The corrosion behaviour of industrially-produced 316 L stainless steel in 0.01 M NaCl solution was investigated using scanning electrochemical cell microscopy (SECCM) under potentiostatic conditions (+1.2 V vs Ag/AgCl, 60 s). Variations in micro-droplet footprint size during sequential SECCM measurements created an oxygen gradient at the metal-electrolyte interface, enabling systematic investigation of the effect of the oxygen supply rate, or aeration, on both general corrosion and metastable pitting kinetics. Chronoamperometric data from 205 individual measurements were analysed using custom quantitative descriptors and Linear Discriminant Analysis (LDA) of EBSD-derived crystallographic features. Manual classification of 91 transient events into two distinct categories - "peak" (metastable pitting) and "belly" (passive film thinning) - combined with data-driven analysis revealed previously hidden correlations. Higher aeration conditions (smaller droplets, 2-3 mu m) produced 20 % higher oxygen flux compared to lower aeration (larger droplets, similar to 8 mu m), leading to increased initial dissolution currents and faster passive film formation. However, these rapidly-formed films exhibited persistently elevated passive current densities, while higher aeration conditions produced longer-duration belly-type transient events, revealing a trade-off between passive film protectiveness and repassivation capability. Strong correlations between early-time electrochemical descriptors and total corrosion charge suggest potential for rapid, non-destructive corrosion susceptibility assessment. These findings reveal distinct relationships between oxygen availability and corrosion behaviour.

This work explores the early stages of corrosion in a low-alloy steel produced by Wire Arc Additive Manufacturing (WAAM). Specimens were exposed to a marine environment, and the influence of non-metallic inclusions on corrosion was examined. Although Mn-silicates are commonly reported in additively manufactured steels due to rapid solidification, they are generally considered inert with respect to corrosion in some AM steel grades, such as stainless steel. For the present work, however, it was observed that in the case of WAAM low-alloy steel, these inclusions can contain small MnS-rich regions that act as preferential sites for pitting corrosion initiation, due to their chemical instability. As the exposure time in a marine environment increases, the metallic matrix surrounding MnS-rich regions undergoes localized dissolution, leading to inclusion detachment and pit formation, followed by the development of a surrounding circular corrosion front. This front progressively spreads, encompassing and detaching adjacent inclusions, ultimately transitioning from localized to general corrosion.

The microstructure-mechanical property relationships of alpha+alpha ' dual phase microstructures are studied in Ti-6Al4V. Various annealing temperatures in the alpha+(3 field are analyzed and the decomposition of the metastable martensite phase is also investigated. Low annealing temperatures lead to large work-hardening that is attributed to the occurrence of the concurrent deformation of a composite structure where the martensite is the softer phase and the occurrence of Reorientation Induced Plasticity in the martensite (RIP effect). This is studied by Electron Backscattered Diffraction (EBSD) and in-situ tensile testing combined with Digital Image Correlation (DIC). High annealing temperatures lead to a large decrease in work hardening due to the disappearance of RIP and of the mechanical contrast between alpha and alpha'. Further annealing of the alpha+alpha' microstructures goes along with the disappearance of RIP associated with the decomposition of the metastable martensite. The decomposition mechanism is shown to be a reversion phenomenon with the (3 phase precipitating within the martensite and at interfaces while retrieving its high temperature orientation. The precipitation of the (3 phase is shown to largely increase the strain to fracture of the samples annealed at high temperatures. The precipitates act as reinforcement of the larger laths that form within the large (3 grains associated with the high annealing temperatures.

Zinc oxide in nanometric dimensions, thanks to its optical properties, is an oxide of great interest for its potential use as a revealing agent for latent fingerprints. In this article we present the synthesis and characterization of ZnO nanoparticles obtained by two methods and it uses in revealing of latent fingerprints on non-porous surfaces. The nanoparticles synthetized present an atomic Zn:O ratio of 0.99 and 1.15 when precipitation and combustion in solution method were used, respectively. Both samples show a hexagonal arrangement (wurtzite) according to the X-ray diffraction and Raman spectra. Raman results show a shift at 439 cm−1 corresponding to the E2 (high) mode of the ZnO crystalline hexagonal wurtzite structure. Transmission electron microscopy images show that nanoparticles with smaller average diameters are obtained by chemical precipitation (17.2 ± 10.8 nm) than combustion in solution (73.4 ± 6.0 nm). Samples presented a narrow band gap of 3.69 and 3.59 eV, values higher than that reported for the bulk material (3.37 eV). The photoluminescence spectrum showed a characteristic ultraviolet emission peak around 387 nm and green emissions peaks from ZnO when excitation wavelength of 325 and 488 nm were experiment, respectively. Finally, ZnO nanoparticles were used to reveal latent fingerprints on non-porous surfaces using a 325 nm laser. Fingerprint development is better on black glass surface when using precipitated ZnO. However, Fingerprints are better observed in aluminum foil when ZnO obtained by combustion in solution is applied. The results show that it is possible to use ZnO nanoparticles obtained by both methods as latent fingerprint revealing agents.

