Solute clusters damage

Fe or Ni ion irradiation with energies of a few MeV is mostly used for studies of radiation damage of RPV steels. Previous studies have provided information on the effects of Cu, Mn and other elements, carbides, dose rate and tensile stress on hardness, matrix damage evolution and solute cluster formation in model alloys and commercial steels (e.g. Fujii and Fukuya, 2005 Murakami et al., 2009). These data provide clear evidence of the effects of various metallurgical parameters on hardening and microstructural evolution in Fe-based alloys and RPV steels, although these data cannot be directly or quantitatively correlated to data from neutron-irradiated materials. 

Van Ouytsel et demonstrated that IF measurements are sensitive to long- and short-range damage mechanisms and that the results are consistent with results obtained from impact, tensile and hardness testing. In particular, the decrease in the IF with irradiation in RPV steels can be related to observations of precipitation of solute clusters. 

In Section 9.13 we focus on the mechanistic framework that incorporates insight into matrix damage and solute clusters... 

The insight developed into the mechanisms of controlling matrix damage formation and solute clustering have led to the adoption of a simple mechanistic framework that underpins the development of dose-damage... 

It is important to note that we assume the random fracture approximation (RPA) is applicable. This assumption has certain implications, the most important of which is that it bypasses the real evolutionary details of the highly complex process of the lattice bond stress distribution a) creating bond rupture events, which influence other bond rupture events, redistribution of 0(microvoid formation, propagation, coalescence, etc., and finally, macroscopic failure. We have made real lattice fracture calculations by computer simulations but typically, the lattice size is not large enough to be within percolation criteria before the calculations become excessive. However, the fractal nature of the distributed damage clusters is always evident and the RPA, while providing an easy solution to an extremely complex process, remains physically realistic. 

In more recent optical extinction measurements on specially filtered samples [60], the weak bump had disappeared. This bump may thus have been due to damaged clusters (see Sect. 3.6) or cluster aggregates which form colloidal inclusions in the sample. The main feature of the UV-visible spectrum of AU55 in solution is then a broad absorption extending across the whole visible region. 

Nearly all modifications that have been detected on the model level (Chap. 10) are also found in free-radical damaged DNA. Obviously the DNA-bound lesions are much more difficult to detect, and there is an ongoing discussion as to the best procedure of their excision (Chap. 13.2 for a review on the excision and repair of base lesions in vivo see Wallace, 2002). Mechanistic details concerning the formation of the base lesions have been discussed in Chapters 10 and 11, and only some additional information will be given below and in the section on clustered lesions where the phenomenon of tandem lesions, two damaged bases that are formed side by side, is dealt with. The yields of damaged bases formed upon y-irradiation in aqueous solution, as has been determined by the GC-MS/SIM technique, are compiled in Table 12.5. 

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