Porous structures providing proper mechanical performance and biological compatibility are highly demanded for spinal implants. Ti6Al4V gyroid structures with two different unit cell sizes were designed and fabricated by the additive manufacturing laser powder bed fusion. The structures possess pore sizes ranging from 800 to 1500 μm and wall thicknesses ranging from 400 to 700 μm, exhibiting porosity between 67 and 82

The present study investigates the effects of plasma electrolytic oxidation (PEO) followed by physical vapor deposition (PVD) on the corrosion behavior and biological performance of Ti-6Al-4V gyroid scaffolds fabricated by laser powder bed fusion (LPBF). A porous TiO2 layer was first developed via PEO, after which multilayered Nb/NbN coatings were deposited using PVD in various configurations of single and double Nb/NbN layers. While a single Nb/NbN layer maintained the surface morphology of the PEO-treated sample, the deposition of two Nb/ NbN layers decreased the PEO-induced micropore size and resulted in micro/nano-porous features. PEO-TiO2/ PVD-2layers Nb/NbN coating exhibited about a 57% reduction in maximum pore size and a 94% decrease in average porosity compared with the PEO-treated sample. The two-layer Nb/NbN coating showed a higher corrosion current density than PEO alone (4.20 x 10- 7 A center dot cm- 2 vs. 1.30 x 10- 8 A center dot cm- 2), yet still outperformed both the single-layer Nb/NbN coating (1.51 x 10-6 A center dot cm- 2) and the untreated sample (8.68 x 10- 7 A center dot cm- 2). Changing surface topography of samples via PEO/PVD increased their hydrophilicity, thereby promoting in vitro bioactivity of Ti-6Al-4V gyroid scaffolds. Moreover, depending on coating configurations, PEO/PVD showed improved biological performance on Ti-6Al-4V scaffolds. Notably, PEO-treated Ti-6Al-4V gyroid scaffolds coated with two Nb/NbN layers exhibited enhanced MG63 cell viability, reaching 107 +/- 6% (relative to control) by day 7, as well as improved cell attachment compared with the untreated scaffold. Furthermore, PEO/PVD treatment, particularly in samples coated with two Nb/NbN layers, reduced bacterial adhesion on the surface. In overall, deposition of a PEO-TiO2/PVD-2layers Nb/NbN multilayer coating presents an innovative approach for surface engineering of 3D-printed Ti-6Al-4V gyroid scaffolds.

This study investigated the corrosion and tribocorrosion performance of laser powder bed fusion (LPBF)-fabricated Ti–6Al–4V gyroid scaffolds, surface-treated with a TiO2 layer developed via plasma electrolyte oxidation (PEO), followed by a Nb/NbN multilayer coating deposited via physical vapor deposition (PVD). Electrochemical results revealed that the as-built LPBF Ti–6Al–4V scaffolds exhibited lower corrosion resistance than the commercial and LPBF Ti–6Al–4V bulk samples. Surface modification significantly improved corrosion performance. Specifically, PEO-treated and PEO/PVD-treated scaffolds demonstrated 11,000-fold and 1100-fold increases in total resistance compared with LPBF bulk samples. Although the corrosion resistance of PEO/PVD-treated scaffolds was slightly lower than that of PEO-treated counterparts, they outperformed both untreated and solely PVD-coated samples. Tribocorrosion behavior was assessed in a hip simulator using simulated joint fluid and a 15 N load against an Al2O3 ball under open-circuit potential (OCP) and potentiostatic (PS) conditions. Results confirmed that wear was the dominant degradation mechanism. Notably, gyroid scaffolds exhibited enhanced tribocorrosion resistance compared to Ti–6Al–4V bulk samples, with PEO/PVD-treated scaffolds showing the smallest potential drop, lowest corrosion current increase, markedly reduced material loss ( 81