This study investigates the corrosion behaviour of an additively manufactured (AM) Al-Fe-Zr alloy produced by laser-based powder bed fusion (PBF-LB). The alloy was developed to target high strength and conductivity applications and as a substitute for conventional 6xxx series alloys, which suffer from hot cracking during PBF-LB processing. Multiscale characterization (SEM, EBSD, SKPFM, XPS, and electrochemical testing) revealed that the rapid solidification during PBF-LB produces a highly refined microstructure with nanoscale Fe-Al intermetallic particles (IMPs), resulting in a narrow surface Volta potential range. These features contribute to enhanced electrochemical homogeneity and reduced susceptibility to localized corrosion compared with conventional AA6060. Potentiodynamic polarization tests in NaCl solution indicated comparable overall performance between the AM Al-Fe-Zr alloy and AA6060, while immersion tests demonstrated that the AM alloy exhibited lower pitting susceptibility, attributed to microstructural refinement and the modified composition of the native oxide film. XPS analysis confirmed the incorporation of Fe- and Zr-based oxides into the native film, potentially improving stability and supporting the enhanced corrosion resistance of the AM alloy. Nonetheless, heterogeneities were observed at the level of the melt pools, with the melt pool boundaries (MPBs) presenting coarser IMPs and inclusion-free zones (IFZs). These regions acted as preferential sites for localized attack, occasionally aligning corrosion along MPBs.

Titanium dioxide in its anatase form is of significant interest nowadays due to numerous properties such as biocompatibility, photoactivity under ultraviolet irradiation, or corrosion resistance. In this paper, titanium dioxide (TiO2) films are synthesized with a controlled substrate temperature going up to 673 K. Crystalline anatase was synthesized in a low power atmospheric pressure dielectric barrier discharge in a single step process. The effect of deposition parameters (plasma gas, the voltage input, precursor flow, deposition time, and substrate temperature) on the crystal size, crystallinity, and coating morphology was studied. It shows that the crystal size can be tuned, that the layers can have a transition from hydrophilicity to hydrophobicity, and that the coating morphology can be modified by optimizing these parameters. Finally, it is found that crystalline anatase TiO2 can be grown at a substrate temperature as low as 523 K in an atmospheric pressure plasma enhanced chemical vapor deposition process.

Zirconium is used in the nuclear sector due to its low neutron absorption properties. Alloying elements must be added and combined with thermomechanical processing (TMP) to impart the necessary properties for this application. To enhance the performance of these alloys in service, optimizing new compositions and their processing is essential. This study investigates the effect of manganese on crystallographic texture as a partial replacement for Nb in a Zr–Nb alloy. Alloys with compositions of Zr–0.9Nb–0.1Mn, Zr–0.8Nb–0.2Mn, and Zr–0.6Nb–0.4Mn were hot and cold-rolled to produce sheets, followed by final annealing. The distribution of strains through the thickness of the sheets was assessed using computational simulation. Bulk crystallographic texture was measured by X-ray diffraction (XRD) at key stages of TMP, while microstructure and the fraction of high-angle grain boundaries (HAGB) were characterized using electron backscatter diffraction (EBSD). The results indicate that increasing the Mn content did not promote certain desirable crystallographic texture characteristics, including: the absence of significant texture development during hot rolling, basal pole tilt towards the transverse direction (TD) during cold rolling, and the persistence of this tilt after annealing, accompanied by a reduction in texture intensity from 6.7 to 3.7. Conversely, the Zr–0.9Nb–0.1Mn alloy exhibited a crystallographic texture development closer to that of Zr–1Nb, resulting in a higher fraction of basal poles oriented parallel to the normal direction (ND) of the sheet, with a Kearns factor fND = 0.4726. EBSD analyses indicated that the Zr–0.6Nb–0.4Mn alloy presented a fully recrystallized microstructure with an HAGB fraction of 0.912, while the Zr–0.9Nb–0.1Mn alloy exhibited a bimodal microstructure with an HAGB fraction of 0.588. Transmission electron microscopy (TEM) revealed two types of precipitates: β-Nb, which is typical in Zr–Nb alloys, and Mn2Nb, present in all compositions. The results suggest that Mn addition close to 0.1 wt pct is promising for the development of new zirconium alloys for nuclear applications.

