This study focuses on the formation and strengthening mechanisms of the heterogeneous interface in high-entropy alloy (HEA)/Al composites, aiming to develop high-performance Al matrix composites with balanced strength and ductility. Thermodynamic and kinetic analyses indicate that HEA/Al composites form the multi-layered heterogeneous interface at 550 °C: Al45Cr7 near HEA-reinforced particles, Al9M2 (M = Co, Fe, and Ni) and Al13X4 (X = Co, Cr, Fe, and Ni) near the Al matrix. The yield strength of HEA/Al composites increases with higher HEA contents, reaching a maximum tensile strength of 150 MPa at 10 vol
FeCoCrNiMo high-entropy alloy (HEA) particles enhance the strength of 5083 Al while maintaining favourable plasticity and toughness. To address the strength–ductility constraints of particle-reinforced 5083 Al-matrix composites, composites were fabricated by hot equal-channel angular pressing (ECAP). The contributions of distinct strengthening mechanisms were quantitatively deconvoluted, the formation mechanism of the interfacial diffusion layer was elucidated, and immersion tests of varying duration were conducted to clarify the seawater corrosion behaviour. The composite containing 15 vol
High-entropy alloys (HEAs) reinforced with ceramics offer strong potential for corrosion-resistant coatings. In this work, TiO2-modified AlCoCrSiNi HEA coatings were produced by mechanical alloying and atmospheric plasma spraying (APS), where the addition of 1 wt
Understanding how defect morphology strongly influences both microstructural evolution and corrosion behavior is essential for establishing a process–defect–property linkage in laser powder bed fusion (L-PBF) 17-4PH stainless steel. In this study, the influence of process parameters and volumetric energy density (VED) on defect morphology, δ-ferrite formation, hardness, and electrochemical behavior was systematically investigated. Quantitative image analysis revealed that lack-of-fusion defects dominate at low VED, while keyhole defects appear at high VED due to excessive energy input. X-ray diffraction and electron backscatter diffraction indicate a BCC-dominant microstructure, which is consistent with substantial retention of δ-ferrite as the primary solidification phase, attributed to the rapid cooling and high thermal gradient inherent to L-PBF. Electrochemical impedance spectroscopy and potentiodynamic polarization tests showed that defect morphology critically affects charge-transfer resistance (Rct) and corrosion current density (icorr), suggesting that interconnected lack-of-fusion pores may provide preferential corrosion initiation sites. The optimized process window (65–75 J mm−3) achieved a dense δ-ferrite microstructure with superior hardness (294 HV) and enhanced corrosion resistance. These findings elucidate the direct correlation between process parameters, defect morphology, and corrosion behavior, providing practical guidance for optimizing L-PBF 17-4PH stainless steel components for service in corrosive environments.
This study investigates the combined effects of corrosion and hydrogen charging on the mechanical performance of two metallic materials—S45C carbon steel and STS316L stainless steel—exhibiting distinct corrosion behavior using indentation. Uniform corrosion was induced in S45C, while STS316L underwent pitting corrosion, followed by cathodic hydrogen charging. Hydrogen uptake was quantified via thermal desorption analysis, and mechanical properties were evaluated using nanoindentation and Vickers hardness tests. In S45C, corrosion reduced hydrogen uptake due to the formation of corrosion products such as iron oxides, leading to a transition from hydrogen-induced hardening to softening depending on the hydrogen content. In contrast, pitting corrosion in STS316L facilitated hydrogen absorption through grain boundary exposure, resulting in localized hydrogen accumulation. This enhanced the hydrogen-enhanced localized plasticity (HELP) mechanism and promoted microcrack formation, particularly in pit-damaged regions. The study reveals that corrosion not only alters hydrogen uptake behavior but also fundamentally modifies hydrogen–mechanical property relationships. These findings highlight the critical need to consider both hydrogen content and corrosion-induced structural degradation when evaluating the reliability of metallic components in hydrogen-rich, corrosive environments.
