Quenching and Partitioning (Q&P) steels are promising candidates for automotive applications because of their lightweight potential. Their properties depend on carbon enrichment in austenite which, in turn, is strongly influenced by carbide precipitation in martensite during quenching and partitioning treatment. In this paper, by coupling in situ High Energy X-Ray Diffraction (HEXRD) experiments and Transmission Electron Microscopy (TEM), we give some clarification regarding the precipitation process of iron carbides in martensite throughout the Q&P process. For the first time, precipitation kinetics was followed in real time. It was shown that precipitation starts during the reheating sequence for the steel studied. Surprisingly, the precipitated fraction remains stable all along the partitioning step at 400 °C. Furthermore, the analyses enable the conclusion that the iron carbides are most probably eta carbides. The presence of cementite was ruled out, while the presence of several epsilon carbides cannot be strictly excluded.

Al-Ti-B master alloys are widely used in the aluminum industry as grain refiners for the control of the microstructure of the aluminum alloys. The SHS (self-propagating high-temperature synthesis) is an ex situ method that uses exothermic reactions to sustain the chemical reaction in a combustion wave. The advantages of SHS are the low energy requirement, simplicity and product purity. However, the raw material used has to be very pure, with a very small size leading to the necessity of a reactor with a protective gas to produce the reaction. The purpose of this investigation is to fabricate SHS master alloys with commercial standard raw materials, with lower purity and higher grain size without a reactor or protective gas in order to (1) decrease the price and (2) improve the productivity of master alloy manufacturing. The possibility of using cheap borated salts instead of expensive pure boron has been studied. Different compositions of aluminum master alloy have been developed. Bigger TiB₂ grain size has been obtained when using bigger commercial raw materials. Larger titanium powder can produce an aluminum master alloy with a maximum of 30% of aluminum without reactor. In comparison, SHS reaction is much more difficult when using finer titanium powder.

Resistance upset welding is successfully applied to Oxide Dispersion Strengthened (ODS) steel fuel cladding. Due to the strong correlation between the mechanical properties and the microstructure of the ODS steel, this study focuses on the consequences of the welding process on the metallurgical state of the PM2000 ODS steel. A range of process parameters is identified to achieve operative welding. Characterizations of the microstructure are correlated to measurements recorded during the welding process. The thinness of the clad is responsible for a thermal unbalance, leading to a higher temperature reached. Its deformation is important and may lead to a lack of joining between the faying surfaces located on the outer part of the join which can be avoided by increasing the dissipated energy or by limiting the clad stick-out. The deformation and the temperature reached trigger a recrystallization phenomenon in the welded area, usually combined with a modification of the yttrium dispersion, i.e., oxide dispersion, which can damage the long-life resistance of the fuel cladding. The process parameters are optimized to limit the deformation of the clad, preventing the compactness defect and the modification of the nanoscale oxide dispersion.

Nanocrystalline diamond NCD coatings could improve the performances of cutting tools if the adhesion on cobalt-cemented tungsten carbide WC–Co substrates was optimized and maintained during diamond deposit. In this study, a time modulated polarized growth process during diamond hot filament chemical vapor deposition (HFCVD) method was used. NCD coatings were deposited on cobalt-cemented tungsten carbide (WC–10% Co) substrates previously coated with tantalum or zirconium nitride–molybdenum bilayer as interlayer systems to control carbon and cobalt diffusion. Continuous films consisted of diamond clusters. Their size decreased when the applied bias voltage increased and substrate temperature decreased. Raman analyses confirmed the reduction of crystallite size and formation of nanocrystalline diamond films by time modulated biased substrate HFCVD process. Scratch tests showed that the NCD/interlayer systems/WC–10% Co displayed very good film adhesion interesting for cutting tools applications compared to NCD/WC–10% Co. In addition using an interlayer system could offer additional protection when diamond coating was deteriorated. This technique seems to be promising for industrial applications in the field of machining tools when increasing the thickness of the diamond layer by only extending the time modulated deposition process.

To address the limited biocompatibility of conventional removable dental prostheses (RDPs), new materials and manufacturing techniques are being actively investigated. This in vitro study aimed to evaluate and compare the biological response of human fibroblast (HGF) to cobalt-chrome (Co-Cr), titanium alloy (Ti), and polyetheretherketone (PEEK), fabricated via tree distinct methods: casting, selective laser melting (SLM) and machining. The surface chemical composition and the wettability of cast Co-Cr, SLM Co-Cr, SLM Ti, machined Ti, and PEEK were assessed. HGF were cultured in contact with material extracts, and all assays were conducted following this exposure. Ion release was assessed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and pH measurement. Surface roughness was subsequently measured on each sample. Cell viability was assessed using the Live/Dead staining, while metabolic activity was evaluated using the Alamar Blue assay. Cell morphology was observed by scanning electron microscopy (SEM) and confocal microscopy, while inflammatory profile was assessed using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using one-way ANOVA and Tukey's test (p < 0.05 and 0.001). SLM Co-Cr exhibited higher Co and Cr surface content than cast Co-Cr, while SLM Ti showed a reduced titanium content and increased aluminum content relative to machined Ti. Among all tested materials, machined Ti demonstrated the highest surface wettability, evidenced by a significantly lower contact angle (p < 0.001). HGF exposed to extracts of machined Ti and PEEK exhibited greater cell viability and metabolic activity, comparable to the control group. In contrast, cast Co-Cr was associated with significantly increased IL-6 secretion, although TNF-α and IL-10 levels remained stable across tested groups. Machined titanium (Ti) and PEEK exhibited favorable in vitro biocompatibility, with high cell viability, enhanced cellular adhesion, and no significant cytotoxicity under our experimental conditions. These findings suggest that both materials may represent promising alternatives to CoCr alloys for the fabrication of removable partial dentures, although their clinical application requires further validation of their mechanical, physical, and long-term properties.