The effect of different yttrium addition on the microstructure and creep resistance of alloy 718 was evaluated aiming to obtain superior creep properties. Creep tests were performed and microstructural characterization was carried out on the samples before and after creep, using scanning, transmission and orientation imaging electron microscopy. The results showed that yttrium addition increased the rupture time and decreased the minimum creep rate. It was related to the microstructural changes caused by yttrium, such as the reduction of grain boundary sliding due to the grain growth rate increasing, which generated fewer secondary cracks at the triple points; the decrease in the stacking fault energy of the alloy that difficulted the slip mechanism. Moreover, Y caused the improvement in cohesion and strengthening of grain boundaries, decrease in the initial fraction of delta phase, increase in the fraction of Sigma 3n boundaries and the additional contribution to boundary trapping due to precipitation of the Ni5Y phase.

While work-hardening is typically considered in Ti as a prerogative of the 13 -metastable alloys, this paper introduces a novel perspective, presenting a set of alloy design rules to develop solute lean alpha + 13 titanium alloys exhibiting increased work-hardening capabilities. More specifically, reaching this goal is made possible through the development of alpha + alpha ' microstructures exhibiting Reorientation Induced Plasticity (RIP) within the alpha ' martensitic phase. The microstructural requirements for activating RIP and maximizing mechanical properties (i. e., combining high work-hardening, yield strength and ductility levels) are derived from an analysis of the microstructures/mechanical property relationships of various alpha + alpha ' samples. A set of design rules is provided. Emphasis is laid on the pivotal role of the chemistry of the alpha ' martensitic phase in RIP activation and a Molybdenum equivalent chemical criterion is proposed. The alpha phase is here suggested as a mean to reduce the prior 13 grain size and the resulting size of the martensite plates. This approach reveals that the versatile thermal treatments leading to alpha+alpha' structures broaden the mechanical property landscape, achieving large work hardening capabilities (typically over 500 MPa) that can be combined with high yield strength (over 800 MPa).

Recent experiments identified a new type of stress induced structural transformation allowing to combine high strength, great work hardening and good ductility in multiphase Ti alloys. These properties are achieved through reorientation of the alpha' martensite plates being in specific self accommodating < 5 (4) over bar(1) over bar3 > type II twin relation, i.e. under applied load one martensite variant reconfigure to its twinned configuration with visible motion of the {13 (4) over bar1} twin boundary. This mechanism of plastic deformation was never observed before thus, its current understanding is fragmentary. In this article we present the results of experimental observations and ab initio calculations of < 5 (4) over bar(1) over bar3 > type II twins determining the crystallography of twin formation, structure and energy of the {13 (4) over bar1} interface as well as mobility of the corresponding twinning disconnections. It was found that the investigated boundary has one of the lowest energies among known twinning modes in hexagonal Ti. Moreover, the < 5 (4) over bar(1) over bar3 >{13 (4) over bar1} disconnections have the smallest Burgers vector and step height in comparison to other active twinning systems. As a result, these disconnections are highly mobile which rationalize migration of the {13 (4) over bar1} twin boundaries at straining. Furthermore, energy of the twin boundary and mobility of disconnections can be adjusted by particular alloying elements enabling the conscious development of new alloys exhibiting reorientation induced plasticity.

A Fe-30.5wt%Ni-0.155wt%C alloy was annealed at two different temperatures to produce two different austenite grain sizes. In the coarse-grained specimen, hierarchical configurations of variants are formed and carefully analyzed using EBSD. These typical patterns result from the alternate formation of two perpendicular plate groups of variants over several length scales, and two distinct types of mechanical couplings are shown to occur sequentially in the process of the transformation of an austenitic grain. In the fine-grained specimen, the martensite start temperature is depressed below liquid nitrogen temperature, and the martensitic transformation can only occur under stress assistance. Grain size reduction brings about a dramatic change in the morphology of martensite and its configurations. Martensite is fully twinned, and martensite variants arrange themselves into self-accommodating configurations involving all four variants of the same plate group. Those specific configurations share striking similarities with those usually encountered in conventional shape memory alloys. The reversion of such microstructures upon heating is believed to be at the origin of the observed shape memory effect.