The hot deformation behavior and dynamic recrystallization (DRX) mechanisms of an equiatomic FeCoCrNiMn high-entropy alloy (HEA) were thoroughly investigated via uniaxial hot compression tests conducted at temperatures ranging from 900 ℃ to 1200 °C and strain rates from 0.01 to 10 s−1. The flow stress behavior was accurately described by a constitutive model based on the Zener-Hollomon parameter, yielding an activation energy of 408 kJ/mol. Processing maps derived from the dynamic materials model (DMM) identified safe deformation domains (1000 ℃–1100 °C/0.01–0.1 s−1 and 1200 °C/0.1 s−1) and instability regions characterized by low DRX fractions and strain localization. Microstructural analyses via EBSD and TEM revealed that discontinuous dynamic recrystallization (DDRX) dominated under most conditions, facilitated by twinning and necklace structure formation, while continuous dynamic recrystallization prevailed at high temperatures and low strain rates. A high density of annealing twin boundaries was observed, particularly under high-strain-rate conditions, which played a critical role in promoting DDRX nucleation. This work provides valuable insights into the DRX mechanisms and hot workability of FeCoCrNiMn HEA, serving as a guide for optimizing thermo-mechanical processing parameters to achieve superior mechanical properties and microstructural control.
The fine metal mask (FMM) used in OLED display manufacturing is a thin metallic sheet with precision holes that enable the deposition of diode materials exclusively onto sub-pixel areas. To prevent deformation and misalignment of the holes caused by heat generated during the RGB organic material deposition process, Invar sheets with a coefficient of thermal expansion (CTE) close to zero are employed. Currently, FMMs are fabricated by rolling to about 20 μm, but this top-down process cannot achieve thinner foils. Therefore, to realize next-generation UHD displays requiring FMMs below 10 μm, a bottom-up electrodeposition method is needed. Achieving both dimensional stability and a low CTE comparable to commercial Invar alloys in electrodeposited ultra-thin Invar sheets requires prolonged high-temperature heat treatment above 600 °C using thermomechanical processing. If the electrodeposited Invar alloy can achieve a homogeneous nanocrystalline microstructure in the as-deposited state, the required heat-treatment temperature and duration can be reduced, improving overall process efficiency. In this study, we investigated the effect of controlling saccharin, a key additive in the Fe–Ni electrolyte, on the microstructural evolution of ultra-thin electrodeposited Invar sheets. By regulating surface stress during electrodeposition, Fe and Ni ion diffusion was promoted, and the relationship between microstructural uniformity and CTE was systematically analyzed.
Off-stoichiometric boron-doped chemically complex intermetallic alloys (CCIMAs) have recently emerged as a new avenue for overcoming the low temperature brittleness of ordered superlattices. However, their behavior at high temperatures remains unexplored. In this study, a novel (Ni39.6Co29.3Cr10Al15.8Ta3.3Nb2)98.5B1.5 CCIMA was prepared and its oxidation resistance over a wide temperature range (500 ℃ –950 °C) was studied. The sample exhibited a dual-phase microstructure consisting of ordered L12 grains and a disordered Cr-rich BCC phase at the grain boundaries. The CCIMA sample demonstrated outstanding oxidation resistance at 500 °C, 750 °C, and 950 °C, showing no signs of pest oxidation and exhibiting low mass gain rates of 8.05 × 10− 5 mg2cm− 4h− 1, 8.97 × 10− 5 mg2cm− 4h− 1 and 5.39 × 10− 4 mg2cm− 4h− 1, respectively. At temperatures above 700 °C, Al2O3 and CrTaO4 oxide layers formed on the surface, significantly hindering further oxidation of the sample. This study demonstrates how chemical composition can be exploited to synergistically develop protective oxide layers on the surface of CCIMAs.
