A Zr47Cu40Al8Ag5 bulk metallic glass (BMG) was synthesized using copper mold suction casting and examined for its structural, mechanical, electrochemical, and biological properties. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) have been used to confirm the amorphous nature of BMG. The hardness and Young's modulus, evaluated from Nanoindentation tests, of the BMG are 9.41 +/- 1.59 GPa and 99.5 +/- 5 GPa, respectively. The corrosion behavior of Zr47Cu40Al8Ag5 BMG was evaluated in different simulated body fluids conditions, revealing strong corrosion resistance, especially in Hank's balanced saline solution (HBSS). Biocompatibility was evaluated through MTT assays, surface marker analysis, gene expression studies, and osteogenic differentiation assays using dental pulp stem cells (DPSCs). The BMG showed minimal cytotoxicity, promoted cell viability, and induced osteogenic differentiation, suggesting its suitability for orthopedic and dental implant applications. The combination of good mechanical strength, biocompatibility, and corrosion resistance positions Zr47Cu40Al8Ag5 BMG as a promising alloy material for use in biomedical implants.

The microstructural features of additively manufactured alloys are distinct from those of their conventionally manufactured counterparts, with the combination of the alloy and the processing methods and parameters imparting uniqueness. Herein, we report one such distinct, and hitherto unreported, feature of mesoscale concentric tree-ring-like microstructure within the columnar grains in the Ni-based superalloy fabricated using the laser directed energy deposition technique. Each columnar grain comprises dendrites tens of micrometers in width. Within individual dendrite, cylindrical concentric patterns develop with radial axes perpendicular to the build direction, characterized by relatively coarsened gamma(y) precipitates along concentric walls and finer precipitates between them, producing a tree-ring-like morphology on the laser scan plane. Elemental segregation and dislocation distributions correlate with both the dendritic framework and concentric patterns. Their formation is attributed to the coupled effects of microsegregation-induced intradendritic solvus temperature gradients and thermomechanical cycling that occurs during layerwise fabrication.

Achieving dense atmospheric plasma-sprayed (APS) aluminum-based composite coatings is challenging due to interconnected pores in the conventional coatings that create pathways for corrosive media to penetrate, limiting long-term anti-corrosion performance. In this study, a homogeneously reinforced Al-40 vol% B₄C composite feedstock is developed through mechanical alloying to achieve a homogenously reinforced dense APS deposited coating in the as-sprayed state, which eliminates costly post-deposition processing for densification. The relatively high B₄C content can enable multifunctionality in the coating, as previous studies have shown that increased B4C content results in enhanced radiation shielding. The coating was deposited on AZ31B Mg alloy for electrochemical evaluation and on Al7075 alloy for mechanical testing. The deposition, microstructure characterization, electrochemical behavior, and cohesive strength of the coating is studied. Results indicate that the Al-B4C coating appears pore-free and has a uniform distribution of B4C. The open circuit potential (OCP) of Al-B4C coating is −0.76 V, closely matching bulk Al, which is higher than pure APSed porous Al coating (OCP −1.42 V). Negligible open pores and resemblance of OCP with bulk Al indicate that the Al-B4C coating is dense. While the corrosion potential (Ecorr) of Al-B4C coating is higher than that of pure Al coating, the converse is observed for the corrosion current (Icorr), indicating higher corrosion rates in the former on corrosion initiation due to micro-galvanic interactions between B₄C and the Al matrix. Failure at the glue joint during tensile tests suggests that Al-B4C coating has a minimum cohesive strength of 60 MPa. The combination of near pore-free microstructure, corrosion resistance, strong interfacial bonding, and high B₄C loading highlights the potential of the APSed Al-B₄C coating as a lightweight multifunctional protective layer for marine, aerospace, and nuclear applications requiring both environmental durability and radiation shielding capability.

In the present study, the synergistic effects of scandium (Sc) and zirconium (Zr) additions, as well as the influence of secondary processing (rolling and aging), on the microstructure and hardness of squeeze-cast Al-7Si-0.8Mg alloy were investigated. It was observed that the addition of 0.3 wt.