The titanium coated powder has shown promising results for in-situ microalloying. Hot cracking of the 7075 alloy was completely inhibited and grain refinement is massive. This effect is visible with and without preheating of the build plate. Mapping of the alloying elements has shown that precipitation at the grain boundaries is important, hence these elements require solution treatment to be available for precipitation hardening. The best yield strength achieved in this work was 376MPa.

This study demonstrates the usefulness of crystal plasticity modeling and crystallographic texture analysis when aiming to understand through-thickness strain heterogeneity after roll bonding of dissimilar materials. FE modeling was used at two length scales to study the deformation and texture heterogeneities inside a 9-layer multilaminate made of aluminum and steel, produced by roll-bonding. Microstructure and crystallographic texture were probed using EBSD. Numerical predictions indicated that plane strain compression was accompanied by significant shear parallel to the rolling plane and inclined shear banding in aluminum. Predictions of the Texture development were more accurate in the bcc phase than the fcc phase.

In this study, the influence of thermomechanical treatments on the microstructure and mechanical properties of a new metastable β-titanium Ti-23.6Nb-5.1Mo-6.7Zr alloy was assessed. The objective was to determine if the alloy is a potential candidate for a future fabrication of orthopedic implants, in particular prosthetic hip stems with a functional gradient of mechanical properties. Two thermomechanical processing routes were investigated: (a) 90% cold-rolled, (b) 90% cold-rolled, followed by annealing at 950°C for 1h. After these initial processing steps, samples were aged between 300°C and 500°C from 0.5h to 4h. Microstructural characterization was conducted by optical microscopy, transmission electron microscopy and x-ray diffraction. Young’s modulus and microhardness were measured. Young’s modulus of the sample annealed after cold rolling is lower than that after the cold rolled one. Aging was effective at increasing hardness but also increasing Young’s modulus. The hardening during aging resulted from fine ωiso and α precipitation. The transmission electron microscopy investigations indicated that an aging treatment at 500°C leads to a fine (α + β) microstructure, avoiding brittle ωiso precipitation. For these reasons, this alloy is a potential candidate for the manufacture of a hybrid hip prosthetic stem by employing localized aging treatment at 500°C in the neck region, creating a functional strength gradient and maintaining a low Young’s modulus in the distal part, which is needed to mitigate the stress shielding of the bone.

The printing of Fe-6.5wt%Si by LB-PBF is a complex process due to the formation of brittle phases during processing, which can lead to sensitivity to internal stresses. The paper shall show the issues encountered during processing and the resulting material, based on optical microscopy, defect analysis and classification. The manufacturing of thin walls has yielded better results than thick bulk material, and various laser melting strategies will be presented to demonstrate the trend between single and multiple meltpool thicknesses. The internal grain texture of the wall is obtained by means of EBSD. Furthermore, the magnetic hysteresis cycle of the printed material is measured using a vibrating magnetometer.

The potential bactericidal properties of nanosized zinc oxide (ZnO) make this semiconductor suitable for medical and pharmaceutical applications.In this article we present two methods of synthesis of ZnO nanoparticles (Nps-ZnO): chemical precipitation and solution combustion synthesis.The synthesized nanopowders were characterized with Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM).The EDS analysis indicate a Zn:O atomic ratio of 0.81 and 1.36, for the chemical precipitation and solution combustion synthesis, respectively.The XRD results confirm that Nps-ZnO obtained by both methods show a hexagonal arrangement (Wurtzite).TEM images show nanoparticles with mean diameters between 15.5 ± 6.8 nm and 73.4 ± 6.0 nm.Finally, the Kirby-Bauer disk diffusion method for the determination of antibacterial activity shows that Escherichia coli was more sensitive to the antimicrobial action of Nps-ZnO obtained by chemical precipitation than the Bacillus Subtilis bacteria.

