Oxidation and oxygen diffusion in Ti-6al-4V alloy: improving measurements during sims analysis by rotating the sample

Titanium alloys are attractive to the industrial world, as they offer the benefits of low density, great corrosion resistance, and relatively good strength, making them viable candidates for a multitude of applications. However, above 500 °C, oxidation and oxygen diffusion in titanium alloys need to be taken into account as they change their microstructure and then their mechanical properties. Oxidations were carried out between 600 and 750 °C on a specific titanium alloy: an a-b annealed Ti-6Al-4V. Oxidation kinetics and oxygen diffusion in the matrix were studied. SIMS analyses were realized on rotating specimens of this two-phase polycrystalline alloy in order to reduce roughness. Composition profiles along the sample thickness were compared to microhardness measurements. SIMS mappings were realized on the smooth slopes of the crater

Elaboration and characterization of thin solid films containing cerium

AbstractCerium oxide films are widely studied as a promising alternative to Cr(VI) based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electrodeposition of Cerium containing thin films was realised on TA6V substrates from a Ce(NO3)3, 6H2O and mixed water–ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity appears proportional to the quantity of electricity used, as indicated by the Faraday law. Subsequent thermal treatment lead to a CeO2 coating, expected to provide an increase of TA6V oxidation resistance at high temperatures. The deposits were characterized by differential scanning calorimetry (DSC), optical and scanning electron microscopies

On dipping of γ-TiAl in low-concentration phosphoric acid solution and consecutive oxidation resistance at 800 °C

The oxidation behaviour of γ-TiAl previously treated in low-concentration phosphoric acid solution has been investigated at 800 °C in air. The chemical treatment promotes, instead of the usual TiO2/Al2O3 mixed phase, the fast formation of a TiP2O7 pyrophosphate layer with a subsequent large reduction in the oxidation rate. © 2006 Acta Materialia Inc

On the relation between damage rate and stress level evolution in α-Cr2O3 thin films growing on Ni-33at%Cr

The blistering phenomenon has been studied in chromia films formed between 700 and 900 °C on Ni-33at%Cr. The experimental conditions of the blister occurrence and the damaged surface by blisters and spalls have been determined. From the comparison between the growth stress evolution in the oxide film - which has been related to the oxide microstructure development - and the damage rate the stress relaxation by creep is shown to prevent the formation of blisters and spalls. © 2009 Elsevier Ltd. All rights reserved