Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of the Effect of Mn on the Nanostructural Features formed in Irradiated Fe-Cu-Mn Alloys.

Glade, S. C. ; Wirth, B. D. ; Asoka-Kumar, P. ; Odette, G. R. ; Sterne, P. A. ; Howell, R. H.

Technical Information Center Oak Ridge Tennessee

关键词: Positron annihilation;    Neutron scattering;    Small angle scattering;    Meetings;    Irradiation;   

RP-ID  :  DE200415007746

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The size, number density and composition of the nanometer defects responsible for the hardening and embrittlement in irradiated Fe-0.9wt.% Cu and Fe-0.9wt.% Cu-1.0wt% Mn model reactor pressure vessel alloys were measured using small angle neutron scattering and positron annihilation spectroscopy. These alloys were irradiated at 290 C to relatively low neutron fluences (E> 1 MeV, 6.0 x 10(sup 20) to 4.0 x 10(sup 21) n/m(sup 2)) in order to study the effect of manganese on the nucleation and growth of copper rich precipitates and secondary defect features. Copper rich precipitates were present in both alloys following irradiation. The Fe-Cu-Mn alloy had smaller precipitates and a larger number density of precipitates, suggesting Mn segregation at the iron matrix-precipitate interface which reduces the interfacial energy and in turn the driving force for coarsening. Mn also retards the precipitation kinetics and inhibits large vacancy cluster formation, suggesting a strong Mn-vacancy interaction which reduces radiation enhanced diffusion.