This work deals with evolution of the microstructure and substructure of the IN738LC Ni-based superalloy fabricated by laser powder bed fusion following various post-processing heat treatments, before and after stress rupture testing. The microstructure, primarily composed of γ matrix, γ' precipitates, and carbides, remained stable even after creep rupture. Among the investigated conditions, hot isostatic pressing led to a marked improvement in creep resistance. Post-fracture analyses revealed w-type cracks and r-type defects concentrated along grain boundaries and near boundary precipitates, which were regions of localized micro strain. Several active strengthening mechanisms were identified during high-temperature loading, including dislocation pinning by carbides and γ', Orowan looping, Lomer–Cottrell lock formation, development of dislocation networks, and grain boundary serration. Considering the observation of creep damage at grain boundaries and dislocation activity within the grains, the combined mechanisms of grain boundary sliding and dislocation creep were identified as the governing creep mechanisms at 590 MPa and 760 °C test condition.

Osteosarcoma, a highly aggressive bone malignancy affecting children and adolescents, remains difficult to treat due to drug resistance, systemic toxicity, and high recurrence rates. This study introduces a multifunctional 3D-printed PLGA/PLA scaffold incorporating PEGylated gold nanorods (GNRs@PEG) loaded with doxorubicin (DOX) to enable combined photothermal-chemotherapeutic treatment. Two scaffold formulations were investigated: Target-1 scaffold, consisting of the PLGA/PLA scaffold with uniformly dispersed GNRs@PEG-DOX, and Target-2 scaffold, which includes an additional chitosan (CS) hydrogel coating to enhance hydrophilicity and biological interactions. Target-1 scaffold exhibited increased surface roughness and a compressive strength of 57 MPa, whereas Target-2 scaffold demonstrated higher water uptake and improved flexibility due to the CS layer. Under 810 nm NIR irradiation, both scaffolds efficiently converted light to heat (≈48–51 °C), enabling on-demand DOX release and inducing apoptosis in MG63 osteosarcoma cells. The combined PTT + DOX treatment reduced MG63 viability to below 20%, indicating a pronounced therapeutic enhancement. These results highlight the potential of GNR-integrated 3D-printed scaffolds as promising platforms for localized osteosarcoma management.

This study presents the first systematic investigation of the cryogenic tensile behavior of Hastelloy X (HX) Ni-based alloy fabricated via laser powder bed fusion (LPBF) additive manufacturing, revealing how strategic control over scanning patterns and heat treatment routes can be used to engineer microstructures that enhance mechanical performance at -196 degrees C. Specifically, two scanning strategies (meander and island) and two thermal post-processing conditions, (i) stress relief (900 degrees C for 2 h) and (ii) stress relief followed by solution annealing (1175 degrees C for 2 h), were implemented. While previous studies focused primarily on high-temperature applications of LPBF HX, this work uniquely targets the extreme cryogenic regime, uncovering microstructural mechanisms critical for ductility and work-hardening behavior. The findings demonstrate that island scanning produces coarser grain and cell structures, which facilitate deformation twinning and improve cryogenic ductility compared to meander-patterned samples. Moreover, dual-step heat treatment induces recrystallization and twin formation while dissolving Mo-rich phases and dislocation substructures. Remarkably, the combination of island scanning and dual heat treatment yields a synergy that enables exceptional strength-ductility balance and enhanced twinning-induced plasticity effect, a mechanism not previously reported in additively manufactured HX alloys at cryogenic temperatures. These results provide a novel pathway for microstructure-based optimization of Ni-based alloys for extreme service environments.

