À la fin du XVIIIe siècle, le pianoforte a progressivement supplanté le clavecin. Au cours de la première moitié du XIXe siècle, les fabricants de pianos ont utilisé des cordes de plus en plus résistantes, souhaitant rendre les instruments plus puissants afin d’être joués dans des salles de concert plus grandes et de répondre à la demande musicale et culturelle de la société européenne. Si les modifications apportées à l’instrument lui-même sont bien connues, peu d'études ont été réalisées sur les cordes à piano historiques en fer et en acier, bien que des procédés métallurgiques innovants aient été mis en œuvre au cours de cette période. Les analyses et les observations de 148 cordes ont montré qu’avant 1825-1830, elles présentent une teneur élevée en phosphore, alors qu’après cette date, les aciers phosphoreux laissent place à des aciers à cémentite globulaires d’une teneur en carbone encore assez faible, exempt de phosphore mais contenant du manganèse. Après 1850 des cordes en acier à plus haute teneur en carbone et tréfilées à chaud apparaissent.

Sulfur addition to zirconium alloys is known to have a tremendous strengthening effect, with only a few ppm leading to a strong hardening and a noticeable decrease of the creep rate above 300°C. Although previous works have shown an interdependent effect of oxygen and sulfur, with sulfur amplifying the strengthening of oxygen in the domain of dynamic strain aging, the physical mechanism behind this impact of sulfur addition on zirconium mechanical properties is still unknown. Using in situ straining experiments in a transmission electron microscope, we study how sulfur and oxygen modify the glide motion of dislocations for temperatures between 200°C and 550°C in zirconium samples with an oxygen concentration between 80 and 1300 weight ppm and a sulfur concentration up to 25 wppm. These experiments show that the velocity of gliding dislocations is reduced by the dragging of their enriched oxygen atmosphere, when the temperature is high enough for oxygen to diffuse and segregate on dislocations. Once the motion of dislocations is slowed down, segregation of sulfur on dislocations becomes also possible despite the low sulfur content, leading to a further reduction of dislocation velocity. This synergistic effect of sulfur and oxygen segregation on dislocation explains the enhancement by sulfur of oxygen strengthening in zirconium alloys.

Thin native oxide films spontaneously formed on a series of cobalt-nickel alloys with varying cobalt concentrations were investigated using X-ray photoemission spectroscopy (XPS). Combining XPS with sequential ion abrasion allowed identification of the various oxides and hydroxides present within the passive layers, depending on their depth in the films, which do not exceed 5 nm. A recent study of the Co20Ni80 alloy showed that the surface layer is heterogeneous both laterally and in depth, with some regions covered by oxidized cobalt compounds and others by oxidized nickel compounds. Different oxide thicknesses were observed on the Co20Ni80 alloy compared to pure Ni and Co metals. In the present study, we investigate the thicknesses and compositions of cobalt and nickel oxide films in binary alloys Co x Ni100-x , with x = 0, 20, 50, 70, 90, and 100. Building on the previous study of Co20Ni80, where a surface galvanic effect induced by alloying was proposed, we show that variations in Co concentration suggest that the magnetic properties of the substrate influence the composition of the passivation layers formed on the cobalt-nickel alloys.

XPS data processing for cobalt and nickel core-level peaks can be complicated. This is especially true when analyzing a mixture of oxide/oxyhydroxide/hydroxide compounds of these metals. The objective of this study is to develop a method for decomposing XPS spectra of 2p core levels for nickel and cobalt-oxidized compounds. This methodology was then employed to study the passivation layer of the Co20Ni80 alloy. The analysis of Ni2p and Co2p photo peaks using a homemade code based on core-level peak structure and satellites enables us to determine the chemical composition of the surface layer, knowledge of which is particularly important because it is directly linked to the anticorrosive properties it confers on the surface of the oxidized alloy. The XPS analysis, coupled with sequential ion sputtering, revealed that the passive layer of the Co20Ni80 alloy is heterogeneously covered with either oxidized cobalt compounds or oxidized nickel compounds. The method used also demonstrates that the chemical heterogeneity is associated with the thickness heterogeneity of the passive layer.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with deuterium labelling (D2O), and X-ray photoelectron spectroscopy (XPS) were applied to investigate the interfacial transport mechanisms of hydroxyls between aqueous electrolyte and outer part of the protective oxide film during passivation of Cr15Fe10Co5Ni60Mo10 multi-principal element alloy surfaces. A ToF-SIMS signal treatment methodology was developed to retrieve the in-depth distribution of deuterated hydroxides in the nanometer-thick surface oxide film. After immersion at free potential or anodic passivation in acidified D2O, the initial bilayer structure is retained. The use of heavy water electrolyte has no effect on the composition alterations induced by passivation. Deuterated species were detected mostly in the outer layer of the surface oxide film. Pure inward hydroxyl diffusion from electrolyte/oxide to oxide/metal interface is excluded from being primarily responsible for oxide film growth induced by anodic passivation. The hydroxyls from the dissolving hydroxide species are retained in the oxide film and participate in forming Cr hydroxide, thus reducing the hydroxyl surface uptake from the electrolyte. This work provides deeper insight into the mechanisms of oxide growth and corrosion protection induced by anodic passivation.

