers observed after 15 h. A crack-free oxide layer effectively slows oxidation by limiting oxygen diffusion. However, at 1050 degrees C, cracks were present in the surface and cross-sectional oxide layers after 5 h, similar to those observed after 15 h. Understanding short-term oxidation mechanisms provides valuable insights for developing strategies to enhance the high-temperature oxidation resistance of RHEAs.

Residual stresses are critical factors influencing the service performance, reliability, and durability of welded carbon steel joints. These stresses can affect the joint, susceptible to brittle fracture, fatigue failure, and stress corrosion cracking, particularly within the heat-affected zone (HAZ). These stresses result from uneven thermal expansion and contraction during welding, with thicker plates and constrained configurations being more susceptible. Post-weld heat treatment (PWHT) assumes a critical function in mitigating these stresses by tempering martensitic structures, refining microstructures, and enhancing mechanical properties such as toughness and ductility. This review examines the mechanisms driving residual stress formation, evaluates the effectiveness of PWHT techniques, and highlights advanced methodologies like neutron diffraction, computational modeling, and hybrid welding processes. While PWHT significantly alleviates residual stresses, complete stress elimination remains unattainable, emphasizing the need for innovative strategies such as hybrid welding methods, computational modeling, and advanced heat treatments. This work integrates metallurgical principles with experimental findings to provide a strategy for enhancing the performance and reliability of welded joints in critically demanding industrial applications.

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 degrees 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 200-270 degrees C/0.01-10 s-1. The stable domain established was at 280-340 degrees C/ 0.01-10 s- 1 which is most suitable for achieving the best microstructural conditions for enhanced service performance.

Metal machining workshops generate a lot of metal chips, which pose both health and disposal challenges. Herein, for the first time, we demonstrate a novel process of reusing lathe-turning steel chips to manufacture high-compression strength Al alloy/steel composites. The process involves melting aluminium alloy onto the steel chips under vacuum and argon gas conditions. Clean and dried steel chips are packed inside a mould with a top layer of aluminium alloy pieces at three different quantity ratios of 80

In this study, CrNbTaVW RHEA was produced via vacuum arc melting. The microstructure, hardness, corrosion and oxidation properties were explored in comparison with the commercial IN718 alloy. The results indicated that CrNbTaVW RHEA exhibited a dendritic microstructure that was segregated into BCC1, BCC2, and Cr(VNb)2 Laves. The CrNbTaVW RHEA has a higher hardness of 688 HV than the IN718 alloy with 301 HV. The higher hardness is due to Laves phase solid solution strengthening and grain refinement. From the corrosion results, CrNbTaVW RHEA had a lower corrosion rate in 3.5 wt% NaCl (0.000097 mm/yr) and 1 M H2SO4 (0.00013 mm/ yr) than the commercial IN718 alloy (0.054 mm/yr and 1.12 mm/yr). The cyclic oxidation analysis at 850 degrees C and 1050 degrees C after 15 hours confirmed a mass gain of 4.41 mg/cm2 and 10.84 mg/cm2 for IN718 alloy, while CrNbTaVW RHEA exhibited a mass loss of -25.17 mg/cm2 and - 35.91 mg/cm2, respectively, indicating that the IN718 alloy exhibited the best oxidation resistance. Thermal and growth stresses contributed to the pores, voids, cracks, and spallation observed in the CrNbTaVW RHEA.