Solute redistribution and phase stability at FeCr/TiO2− interfaces under ion irradiation

Abstract

Cr diffusion in trilayer thin films of 100 nm Fe-18Cr / 125 nm TiO 2-x / 100 nm Fe-18Cr deposited on MgO substrates at 500 °C was studied by either annealing at 500 °C or Ni 3+ ion irradiation at 500 °C. Microchemistry and microstructure evolution at the metal/oxide interfaces were investigated using (high-resolution) transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. Diffusion of Cr into the O-deficient TiO 2 layer, with negligible segregation to the FeCr/TiO 2-x interface itself, was observed under both annealing and irradiation. Cr diffusion into TiO 2-x was enhanced in ion-irradiated samples as compared to annealed. Irradiation-induced voids and amorphization of TiO 2-x was also observed. The experimental results are rationalized using first-principles calculations that suggest energetic preference for substituting Ti with Cr in sub-stoichiometric TiO 2. The

Cr incorporated phase transformation in Y2O3 under ion irradiation

“…2b1), the tendency of Cr to diffuse towards the interface is negligible. This is different from our previous FeCr/TiO 2−x studies, in which Cr diffused into the TiO 2−x layer during thermal annealing38. The EDS scan across the grain boundary in the FeCr layer uncovers a limited extent of Cr depletion at the boundaries (in Fig.…”

“…In real ODS steels, which contain a large number of alloying elements, radiation induced chemical redistribution will occur at the metal/Y 2 O 3 interface, which may significantly influence the evolution of the oxide phase. For example, our previous studies uncovered that the irradiation-induced incorporation of Cr in TiO 2 enhances the tendency of amorphization38 and, in MgO, causes the formation of MgCr 2 O 4 spinel39.…”

Irradiation-induced intermixing effects at the interfaces of titanium and titanium-dioxide thin films and Fe-12%Cr substrate

“…It is interesting to note that diffusion of Cr from a FeCr thin film into a TiO 2 thin film, after thermal exposure and irradiation with nickel ions at the same temperature (500ºC), has been already observed by Xu et al [25], where diffusion of Cr inside titania was correlated with the presence of an oxygen deficient phase of TiO 2-x . Our observations are consistent with these results.…”

“…However, irradiation and compositional stability studies at these oxide/matrix interfaces are challenging due to the small size of the oxide phase particles [14], their complex chemistry, and the differing affinities of oxygen to the various metallic constituents of the alloy, which might play an important factor in the changes in the microstructure and microchemistry at the metal/oxide interface [23]. Therefore, in order to reduce the complexity of the analysis, ideal 2-D emulations, with a simplified chemistry, can be performed by synthetizing thin film bilayer or multilayer composite and used as model systems for studies concerning radiation response of solid interfaces [24,25].…”

Asymmetric interaction of point defects and heterophase interfaces in ZrN/TaN multilayered nanofilms

“…The preferential amorphization of the oxides dispersed in ODS steel was often triggered by ion radiation because the oxides acted as effective sinks for trapping point defects404142. Therefore, it is reasonable to believe that the asymmetric interaction of point defects and heterophase interfaces has a significant impact on the microstructure evolution of the radiation tolerant materials.…”