The fire at Notre-Dame de Paris led to the discovery of several series of previously unknown iron armatures, which were systematically recorded. Amongst them, several iron staples from the top of the eaves walls, lead crest reinforcements and a sample of the tie rods used in the choir in the 19th century were analysed by metallography and tensile tests in order to determine their nature and mechanical characteristics. These results can be put into perspective with previous studies on such monuments. The chemical analysis with SEM-EDS of the slag inclusions contained in the matrix of these ferrous alloys makes it possible to determine the technical processes used for their production throughout the construction and restoration of the building, highlighting several differences depending on the typologies of the iron armatures. This information is complemented by a series of radiocarbon dates currently being carried out to better understand the periods of use of these ferrous reinforcements. When compared with those of other materials, these dates could be used to recalibrate the phasing of the building.

Variations with oxygen concentration of titanium lattice parameters are obtained by means of ab initio calculations, considering the impact of oxygen ordering. The quasiharmonic approximation is used to take into account the thermal expansion at finite temperature. Results show that lattice parameters depend mainly on oxygen concentration and, to a lesser extent, on the ordering state. Knowing these theoretical variations, one can get insights into the composition of ordered compounds existing in Ti-O binary alloys from their lattice mismatch measured experimentally by x-ray diffraction. The approach is used in a binary alloy containing 6000 ppm in weight of oxygen. It is concluded that the ordered compounds, which are observed after a recrystallization heat treatment, do not have the expected Ti6O stoichiometry but have a composition close to the nominal concentration. Oxygen ordering proceeds, therefore, before oxygen partitioning in titanium.

In the context of the heat treatment optimisation of steels used for nuclear reactor pressure vessel, the carbide precipitations in three model alloys: Fe-0.2 %C-1 %Mn, Fe-0.2 %C-1.5 %Mo and Fe-0.2 %C-1 %Mn-1.5 %Mo have been experimentally investigated and modelled. The precipitation sequences for times up to 2 months at 650 and 700 degrees C have been determined Fe-0.2 C-1.5Mn: cementite only Fe-0.2 C-1 Mo: cementite -> cementite + M2C -> M2C + xi carbide Fe-0.2 C-1 Mo-1.5 Mn: cementite -> cementite + M2C + xi carbide The volume fractions in carbide were determined by Rietveld refinement of synchrotron X-ray diffractograms. This characterisation has confirmed the tendency for cementite dissolution in favour of other Mo rich carbides in Mo containing alloys. Similarly, PRISMA modelling of the carbide volume fractions predicts a tendency for cementite dissolution in Mo containing alloys. It has also enabled the relative contribution of some of the factors affecting xi carbide precipitation to be understood.

The study of iron reinforcements used in the construction of Notre-Dame de Paris offers a glimpse into the innovation that took place on this building site in the mid-12th century, adapting metal to create a novel architecture. The restoration of the monument after the 2019 fire offered unique possibilities to investigate its iron armatures and to sample 12 iron staples from different locations (tribunes, nave aisles and upper walls). Six of them were dated thanks to the development of an innovative methodology based on radiocarbon dating. They reveal that Notre-Dame is the first known Gothic cathedral where iron was massively used as a proper construction material to bind stones throughout its entire construction, leading to a better understanding of the master masons' thinking. Moreover, a metallographic study and slag inclusion chemical analyses of the staples provide the first study of iron supply for a great medieval Parisian building yard, renewing our understanding of iron circulation, trade and forging in the 12th and 13th century capital of the French kingdom. The highlighting of numerous welds in all iron staples and the multiple provenances sheds light on the activity of the iron market in this major medieval European city and the nature of the goods that circulated, and questions the possible importance of recycling.

