SMALL-ANGLE NEUTRON-SCATTERING STUDY OF DEFECT CLUSTERS AND PRECIPITATES IN METALLIC ALLOYS

This article summarizes the principles of the small-angle neutron scat tering technique, and presents some examples of application: character ization of defect clusters in neutron-irradiated ferritic steels, of c opper-rich precipitates in electron-irradiated iron-based alloys and o f the gamma' precipitates in quenched industrial superalloys. In the c ase of ferromagnetic alloys, one emphasizes the specific information b rought by experiments performed under magnetic field. Our studies show that the defects responsible for radiation-induced embrittlement of p ressurized-water nuclear reactors are nanosized clusters consisting ma inly of copper precipitates or impurity-point defect clusters dependin g on whether the residual copper content of the steel is larger or sma ller than 0.1%.