Explaining the crystallography of iron alloys martensite with a {225}γ habit plane remains a challenging task within the phenomenological theory of martensite crystallography. The purpose of this study is to re-examine the martensite formed in a Fe-8Cr-1.1C alloy using EBSD, which has a better angular resolution than the conventional transmission electron diffraction techniques previously used. The results show that the single morphological plates, which hold a near {225}γ habit plane, are bivariant composites made up of two twin-related variants. It is shown that a {113}γ plane is systematically parallel to one of the three common 112α planes between the two twin-related crystals. This observation suggests that the lattice invariant strain of transformation occurs through a dislocation glide on the {113}γ ⟨110⟩γ system, rather than through twinning as is commonly accepted. Based on this assumption, the predictions of Bowles and Mackenzie’s original theory are in good agreement with the crystallographic features of {225}γ martensite. Unexpectedly, it is the high shear solution of the theory that gives the most accurate experimental predictions.

Superduplex stainless steels (SDSSs) have high mechanical and corrosion resistance. Those properties are due to the biphasic microstructure formed by ferrite and austenite in similar proportions. Oil and gas companies use a cold-worked seamless tube manufactured in SDSS in oil country tubular goods applications. However, the understanding of how the cold work influences the dislocation density in each one of the SDSS phases is unclear. In this work, a cold-worked SDSS W-alloyed was investigated. Samples in as-received condition (AR-CW) and solution thermal treated at 1050, 1100, and 1150 °C were analyzed using XRD. Additionally, the AR-CW sample was characterized in TEM. The dislocation density was measured using Williamson Smallman model, which uses the crystallite size and lattice microstrain as input parameters. Those parameters were calculated using different models: Scherrer; Monshi–Scherrer; and Williamson–Hall. The cold work promotes a smaller crystallite size and a bigger lattice microstrain. The thermal treatment reduces the levels of dislocation density, and the increase in the treatment temperature results in higher dislocation density.

The present paper aims at providing a fine-scale analysis of the Ti-4.5Al-2.5Fe-0.25Si α+α'+βretained microstructures to give insight into the link between the microstructural characteristics of the alloy (phase fraction and chemistry, grain size, etc.) and the deformation mechanisms at play. These microstructures were found to exhibit outstanding work-hardening capabilities that have the great potential to be obtained simultaneously with a high yield strength when the microstructural features are carefully optimized. Ex-situ analyses coupled with TEM revealed the simultaneous occurrence of Reorientation Induced Plasticity (RIP) into the self-accommodated Fe-enriched α' martensite, TRansformation Induced Plasticity (TRIP) of the βretained phase and TWinning Induced Plasticity (TWIP) of the α phase that add to dislocation glide. The Fe-enriched martensite has the remarkable capability to induce reorientation through two distinctive mechanisms: by the motion upon deformation of the intervariant boundary associated to the [45¯13¯]α′ Type II twin, a rather classical mechanism although not often reported into α'; but more surprisingly into such a fine phase, by the creation and growth upon deformation of {101¯2}1¯011α′ twins. A 3-scale mechanical contrast is proposed to explain the remarkable work-hardening rates achieved. Reorientation is shown to be a key microstructural feature for the development of Ti alloys with superior mechanical properties.

A new generation of titanium alloys with non-toxic, non-allergenic elements and lower Young’s modulus (YM) have been developed, presenting modulus values close to that of bone. In titanium alloys, the value of the Young’s modulus is strongly dependent on the chemical composition. Young’s modulus also depends on the present phases and on the crystallographic texture related to the thermomechanical processing. A lower YM is normally attributed to the formation of the α″ phase into the β matrix, but there is no consensus for this assumption. In the present work, four alloys were designed and melted, based on the Ti-Nb-Mo-Zr system and heat-treated to favor the formation of the β phase. The alloys were produced by arc melting under argon atmosphere and heat-treated at 1000 °C for 24 h under high vacuum, being subsequently quenched in water to room temperature. Alloys were then characterized by optical microscopy (OM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Young’s modulus was determined by the impulse excitation technique and Vickers microhardness. The purpose of the study was to define an optimal chemical composition for the further production on a semi-industrial scale of a new Ti-Nb-Mo-Zr alloy for orthopedic implant manufacturing. The results showed that all of the four studied alloys are potential candidates for biomedical applications. Among them, the Ti-24Nb-4Mo-6Zr alloy has the lowest Young’s modulus and the highest microhardness. So, this alloy presents the highest HV/YM ratio, which is a key indicator in order to evaluate the mechanical performance of metallic biomaterials for orthopedic implants.