Surface analysis by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry was applied to investigate the origin of the enhanced surface passivity and resistance to a chloride-induced breakdown provided by the protective ultrathin oxide films formed on Cr–Fe–Co–Ni–Mo single-phase fcc multi-principal element alloys. A bilayer structure of the oxide films is observed with the inner barrier layer mostly constituted of Cr(III) oxide and the outer layer enriched in Cr(III) hydroxides and Mo(IV,VI) oxides. The Mo(VI) and Mo(IV) species are mainly located in the outer and inner parts of the outer layer, respectively. Anodic passivation promotes mainly the growth of the inner layer on the alloy of higher Cr bulk content and the outer layer on the alloy of higher Mo bulk content. Passivation also promotes the enrichment of Cr(III) hydroxide and Mo(IV) and Mo(VI) oxides in the outer layer. Depth distribution analysis suggests that the ultra-thin protective inner barrier contains Cr(III)-depleted heterogeneities acting as weak sites for chloride attack, which are reinforced by the Mo(IV) oxide species concentrated close to the inner barrier layer. This elemental distribution provides an explanation for the reinforcement of the resistance to localized corrosion observed on these Cr–Fe–Co–Ni–Mo alloys.

The paper aims at understanding the nature of ferrous alloys used for the fabrication of Renaissance armour in a Nuremberg workshop, owned by Valentin Siebenbürger. Noninvasive techniques such as X-ray diffraction (XRD) using synchrotron radiation (SR) are well suited to identify the different crystalline phases, characteristic of ancient ferrous alloys, avoiding multiple sampling, rarely allowed in the case of museum pieces. However, such experiment presented analytical challenge due to the complex shape of armours. Our goal was to demonstrate the feasibility of SR-XRD measurement to identify mineral phases contained in ferrous alloys (cementite, ferrite, martensite …) on large and complete museum amour pieces and provide new insights on Renaissance armour manufacturing. The study allowed identifying phases characteristic of ancient ferrous alloys (ferrite, cementite …) but also the presence of heat treatment, on some armour plates, giving new information on manufacturing technique and workshop organization.

Oxygen content has always been limited in commercial titanium and titanium alloys due to its propensity to induce a severe ductility loss. Yet, its effect on the macroscopical behavior has never been clearly understood and is still rather unclear considering the wide variability in the literature results. Here, we investigate the tensile properties of alpha-titanium with oxygen contents ranging from 0.15 to 0.80 weight percent (wt%). While the strain-hardening ability of oxygen is maintained, no ductility drop is observed up to 0.60 wt% of oxygen, thus allowing exceptional combinations of mechanical properties with an ultimate tensile strength (UTS) of 800 MPa and 29% of elongation at fracture for the Ti-0.6O alloy. Both high strength and ductility of these alloys result from the dislocations/precipitate's interactions. It is proposed that these interactions induce an important cross-slip ac-tivity responsible for a dislocation multiplication and a high work-hardening rate. With the addition of Zr, alloys exhibit an even more promising combination of mechanical properties, achieving 1,075 MPa of UTS and 28% of elongation at fracture for the Ti-4.5Zr-0.8O alloy. The mechanical properties of TiO and TiZrO alloys brought out in this study surpass those of Ti-6Al-4V alloy and open significant prospects for developing a new generation of oxygen-tolerant titanium alloys.

In this study, we report the experimental coarsening kinetics at 850, 900 and 950 degrees C of four complex concentrated alloys in the Al-Ti-Cr-Fe-Co-Ni senary system with different chemical compositions but a similar gamma' (L1(2)) volume fraction (similar to 35 % at 950 degrees C) in a face-centered cubic (gamma, FCC) matrix. The selected alloys were specifically designed to investigate the influence of Fe additions and Ni-Co substitutions on Ostwald ripening kinetics. Atom Probe tomography (APT) was used to determine the compositions of the FCC and L1(2) phases, which agree very well with Calphad calculations at thermodynamic equilibrium. Thermo-kinetic modeling of L1(2) precipitation was carried out using the Prisma module developed by Thermo-Calc and compared with experimental results. Apparent activation energies were determined and discussed in light of diffusion-controlled coarsening models to identify the key parameters affecting Ostwald ripening. We suggest that the abnormally high apparent activation energies results from composition-dependent parameters. When the latter are accounted for, the corrected activation energies for coarsening are in better agreement with available diffusion data.