The high-temperature tensile properties of the IN738LC alloy fabricated by laser powder bed fusion (LPBF) process was evaluated in terms of strengthening mechanisms and factors influencing alloy deformation in two post-processing conditions: standard heat treatment (HT), and hot isostatic pressing followed by standard heat treatment (HIPHT). The microstructure of both types of samples consisted of gamma matrix, gamma' precipitates, and carbides; however, the amount and distribution of these features varied depending on the type of heat treatment. It was found that cracking in both HT and HIPHT specimens was initially caused in regions where adjacent grains exhibited heterogeneous deformation. The contribution of various deformation and strengthening mechanisms was determined through microstructural evaluations by transmission electron microscopy along with calculation of critical resolved shear stress. Mechanisms such as precipitate shearing, Orowan looping, and multiple structural interactions between matrix, precipitates, carbides, and dislocations, contribute to the high-temperature tensile deformation and strengthening of the LPBF-fabricated alloy. Microstructural characterization indicated that the coherency between the gamma and gamma' phases has the most significant impact on high-temperature tensile strength.

Accurate prediction of solidification microstructures is essential for optimizing laser powder bed fusion (LPBF) process. We present a coupled multiscale framework combining finite volume melt pool simulations with a two-dimensional microscopic phase-field (PF) model. The process-scale model captures transient heat transfer and Marangoni convection, providing local solidification parameters including temperature gradient (G) and growth velocity (V) that directly drive microstructure simulations. Single- and double-track LPBF experiments were conducted on 316L stainless steel under comparable thermal conditions providing model validation. It is shown that increasing laser energy density under conduction mode results in deeper melt pool penetration, enhanced Marangoni convection, cell size enlargement, and more defined cellular structures, collectively promoting melt pool stability and dimensional growth. Results reveal distinct behaviors for successive scan tracks: the second track develops a wider, shallower melt pool due to residual heat and asymmetric boundaries, leading to reduced cooling rates. Simulations capture planar-to-cellular transition and predict primary arm spacings consistent with Hunt and Kurz–Fisher models. Comparison with micrographs confirms that the model reproduces spatial variations in grain morphology and solute segregation. This work demonstrates that a physics-informed CFD–PF coupling, together with a pseudo-binary alloy approximation, enables reliable yet computationally efficient microstructure prediction in LPBF.

ABSTRACT This study explores Poly(lactic‐co‐glycolic acid) (PLGA)‐based scaffolds modified with 10 wt% polycaprolactone (PCL), polylactic acid (PLA), and polyurethane (PU) to enhance their performance. The composite films were characterized by tensile testing, degradability, water absorption, thermal stability, and cell viability. The PLGA/PU group exhibited improved flexibility, while PLGA/PLA showed optimal water absorption (28%) and increased wettability. Contact angle measurements revealed a reduction in hydrophobicity for the PLA (44.4 ± 1 degrees) and PU (43.3 ± 1.6 degrees) groups. Thermal analysis confirmed enhanced thermal resistance for the PLGA/PLA and PLGA/PU composites, making them suitable for applications requiring thermal stability. Additionally, the MTT assay demonstrated over 90% cell viability for the PLGA/PLA group, underscoring its biocompatibility. These findings highlight the potential of PLGA/PLA composites for bone scaffold applications, particularly in additive manufacturing. This study demonstrates that incorporating PLA into PLGA improves key scaffold properties and offers a versatile material for advanced bone tissue engineering.

In this study, failure mechanism under tensile loading of the joint interfaces Cu-AISI4140 steel fabricated by spark plasma welding (SPW) is investigated. The SPW process was conducted at 700 degrees C and a pressure of 20 MPa for durations of 5, 15, 30, and 60 min. Tensile loading was applied to evaluate mechanical properties of the joints. Microstructural analyses of the joints were performed using scanning electron microscopy, while the fracture surfaces of the samples after tensile testing were examined using field emission scanning electron microscopy. Grazing incidence X-ray diffraction was employed to identify phases at the joint interface on fracture surface of the joints. The results revealed that the SPW process facilitated the forced mixing of Cu in steel and Fe in Cu, without formation of any inter-metallic compound at the joint interface. Additionally, strength of the joint formed over a 60-min duration approached that of Cu. Examination of the fracture surfaces indicated brittle failure in the elastic zone for joints formed over a 5-min duration. As the process time increased to 15 and 30 min, brittle and ductile ruptures occurred, respectively, before reaching the maximum stress in the engineering stress-strain curve. In the joint formed over a 60-min duration, rupture did not occur at the joint interface before reaching the maximum stress in the engineering stress-strain curve. Instead, with the development of micronecking at numerous areas of the joint interface, ductile failure occurred after reaching the maximum stress.