Microstructure, texture and room temperature mechanical properties of hot-extruded Mg-4Gd-xZn (0, 1, 2 wt
Medium alloyed nickel-base superalloy DMR SN 742 was subjected to heterogenization in the sub- and super-solvus region. Microstructural characterization on the heterogenized material revealed the presence of multimodal distribution of γ′ precipitates in both cases however, substantially coarser and widely distributed γ′ precipitates was found in super-solvus heterogenized material. The hot-deformation behavior of both heterogenized materials was evaluated by employing isothermal hot compression experiments in sub-solvus regime at various temperatures (900 ℃–1075 °C) and strain rates (0.001–1/s). Super-solvus heterogenized material exhibited relatively lower resistance to deformation relative to sub-solvus heterogenized material. Based on the flow curves, a mechanistic state diagram correlating temperature-compensated strain rate ‘Z’ against salient strain components (critical strain (εc), peak strain (εp), etc.) has been established to clearly demarcate different regimes of metallurgical phenomena taking place which can be used to design suitable thermomechanical processing schemes. Microstructural investigations on the compressed sub-solvus heterogenized material revealed a number of defects, including shear bands, cavities and wedge cracks along with a few fine dynamic recrystallized (DRX) grains, while the deformation of super-solvus heterogenized was defect free with higher amount of recrystallized grains for similar processing conditions. The apparent activation energy for deformation and the critical strain required for DRX initiation were observed to be less in super-solvus heterogenized material. The differences in the deformation behavior of the heterogenized materials were correlated to the difference in the microstructural features especially the γ′ precipitate size, volume fraction and their distribution which control Zener drag and DRX kinetics. Microstructural evidence identified a wide stable domain for the super-solvus condition and a narrower one for the sub-solvus condition, defining an optimum processing window with direct industrial forging relevance. Post-deformation analysis showed that the γ′ phase remains thermally stable in the super-solvus heterogenized material, while deformation-assisted secondary γ′ formation was observed in sub-solvus heterogenized material, affecting DRX behavior.
In this work, the synergistic enhancement of strength and ductility in a high-Cr Ni-based polycrystalline superalloy was achieved through modulating the precipitation behavior. The optimized alloy with more irregular shape and higher linear density of M23C6 carbide along grain boundaries, higher absolute value of γ/γ’ lattice misfit and higher area fraction of γ’ phase exhibited the best strength and elongation. Firstly, M23C6 carbide along grain boundaries in the optimized alloy, which had more irregular morphology and higher linear density, can efficiently separate micro-voids, leading to the enhancement of pinning effect and improved elongation. Secondly, the stacking fault energy of γ’ phase in the optimized alloy increased, which made greater resistance of γ’ phase to deform. Additionally, the area fraction of γ’ phase and absolute value of γ/γ’ lattice misfit in the optimized alloy were both higher, resulting in a stronger strengthening effect. Therefore, the synergistic enhancement of the strength and ductility of the superalloy was achieved by regulating the precipitation behavior of the precipitates.
Friction stir processing (FSP) was employed to modify the surface and subsurface characteristics of quenched and tempered ultra-high strength AISI 4340 steels. Comprehensive evaluations of microstructure, micromagnetic response, mechanical and tribological properties were conducted before and after processing. Microstructural examination revealed the transformation of the tempered martensitic matrix into a highly refined martensite with the presence of lower bainite and nano-sized carbides structures within the stir zone, with average grain size reduced from 36.5 µm to 1.7 µm due to severe plastic deformation and dynamic recrystallization. Barkhausen Noise (BN) and Hysteresis Loop (HL) analysis confirmed these microstructural refinements through suppressed BN activity, increased coercivity (77.8 to 107.4 Oe), and enhanced remanence (977 to 2345 G), indicative of a magnetically harder martensitic state. Mechanical evaluation demonstrated a marked increase in microhardness, rising from 350 HV in the base material to 770 HV in the FSPed stir zone. Ultimate tensile strength (UTS) improved from 1256 to 1294 MPa, accompanied by an increase in elongation from 18.4
High angular resolution electron backscatter diffraction (HR-EBSD) represents a significant advancement over conventional EBSD, offering two orders of magnitude greater precision in measuring lattice strain and rotation. By replacing the Hough transform with a robust cross-correlation analysis of Kikuchi diffraction patterns, HR-EBSD achieves an angular resolution of approximately 0.0001 radians. This enhanced sensitivity enables the direct quantification of the elastic deformation gradient tensor, which can be decomposed to map residual stress fields with a precision of 20 MPa and geometrically necessary dislocation (GND) densities with a noise floor as low as 1012/m2. This article reviews the fundamental principles of HR-EBSD, highlighting its key distinctions from conventional EBSD. It further explores its primary applications in metallic materials, including the detailed characterization of GND structures, the measurement of micro-scale residual stresses for fracture mechanics. Practical challenges and the theoretical underpinnings of strain and dislocation analysis are also discussed, establishing HR-EBSD as an indispensable tool for linking microstructural features to macroscopic mechanical behavior.