Repeated and alternating cycles of deep cryogenic treatment (DCT) and room temperature soaking leads to stress mediated nanotwin nucleation in laser directed energy deposition (L-DED) fabricated CrMnFeCoNi high entropy alloy (HEA), which simultaneously enhances its strength and ductility. In this work, the microstructural evolution and mechanical behavior of the as-built and DCT cycled L-DED fabricated HEA after ageing at 773 K is studied. Ageing for 480 h introduces 0.69%, 1.69% and 2.20% volume fractions of complex Cr-rich and NiMn-rich nanoprecipitates in the top, middle and bottom portions of the DCT cycled HEA, respectively, which matches well with the gradient in the volume fraction of nanotwins, V-T, in it. In contrast, a significantly lower volume fraction of nanoprecipitates, f(np), is observed in all portions of the aged as-built counterpart. The yield and tensile strength of the bottom portion of the 480-h aged DCT cycled HEA, which has higher V-T and f(np), are 726 +/- 18 and 909 +/- 13 MPa, which are similar to 370 and 337 MPa higher than those in the top portion. Although the increase in f(np) of the bottom portion enhances strength, it diminishes similar to 9% ductility compared with the top portion. It is deduced that minimization of lattice strain energy drives nanoprecipitation during ageing, following which, an analytical expression to estimate f(np) in the vicinity of nanotwins is derived from classical nucleation theory. Quantitative estimates of strengthening contributions from different microstructural features suggests that precipitate strengthening leads to enhancement in yield strength. Implications of these results in the context of simultaneous enhancement in strength and ductility and some unresolved challenges are discussed.

The effect of solution temperature and cooling rate on the microstructure and coarsening behavior of gamma' precipitates, as well as the hardness of DZ125 Ni-based superalloy is investigated. Microstructural analysis reveals distinct differences in gamma' precipitate morphology between the dendrite cores (DCs) and interdendritic regions (IRs). At lower solution temperatures (1220 degrees C), gamma'-particles do not completely dissolve, leading to the co-existence of primary gamma' (similar to 540 nm) and smaller spherical secondary gamma' (similar to 50 nm) precipitates in IRs, while higher temperatures (1240-1260 degrees C) leads to coarser and more cuboidal secondary gamma' particles. Water quenching, produces finer gamma' particles (similar to 158 nm) near the surface whereas slower cooling methods like furnace cooling results in larger particles due to extended diffusion times. Both the gamma' area fraction, A(gamma'), and the hardness increases with increasing solution temperature and depth. While furnace cooled DZ125 exhibits the highest hardness of similar to 470-480 HV, water-quenched samples have the lowest hardness of similar to 430-440 HV and exhibit a gradient in the hardness along the cross-section. A clear correlation between A(gamma') and Vickers hardness is observed and the solution treatment at 1240 degrees C followed by furnace cooling leads to the highest enhancement in hardness. gamma' coarsening mechanisms are discussed by considering the fits of Lifshitz-Slyozov-Wagner (LSW) model, also known as matrix-diffusion controlled model, and trans-interface diffusion-controlled (TIDC) model. Goodness-of-fit measures reveal that the coarsening kinetics undergoes a transition from LSW near the surface to TIDC in the bulk. These results help in developing heat treatment strategies for directionally solidified Ni-based superalloys.

This study investigates the corrosion behavior of a laser powder bed fusion (LPBF) Al-Mg-Sc-Zr alloy with a Sc/Zr ratio of less than 1 in 3.5wt% NaCl solution. X-ray diffraction (XRD) analysis revealed the presence of an Al matrix with face-centered cubic (FCC) structure and the secondary phase Al3(Sc,Zr) with L12 crystal structure. Microstructural analysis indicated a bimodal grain size distribution with fine equiaxed and columnar grains influenced by thermal gradients and secondary phase Al3(Sc,Zr). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5wt% NaCl solution demonstrated that the alloy exhibits a less negative corrosion potential (Ecorr) and lower corrosion current density (icorr) compared to other Al-Mg-Sc-Zr alloys with higher Sc/Zr ratios, indicating superior corrosion resistance. The enhanced performance is attributed to the fine grain structure and the formation of a stable protective oxide layer facilitated by the higher Zr content.