Alumina nanoparticles were incorporated into CoNiCrAlY powders to fabricate an overlay coating of improved oxidation resistance for gas turbine blades via thermal spraying. In this regard, 6 wt.

This research aimed at the microstructural characterization and elucidation of roomand high -temperature tensile properties of additively manufactured Hastelloy X Ni -based superalloy heat-treated at 900 degrees C. The samples were fabricated via the laser powder bed fusion method utilizing two scan strategies known as island and meander types. The results indicated that the cellular structure embedded in the columnar grains of the as -built microstructure disappeared after applying the heat treatment, linking to the reduction in dislocation density while keeping the former morphology of the grains unchanged. However, the intensities of the Brass, Goss, GossBrass, and rotated Goss texture components were reduced, leading to the generation of more homogenous fibers in the heat-treated microstructure. Additionally, it caused the formation of a Mo-rich phase on the grain boundaries, which improved the room temperature's ultimate tensile strength. However, it was elucidated that the Mo-rich phase-induced void formation and intergranular cracking failure caused a slight decrease in hot ductility. Overall, the obtained results revealed that the heat-treated island samples showed superior hot tensile behavior than the meander sample due to having a larger grain size.

Cracking is one of the most important challenges in the laser powder-bed fusion (LPBF) processing of high-γʹ nickel-based superalloys. In this work, crack susceptibility of the IN738LC superalloy fabricated by LPBF with different volume energy densities (VEDs) was investigated. It was observed that processing with medium VEDs (∼90 J/mm3) and higher scan speeds resulted in higher relative densities and lower defects. Cracks were mostly observed in grain boundaries with higher misorientation. Al oxide and MC carbides also were observed close to the crack area as stress concentration sites. Residual stress measurement using XRD also confirmed presence of tensile residual stresses in the as-built samples. Lower amount of residual stress in the sample associated with higher crack density was attributed to stress relaxation due to crack nucleation and growth. The majority of cracks in the IN738LC microstructure was found to be solidification cracks.

Alumina nanoparticles were incorporated into CoNiCrAlY powders to fabricate an overlay coating of improved oxidation resistance for gas turbine blades via thermal spraying. In this regard, 6 wt.% alumina nanoparticles were agglomerated with CoNiCrAlY powders by modified suspension route and applied to samples of CMSX-4 nickel-based superalloy by high velocity oxygen fuel (HVOF) process. The coatings were characterized by X-ray diffraction, scanning electron microscopy and field emission scanning electron microscopy, EDS and elemental mapping, Vickers hardness and roughness measurement. Cyclic oxidation tests were performed to study the high-temperature oxidation behavior at 1100 degrees C. The results showed an increase in hardness, roughness and porosity with the addition of alumina nanoparticles to the coating. Furthermore, the oxidation resistance of CoNiCrAlY + 6 wt.% Al2O3 was improved as compared to conventional CoNiCrAlY after 100 cycles of oxidation; a reduction in the thickness of oxide layer and beta depletion zone was observed. Formation of a dense and protective alpha-Al2O3 phase, instead of theta-Al2O3, was confirmed during the oxidation process in the coatings containing nanoparticles. It was concluded that nanoparticles prevent the penetration of elements to the surface and reduce the formation of non-protective oxide layer.