With the ongoing miniaturization of electronic devices, fine patterning technologies have become important. Among various approaches, nano-machining has gained attention for overcoming the limitations of photolithography, offering a cost-effective and simple process compatible with curved surfaces. However, when applied to thin films, adhesion between the film and the substrate becomes critical, as insufficient bonding can cause surface defects and degrade machining accuracy. In this study, a Ti adhesion layer with thicknesses from 0 to 20 nm was introduced to enhance interfacial bonding of 1 μm-thick Cu films on Si and SiO2/Si substrates. SEM analysis revealed that the Ti adhesion layer reduced lateral plastic flow by up to 72
Alloying noble metals such as Pt and Pd with transition metals is a widely employed strategy for enhancing the performance and stability of nanoparticle catalysts. To establish a computational framework for systematically examining those alloying effects, interatomic potentials were developed for the Al–Cu binary system and for Pt- and Pd-based ternary systems (Pt–M1–M2 or Pd–M1–M2, M = Al, Co, Cu, Fe, Mo, Ni, Ti, V) within the second-nearest-neighbor modified embedded-atom method formalism. The Al–Cu potential was optimized against DFT-predicted formation energies, lattice parameters, and bulk moduli, in addition to experimentally measured solid-solution lattice parameters and liquid enthalpies of mixing. The ternary potentials were constructed using a similarity-based averaging scheme and validated against DFT calculations. Using the developed potentials, off-lattice kinetic Monte Carlo simulations were performed to compare the degradation behavior of PtNi and Pt2NiCu nanoparticles. The results show that Pt2NiCu nanoparticles dissolve substantially more slowly than PtNi, primarily due to Cu’s higher oxidation resistance and its ability to suppress interlayer diffusion. Beyond this case study, the developed potentials can be broadly applied to investigate the durability and atomic-scale degradation behavior of a wide range of multicomponent Pt- and Pd-based alloys.
It is a long-term contradiction for room-temperature ductility/formability and high-temperature creep strength in Mg alloys. For the sake of solving this problem without adding high-cost rare-earth elements, this study proposes using twin-roll casting (TRC) method for preparing commercial AZ31 Mg alloy. Common hot-rolling (HR) and recently popular cross-rolling (CR) methods are also performed for comparisons. The results reveal that the TRC sample owns the best synergy of room-temperature plasticity and high-temperature strength. Specifically, the weak rolling texture increases the Schmid factors for basal slip and promotes the ductility/formability of TRC sample. Meanwhile, the obvious solute segregation strengthens the grain boundaries and enhances the creep strength of TRC sample. Inversely, the strong rolling texture induces the poor ductility/formability of HR sample and the lack of solute segregation fails in enhancing the creep strength of CR sample. Therefore, the weak texture and the solute segregation are unveiled to be the two important factors for tailoring the room-temperature ductility/formability and high-temperature creep strength in the TRC-processed Mg alloys. The TRC method is expected to be widely utilized in producing Mg sheets with excellent comprehensive mechanical properties.