The present study investigates the effect of Mg addition on the aging and tensile behaviour of squeeze cast Al-7Si-(x)Mg alloys (x = 0-0.8 wt. %). The results show that increasing Mg content leads to a significant enhancement in the peak hardness of the alloys, with the maximum hardness of 149 HV observed for the Al-7Si-0.8Mg alloy after aging for 10 h. Additionally, the study reveals that Mg addition delays the aging kinetics, likely due to the interplay between the optimized number density and size of the precipitates, which require longer aging times to reach their optimal size for maximum strengthening. The tensile strength of the alloys increases with higher Mg content, with the peak-aged Al-7Si-0.8Mg alloy achieving a tensile strength of 337 MPa. The increase in hardness and strength with increasing Mg addition is attributed to the higher number of Mg2Si precipitates formed during aging which hinder dislocation movement. The yield strength of all alloys was predicted using the standard strengthening formula, showing that precipitation strengthening contributes the maximum to the overall yield strength for all the alloys, followed by solid solution strengthening. The present study also reveals the presence of both the beta" and the beta precipitates in the peak-aged samples, suggesting a combined strengthening effect from both precipitates.

The present study investigates the Zr47Cu40Al8Ag4Dy1 bulk metallic glass (BMG) as a potential biomedical implant material, analysing its structural, mechanical, and corrosion properties. The synthesized rod by copper mold suction casting exhibited a fully amorphous structure, confirmed by X-ray diffraction and high-resolution transmission electron microscopy. Nanoindentation tests showed high hardness ( 12.78 GPa) and low elastic modulus ( 88 GPa), suggesting mechanical properties comparable to human bone, which could reduce the stress shielding effect. Nanoindentation analysis also revealed significant elastic recovery (69

The present study deals with the ozone treatment of natural fibres with varying cellulosic contents. The main advantages of performing ozone treatment of cellulosic materials are that it reduces the usage of water, energy and time, since it can physically bleach the cellulosic materials without the need for these essential resources. Also, ozonisation limits the harmful impact on our ecology, basically the chemical oxygen demand values, of the various processes. In addition, ozone treatment is also practiced in the field of natural composites, medical sectors, and in other textile processing areas. In addition, we have mentioned about an industrially scalable machine i.e., ball milling machine required to produce particles from such fibres. This machine can produce sufficient quantity of particles in a quite reasonable amount of time. Furthermore, we have also observed that by ozonising the fibres, makes them more prone to breakage due to removal of lignin and other impurities along with a decrease in their surface energy, making them more brittle. After preparation of the particles we have made composites at different particle loadings and compared their properties with neat ozone treated jute fabric composites. Finally, a brief comparison has been made in terms of creep with composites loaded with different natural fibre-based fillers. The results demonstrate that the ozone-treated jute fabric composite reinforced with sisal filler shows better performance compared to the other natural fibre-filled composites.

The effect of increasing N2 content in the shielding gas on the microstructure and mechanical properties of directed energy deposition (DED) fabricated Ti6Al4V is studied. In the presence of 10 % N2 in the Ar-N2 gas mixture, the melt-pool dimensions are higher than that fabricated in pure Ar at all powers. Irrespective of the N2 content in the gas mixture, all fabricated builds predominantly consist of alpha-Ti laths and traces of beta-Ti. The presence of N2 coarsens the microstructure significantly and randomizes the texture. For upto 8 % N2 injected in the gas mixture, the absorbed nitrogen in the build is only 0.2-0.4 %, but at higher N2 concentrations, TiN phase forms. The compressive strength of the builds fabricated in 2 % N2 and 10 % N2 are 25 % and 100 % higher, respectively than that of the build fabricated in pure Ar, although the presence of N2 completely compromises plasticity. Similarly, there is a 66 % increase in the hardness of the builds fabricated in the presence of N2. The observed improvement in the strength of the builds is discussed in the context of the microstructural changes owing to the absorption of N2 in the alloy during the DED process.

The effect of the number of reinforcement fiber layers on the tribological, mechanical, and thermal properties of needle-punched non-woven jute laminate-reinforced epoxy composite, fabricated via the hand lay-up technique, was assessed. The dry sliding behavior of the composite was evaluated using a pin-on-disc tribometer. The Taguchi method, along with analysis of variance (ANOVA), was applied to determine the optimal combination of tribological testing parameters and identify the most influential parameter. Tensile, flexural, compression tests were performed to evaluate the mechanical performance. Experimental results suggest that increasing the number of fiber layers enhanced the mechanical performance up to a threshold. A further increase in the fiber layer has negatively affected the composite's mechanical performance. Compared to the three-yer reinforcement samples, an increase of approximately 25% in flexural and tensile strength and about 20% in compression strength was observed for the composite with four and five reinforcement layers. The coefficient of thermal conductivity decreased by 10% in five-layered composite compared to the three-layer composite. The tribological performance was not significantly affected by the number of reinforcement layers.