In this study, we conducted in-situ tensile deformation tests using synchrotron X-ray and neutron diffraction techniques on Nb-bearing AISI 201 austenitic stainless steel specimens with varying grain sizes, including ultrafine (UFG, 0.28 μm), fine (FG, 1.75 μm), and coarse (CG, 110 μm) grains. The primary objective was to investigate the effect of grain size on the evolution of lattice strains and deformation mechanisms. Our findings reveal that grain size significantly impacts the evolution of lattice strains, peak broadening, and the distribution of load between the austenite and martensite phases. Notably, the average lattice strain and peak broadening were found to be higher in the CG specimen compared to the UFG and FG counterparts. While the lattice strains in the UFG and FG steels are all compressive, a tensile manner can be seen for the CG steel as deformation proceeds. The strain-induced martensite transformation kinetics for the reversion-annealed UFG and FG steels was higher than that of the solution-annealed CG one. A soft behavior from reflection (200) was found compared to other reflections in all UFG, FG, and CG specimens, showing anisotropic elastic properties. The analysis of lattice strain and peak broadening evolutions indicated that dislocation slip predominantly governs the deformation mechanism in the CG steel, while strain-induced martensitic transformation and twinning are more prominent in the UFG and FG specimens.

Gold nanostructures play a crucial role in medical applications, harnessing size and shape-dependent properties. A prominent area of research is cancer treatment through the photothermal approach. Here, numerical simulation is explored to study the impact of gold nanostructure size, shape, and laser parameters on spatiotemporal temperature patterns during photothermal therapy (PTT). Spherical, rod, star, bipyramid, and cubic nanostructures in small, medium, and large sizes underwent 150 s of laser irradiation. COMSOL software, incorporating bioheat physics, precisely gauged thermal variations. The structural characteristics notably influence the temperature profiles, with medium-sized rod, star, and bipyramid gold nanoparticles exhibiting superior thermal properties. Experimental validation of simulations focuses on the optimal nanostructure, synthesizing through the seed growth method. Transmission electron microscopy, UV-visible spectroscopy, and X-ray diffraction analysis confirm its proposed characteristics. Results demonstrate a robust correlation between experimental and simulation parameters, affirming precision. Findings showcase photothermal properties in line with theoretical predictions. The aim of this study is to determine the optimal gold nanostructure for bone cancer treatment using PTT, addressing the challenges presented by the dense and resilient nature of bone tissue and deep tumor locations. By utilizing multi-physical modeling and simulations facilitated by COMSOL software, a novel method for pre-clinical estimation is introduced. This research provides insights into each nanoparticle-based PTT process prior to ex vivo and in vivo studies, offering a comprehensive understanding of the interplay between nanostructure characteristics and PTT outcomes. The approach contributes to advancing the field of cancer treatment by enhancing the predictability and effectiveness of nanoparticle-mediated PTT. The study evaluates gold nanostructures for the treatment of bone cancer using numerical simulations and experimental validation. Gold nanostructures, in various shapes and sizes, are studied through COMSOL multiphysics simulation based on their unique optical properties, and experimental analysis confirms their effectiveness. The results of this study provide a new approach to optimizing photothermal therapy in challenging bone cancer treatments. image

Despite the numerous advantages of additively manufactured Ti-6Al-4V porous implants surface modified by plasma electrolyte oxidation (PEO) coatings in biomedical applications, several challenges still persist regarding their tribological and fatigue performances. To address these challenges, this study aims to engineer an innovative multilayered coating based on physical vapor deposited (PVD) Nb/NbN coatings on PEO-treaded Ti-6Al4V porous implants. Three configurations of Nb/NbN coatings, including one, two, and three PVD layers were deposited on PEO-treated Ti-6Al-4V implants to simultaneously assess the effects of both increased coating thickness and configuration on the surface topography and mechanical performances of Ti-6Al-4V implants. Results showed that increasing the thickness and number of coatings changed the surface morphology and reduced the surface roughness. The PVD/PEO treatment demonstrated enhanced wear resistance of Ti-6Al-4V samples compared to the PEO treatment, depending on the coating conditions. Noticeably, the samples with 2 Nb/NbN layers exhibited the highest wear resistance and decreased the wear rate by 90 % compared to the Ti6Al-4V samples. Although PEO treatment resulted in a decrease in fatigue life, the deposition of Nb/NbN coatings, especially those with 2 and 3 layers, markedly improved fatigue resistance compared to the PEOtreated samples. These modified samples attained approximately 81 % and 84 % of the fatigue life of the nottreated Ti-6Al-4V samples, respectively. Overall, the deposition of multilayered PVD Nb/NbN coatings on PEO-treated Ti-6Al-4V implants demonstrated an effective improvement in wear resistance while maintaining acceptable fatigue life under cyclic loading, making it promising for biomedical implants.

