Atom Probe Sample Preparation

International audienc

Atom Probe Sample Preparation

International audienc

In-situ transmission electron microscopy investigation of the influence of hydrogen on the oxidation mechanisms of fine grained magnesium

International audienceMagnesium oxide is of critical importance for the properties of magnesium alloys designed for solid state storage of hydrogen. The oxidation of Mg was investigated by in-situ transmission electron microscopy under vacuum conditions and 105 Pa of H2 with a special emphasis on the influence of grain boundaries. In agreement with thermodynamic predictions, nucleation and growth of MgO was observed in both conditions, but the mechanisms and the corresponding kinetic are very different. Under vacuum it is assisted by Mg sublimation and relatively fast, while under H2 the oxidation proceeds slowly along grain boundaries that act as nucleation sites

Nanoscale characterization and formation mechanism of nanoclusters in an ODS steel elaborated by reactive-inspired ball-milling and annealing

International audienceReactive-inspired ball-milling is proposed as a new production route for oxide dispersion strengthened (ODS) steels. So a Fe–14Cr–2W–1Ti–0.8Y–0.2O (wt.%) ODS steel is elaborated by ball-milling of FeCrWTi and YFe3 plus Fe2O3 powders instead of Y2O3 and then by annealing at 800 °C for 5 min. Characterizations by Electron Probe MicroAnalysis and Atom Probe Tomography (APT) are performed after milling and after annealing. For the very first time, nanoclusters are observed after ball-milling by APT. Those nanoclusters are enriched in titanium, yttrium and oxygen and their mean radius is 0.8 nm. With annealing, the mean radius rises up to 1.4 nm and the number density as well as the enrichment factor in O, Ti and Y increase. So a new formation mechanism of nanoclusters is observed in those conditions of synthesis: ball-milling initiates the nanoclusters nucleation and during annealing, nucleation continues, accompanied by a slight growth of nanoclusters. Thus reactive-inspired ball-milling appears as a promising route for synthesizing ODS steels with a fine and dense dispersion of oxides

Effect of neutron-irradiation on the microstructure of a Fe–12at.%Cr alloy

International audienceA nanoscale description of the microstructure in a Fe–12at%Cr model alloy of low purity which has been neutron irradiated at 300°C up to 0.6 dpa, has been performed owing to atom probe tomography (APT). APT investigations have shown that the impurities are also involved in the microstructural evolution under irradiation. Two different populations of clusters have been observed: Cr-enriched and NiSiPCr-enriched clusters. As expected with a process of enhanced precipitation, Cr-enriched clusters are homogeneously distributed inside grains and certainly not correlated to dislocation loops. The NiSiPCr-enriched clusters, which are probably radiation induced segregations, are independent of the Cr-enriched clusters and are also homogeneously distributed. A quantitative description of these objects is presented in this paper and results are compared to SANS data of the literature obtained for the same model alloy

Degradation of Au–Ti contacts of SiGe HBTs during electromagnetic field stress

International audienc

In-situ transmission electron microscopy investigation of the influence of hydrogen on the oxidation mechanisms of fine grained magnesium

International audienceMagnesium oxide is of critical importance for the properties of magnesium alloys designed for solid state storage of hydrogen. The oxidation of Mg was investigated by in-situ transmission electron microscopy under vacuum conditions and 105 Pa of H2 with a special emphasis on the influence of grain boundaries. In agreement with thermodynamic predictions, nucleation and growth of MgO was observed in both conditions, but the mechanisms and the corresponding kinetic are very different. Under vacuum it is assisted by Mg sublimation and relatively fast, while under H2 the oxidation proceeds slowly along grain boundaries that act as nucleation sites

Degradation of Au–Ti contacts of SiGe HBTs during electromagnetic field stress

International audienc

Precipitation Kinetics in a Nb‐stabilized Ferritic Stainless Steel

International audienceno abstrac

Robustness of 4H-SiC 1200V Schottky diodes under high electrostatic discharge like human body model stresses : An in-depth failure analysis

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