The wear behavior of Ni-based single crystal (NBSC) superalloy SRR99 fabricated by laser-directed energy deposition (LDED) is investigated and compared with that of its cast counterpart. While γ’ precipitate size in the latter is > 400 nm, that in the former is an order of magnitude lower. Dry sliding wear tests reveal that the wear rate and coefficient of friction of the LDED alloy are 75% and 20% lower than that of its cast counterpart, respectively. Detailed transmission electron microscopy investigation of the wear-tested cast alloy indicates that there is orientation change and formation of nanoscale grains only at the top layer of the worn surface, whereas regions below undergo moderate plastic deformation via dislocation slip. In contrast, the sub-surface of the worn LDED alloy has a graded microstructure, with a composite of NiO/γ-Ni on the top, γ’ free nano-grains in the middle, and a highly deformed nanoscale layer at the bottom. The improved wear behavior of the LDED alloy is attributed to its higher dislocation density, finer γ’ precipitates, and the formation of this graded microstructure. Finally, a detailed description of mechanisms that lead to the formation of this unique graded microstructure is provided.

In the quest to achieve net zero emissions, there is a push for using hydrogen as a fuel in mobility and power generation applications. However, when hydrogen interacts with structural metallic components used in these applications, there is a risk of hydrogen-induced embrittlement in them. Additive manufacturing (AM) is an alternate manufacturing method for designing structural metallic components, which offers avenues for tailoring of microstructural features and formation of non-equilibrium phases that have a profound effect on their mechanical properties. Consequently, the interaction of hydrogen with AM fabricated alloys is expected to have a different effect on their structural integrity. This paper presents a comprehensive review of the physical processes and the fundamental scientific principles that govern the metallurgical structure and properties of alloys produced through different AM methods. It then discusses the detection of hydrogen and mechanisms of hydrogen embrittlement in different metallic alloys. Finally, the latest research on hydrogen embrittlement of additively manufactured metals and alloys is summarized.

The constraint factor, C , defined as hardness, H , to the yield strength, ay , ratio, is an indirect measure of the pressure sensitivity in materials. Previous investigations determined that while C is less than 3 for crystalline materials, and remains invariant with change in temperature, it is greater than 3 for bulk metallic glasses (BMGs) and increases with increasing temperature, below their glass transition temperature, T g . In this study, the variations in C for two BMG composites (BMGCs), which have an amorphous matrix and in situ precipitated crystalline ,B-Ti dendrites, which in one case transforms under stress to a"-Ti and deforms by slip in the other, as a function of temperature are examined and compared with that of a BMG. For this purpose, instrumented indentation tests, with a Berkovich tip, and uniaxial compression tests were performed to measure the H and ay , respectively, on all alloys and their constituents at temperatures in the range of 0.48 T g and 0.75 T g . ay and H of the BMGC with transforming dendrites (BMGC-T) increase and remain invariant with increasing temperature, respectively. Alternately, in BMG and the BMGC with non-transforming dendrites (BMGC -NT), the same properties decrease with increasing temperature. BMGC-T has the highest C of -4.93 whereas that of BMGC -NT and BMG are -3.72 and -3.28, respectively, at 0.48 T g . With increasing temperature, C of the BMG and BMGC -NT increases with temperature, but that of the BMGC-T decreases. The values of C and their variations as a function of temperature were explained by studying the variation of pressure sensitivity of the amorphous phase and concluding that the plastic flow in BMGCs under constrained conditions, such as indentation, is controlled by the flow resistance of the amorphous matrix whereas that in uniaxial compression, which is only partially constrained, is controlled by plasticity in both the dendrites and matrix. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Binder-free, flexible electrodes of V2C MXene, V2C-PPy, and V2C-PPy-PdO (a ternary composite of vanadium carbide, polypyrrole, and palladium oxide) were fabricated using a simplified, one-step electrodeposition method. A comprehensive assessment has subsequently been conducted on the microstructural and electrochemical attributes of these electrode materials when utilized in supercapacitors with a 1 M H2SO4 electrolyte. Notably, an impressive specific capacitance of 487F g-1 is achieved for V2C-PPy-PdO ternary composite at 1 A/g. This exceptional performance is due to the considerable active surface area and inherent structural stability of the host material. These factors significantly enhanced the electrochemical reaction kinetics and cyclic reversibility. Furthermore, the V2C-PPy-PdO composite demonstrated a notable specific capacitance of 250F g-1 when integrated into an asymmetric coin cell configuration alongside activated porous carbon under a current density of 1 A/g. Remarkably, it maintained an outstanding capacitance retention of 92 % across 10,000 charge-discharge cycles. Our experimental discoveries were additionally substantiated through the Density Functional Theory calculations, which unveiled that the inclusion of PdO within the V2C-PPy-PdO composite led to an augmentation of electronic states near the Fermi level. This increase in electronic states ultimately improved the quantum capacitance, rendering the V2C-PPy-PdO composite a highly promising candidate for supercapacitor applications.