The synergic effects of scanning pattern types and subsequent heat treatment on the room- and elevated-temperature tensile properties of powder bed fusion-laser beam additively manufactured Hastelloy X Ni-based superalloy are investigated. The samples were built via bi-directional and chessboard scanning patterns. The as-built microstructures comprised dislocation and solidification cells embedded within the columnar grains. After applying heat treatment at 1175 °C for various soaking times, the as-built microstructures were gradually modified via recrystallization resulting from the residual stresses. The recrystallization kinetics equations for both bi-directional and chessboard samples were derived. It was found that the recrystallization occurred via the twinning-assisted nucleation mechanism and was promoted through bulging. The chessboard and bi-directional samples had similar driving forces; however, the recrystallization fraction in the chessboard sample was higher than that of the bi-directional sample due to differences in the grain’s micro-texture. It was observed that the heat treatment cycle had no significant influence on the room- and high-temperature strength; by contrast, it interestingly improved the room- and high-temperature ductility due to reduced dislocation density and formation of twin boundaries. In addition, the heat-treated chessboard sample displayed superior hot tensile ductility than the bi-directional ones, owing to more promotion in recrystallization.

To achieve high performance in perovskite solar cells (PSCs), it is very vital to engineer the recombination and extraction of the hole–electron pairs at the electron transport layer (ETL)/perovskite interface. In this research, the main idea is to improve the photovoltaic performance of the cells by modifying the compact ETL surface (≈50 nm thick) by inserting a <10 nm thick ultra-thin layer (UTL) of metal oxide. For this purpose, all types of single layer and bilayer structured ETLs of TiO2, SnO2 and WO3, i.e., three common metal oxide electron transport materials in PSCs, were fabricated using the reproducible and industry-compatible radio-frequency sputtering method and their function as ETLs was then compared. These ETLs and cells were characterized for structural and electrical properties by FESEM, XRD, Mott–Schottky analysis, UV–Vis spectroscopy and J–V measurements. It was found that a significant increase in cell efficiency is achieved due to more efficient energy band alignment using the bilayer structures of TiO2/WO3-UTL, SnO2/WO3-UTL and TiO2/SnO2-UTL. Conversely, reduced efficiency is observed when using their inverted structures, namely WO3/TiO2-UTL, WO3/SnO2-UTL and SnO2/TiO2-UTL. These results suggest a simple and promising strategy to increase the efficiency of photovoltaic devices.

The mechanical performance and corrosion behavior are crucial factors for additively manufactured Ti-6Al-4V porous implants, which are influenced by implant design, fabrication method, and post-processing. In the present study, effects of geometrical pa-rameters and heat treatment on the compression and corrosion behaviors of Ti-6Al-4V sheet-based gyroid implants fabricated by laser powder-bed fusion (LPBF) process are investigated. The results showed that an increase in the pore size (ranging from 600 to 1200 mm) did not alter the microstructure, while decreased the Young's modulus and strength of the implants. The post-processing heat treatment resulted in the a' / a thorn b phase transformation which influenced mechanical properties. The mechanical properties of all scaffolds were found to be comparable to those of human bone. The heat-treated implants showed superior corrosion resistance than the as-built ones. Furthermore, the corrosion resistance of both as-built and heat-treated implants improved with increasing the pore size. The LPBFed Ti-6Al-4V implants with gyroid-sheet structure can be a promising candidate for biomedical implants from both compressive and corrosion be-haviors points of view. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).