Metallurgical characterisation of modi® ed F ± 82H steel was carried out. Microstructural studies together with mechanical testing were conducted on the steel in the as received state and after thermal aging in the temperature range 300 ± 600°C for periods up to 5000 h. In addition, precipitate development during creep tests at 600 and 650°C was studied. During thermal aging, the general microstructure of the steel (tempered martensite with M 23 C 6 precipitates) remained stable up to 500°C. However, at 550 and 600°C, in addition to the M 23 C 6 carbides, Laves phase and precipitates with intermediate composition between carbides and Laves phase were observed. In terms of mechanical properties, the F ± 82H modi® ed steel exhibited the same values of hardness, ultimate tensile stress and 0 . 2% proof stress, and similar creep rupture strength, regardless of the material condition studied. In contrast, aging treatments at 550 and 600°C caused a signi® cant decrease in impact properties, essentially attributable to the Laves phase precipitation.MST/5107

No abstract

No abstract

Advances in computational capability and modeling techniques, as well as improvements in experimental characterization methods offer the possibility of directly comparing modeling and experiment investigations of irradiation effects in metals. As part of a collaboration among the Instituto de Fusión Nuclear (DENIM), Lawrence Livermore National Laboratory (LLNL) and CIEMAT, single and polycrystalline α-Fe samples have been irradiated with 150 keV Fe- ions to doses up to several dpa. The irradiated microstructure is to be examined with both transmission electron microscopy (TEM) and positron annihilation spectroscopy (PAS). Concurrently, we have modeled the damage accumulation in Fe under these irradiation conditions using a combination of molecular dynamics (MD) and kinetic Monte Carlo (KMC). We aim to make direct comparison between the simulation results and the experiments by simulating TEM images and estimating positron lifetimes for the predicted microstructures. While the identity of the matrix defect features cannot be determined from TEM observations alone, we propose that both large self-interstitial loops, trapped at impurities within the material, and small, spherical nanovoids form.