Crystallization kinetics of Cu46Zr40Ti8.5Al5.5 metallic glass is investigated in non-isothermal and isothermal conditions. In non-isothermal condition, the crystallization activation energy is determined using Kissinger's method. Further, activation energy of reported Cu-Zr-Al metallic glasses are compared with Cu46Zr40Ti8.5Al5.5 alloy to understand the effect of Ti addition on crystallization kinetics. Detailed investigation on activation energy through the crystallization process is studied. To understand the influence of nucleation and growth mechanism during the crystallization steps, samples are heated in isothermal conditions at various annealing temperatures in supercooled liquid region to determine the local Avrami's exponent using Johnson-Mehl-Avrami equation. Additionally, small scale mechanical response is noted on metallic glass sample to determine the influence of structure on hardness and elastic modulus. Nanoindentation results showed hardness value of 5.39 +/- 0.09 GPa and Young's modulus of 92.81 +/- 0.52 GPa.

The room temperature high-cycle fatigue behavior of Haynes 282 subjected to accelerated ageing at 750, 800 and 850 degrees C for different durations was studied. Ageing promotes the growth of gamma' precipitate and the formation of M6C and M23C6 carbides, topologically closed packed mu phase, but has limited influence on the grain growth. Although, fatigue strength increases with increasing ageing duration, at both 750 degrees C and 800 degrees C, contrasting variations in the same were observed with increasing ageing temperature. By measuring the fatigue striation spacings on fractured surfaces and using the results of a finite element model developed for unnotched bend specimens available in the literature, the Paris slopes, m, of aged and unaged samples were determined to be in the range of 3-4. The fatigue crack initiation stage, which is > 99 % of the total fatigue life, increases with increasing size of gamma', except for alloys aged at 800 degrees C and 850 degrees C. Deviations in the trend are attributed to the evolution of M6C carbides at temperatures > 800 degrees C at the MC/gamma interface. Implications of these results are discussed in the context of predicting the fatigue strength of Haynes 282 utilized in service for long durations.

The microstructure, tensile properties, and thermal expansion characteristics of a laser powder bed fusion (LPBF) manufactured compositionally graded composite with 0.5-8 wt% yttria-stabilized zirconia (YSZ) reinforced Inconel 718 are investigated. Along the composition gradient, which is perpendicular to the build direction, in all cross sections, the YSZ segregates at the melt-pool boundaries and the IN718 matrix has randomly oriented equiaxed grains. Cross sections with >2 wt% YSZ contain significant porosity (>2%) and solidification cracks, which reduces their strength and ductility significantly. In the section with 1.5 wt% YSZ, the YS, UTS, and ductility are 819 +/- 30, 1008 +/- 40, and 7.4 +/- 0.4 MPa, which matches well with that of LPBF fabricated YSZ-free IN718. Dilatometry measurements on sections with 0.5-1.5 wt% YSZ in the temperature range of 25-1200 degrees C indicate that their coefficient of thermal expansion (CTE) is intermediate to that of IN718 and YSZ. Finally, the variations in CTE with temperature are discussed in detail by considering the microstructural evolution in the composite with changes in temperature.