The composition and stratification of the passive oxide films formed on three Cr-Fe-Co-Ni(-Mo) multi-principal element alloys by electrochemical anodic passivation in sulfuric acid electrolyte containing 0.2 and 4.7 M NaCl were investigated, combining X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry surface analysis. The passive films show a bilayer structure similar to that formed in Cl − -free electrolyte with an inner layer mostly consisting of Cr oxide and an outer layer containing of Cr hydroxide, Ni hydroxide, Mo oxides, and Fe (hydr)oxide. The Mo-free alloy exhibits a thickening of the inner Cr oxide layer and the thinning of the outer layer in 0.2 M Cl − , whereas the two Mo-containing alloys do not show significant alteration even in 4.7 M Cl − evidencing their higher stability in Cl − -containing solutions. The chloride penetration is limited to the external part of the outer oxide layer, except in the most severe tested conditions where traces reach the inner barrier layer, and the chloride entry into the layer is strongly reduced after pre-passivation in Cl − -free solution. The results allow us to discuss the beneficial effects of pre-passivation in Cl − -free conditions and Mo addition providing these alloys enhanced resistance to passivity breakdown.

X‐ray photoelectron spectroscopy analysis was applied to investigate the thermal stability under ultra‐high vacuum environment of the surface oxide film formed by electrochemical passivation of a newly designed Cr 15 Fe 10 Co 5 Ni 60 Mo 10 (at.%) multi‐principal element alloy and providing the alloy superior localized corrosion resistance compared to conventional stainless steels and alloys. A spectral decomposition methodology involving the subtraction of Auger peaks overlapping the Fe 2p and Co 2p core level regions was applied for quantification of the oxide film composition and thickness. The results show that, at 100°C, the passive oxide film is mainly dehydrated and dehydroxylated. Obvious loss of Ni hydroxide and conversion of Mo (VI) to Mo (IV) species are observed at 200°C, with further reduction of Mo species to Mo (III) observed at 300°C. In this temperature range, the total cation quantity in the oxide film remains stable despite the compositional alteration. At 400°C, Cr (III) oxide forms at the expense of Fe and Mo oxides, resulting in an oxide film essentially consisting of chromium oxide. At 500°C, Cr (III) oxide is eliminated, making the passive film unstable at this temperature. Possible Cr oxide removal mechanisms are discussed.

Significant research efforts have been undertaken over the past forty years to replace the StelliteTM cobalt-based alloys, which boast outstanding performances when used as hardfacing coatings, but proved problematic especially in radioactive environments. This work's purpose is to contribute to this effort by coming up with viable substitutes made of Complex Concentrated Alloys (CCAs). Previous work evidenced the (CrFeNi)90Mo5Ti5 alloy as a promising base that relies on the formation of intermetallic phases within a ductile matrix for an increase in hardness and an improved tribological behaviour. In this particular framework, the in situ alloying capabilities of the DED (Direct Energy Deposition) process were used for further explorations around this composition. Compositionally graded samples were successfully made despite the especially high brittleness of the alloys of interest. Coupled with an extensive use of the CALPHAD method, this combinatorial strategy dramatically speeds up material development compared to what the more conventional ways can achieve. The present paper emphasizes on the methodology and the high-throughput tools that were developed and used in this study, as such elements are growing in importance in the current context of intensive global research for new materials, especially in the CCAs field.

Generally, in metallic alloys, attaining ultra-fine sub-micron grain sizes by recrystallisation requires severe plastic deformation (SPD), however SPD techniques are difficult to apply to large quantities of material. In this work, we explore a strategy to reach an ultra-fine grained microstructure in a metastable-beta titanium Ti-20Nb-6Zr (at.%) by controlled recrystallisation after conventional rolling and annealing. The thermally stable sub-micronic dual phase microstructures are associated with the formation of strain-induced martensite during rolling and its subsequent reversion during annealing. Some specimens were cold-rolled to change most of the beta microstructure to stress-induced martensite (SIM); others were "warm rolled" just above the critical temperature for formation of SIM (453 K). The role of SIM in grain refinement was isolated by comparing the microstructural evolution of the two sets of specimens during annealing treatments. The cold rolled specimens produced an effective ultrafine grain recrystallisation, which was identified to start from 723 K, and a final equiaxed alpha-beta microstructure of ~250 nm. In warm rolled specimens without SIM, no new beta grains were observed, only an array of intragranular acicular alpha precipitates of approximately 50 nm thickness.