In impact engineering domain, it is always critical to evaluate impact events with respect to event location, impactor velocity, and inclination of impactor along with other factors. Such impacts become critical when they are related to safety gadgets of law enforcing agencies and two-wheelers. Law enforcing agencies personals and two-wheel bikers, failure to wear ballistic armor or safety helmets during an accident can cause a direct head injury which leads to life threatening conditions. In addition to this, body armor unavailability possesses a potential life risk in case of hypercritical events. In this review, extensive studies have been carried out from experimental to computational research available in the field of ballistics. Multiple study matrices are developed to compare material systems, different test protocols, and reported outcomes across literature. This review includes different materials utilized in ballistic protections, their manufacturing, experimental characterizations to absorb shock phenomenon, and different finite element methods used till date to computationally evaluate different impact scenarios. The main emphasis in this research is done to see how different advanced materials, Carbon, Glass, Kevlar fibers, Ultra-high-molecular-weight polyethylene and natural fibers with different grades of epoxies have been manufactured, characterized experimentally, evaluated computationally to improve the properties of safety gadgets for multiple ballistic applications. Limitations in terms of materials modelling, their validation also critically analyzed and future framework related to ballistic resistance of materials also proposed.
Ni/Ag–Si and Ni/Ag–SiC multilayer coatings were produced on copper substrates using direct current (DC) and pulse reverse current (PRC) electrodeposition. The PRC process significantly refined the microstructure and resulted in denser and finer grains, while the corrosion current density was reduced by almost 50
The Cu–15Ni–8Sn alloy is widely utilized in marine applications due to its excellent mechanical strength, thermal conductivity, and resistance to seawater and microbiologically influenced corrosion. The addition of yttrium (Y) to the Cu–15Ni–8Sn alloy has been shown to refine the grain structure and enhance mechanical properties, however, its effects on corrosion resistance remain unclear. In this study, the corrosion behavior of a Cu–15Ni–8Sn–0.2Y alloy, fabricated via powder metallurgy, was systematically investigated to assess the influence of Y on seawater corrosion resistance. Multi-scale characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical testing, were employed. After 30 days of immersion in seawater, the measured corrosion rates for Cu–15Ni–8Sn–0.2Y and Cu–15Ni–8Sn alloys were 0.00416 and 0.00498 mm/year, respectively. The Cu–15Ni–8Sn–0.2Y alloy exhibited the lowest corrosion rate, indicating its superior corrosion resistance. Analysis of the corrosion products revealed the presence of metal oxides, including Cu2O, CuO, NiO, SnO2, and Y2O3. The incorporation of Y promoted the formation of Y2O3, which contributed to the development of a denser and more protective passivation film. This film effectively inhibited the adsorption of chloride ions (Cl−), thereby enhancing the overall corrosion resistance of the alloy.
Titanium and its alloys are widely used in orthopedic and dental implants because of their high strength-to-weight ratio, excellent corrosion resistance, and biocompatibility. However, the performance of conventional titanium implants is often limited by bioinert surfaces, insufficient wear resistance, susceptibility to infection, and constraints associated with traditional manufacturing, such as material wastage and lengthy processing times. Additive manufacturing (AM) enables the production of patient-specific, porous titanium implants with enhanced mechanical compatibility. However, AM alone does not significantly improve surface bioactivity, antibacterial properties, or resistance to corrosion and wear. Plasma electrolytic oxidation (PEO) can generate protective, bioactive coatings on titanium surfaces, enhancing wear and corrosion resistance, biocompatibility, and antibacterial performance. The combination of AM and PEO offers a promising approach to overcoming the limitations of conventional titanium implants, enabling the development of next-generation devices with enhanced osseointegration, osteogenic activity, antibacterial functionality, and long-term durability. Despite advances in the field, comprehensive reviews addressing the relationship between the fabrication of AM titanium structures and subsequent PEO surface modification remain scarce, particularly regarding their combined effects on coating composition, structure, and biological performance. This review critically examines AM-fabricated titanium structures with PEO coatings, emphasizing the relationships among processing, structure, and biological and electrochemical performance. We believe this review will serve as a valuable reference for guiding future research and the rational design of advanced AM–PEO titanium implants.
