Cross-section specimen preparation technique for nickel alloys and stainless steels

Abstract

Ion-irradiation studies are often used to gain insights into the response of metals to intense neutron environments. Transmission electron microscopy allows the microstructural effects of the irradiation to be studied. When transverse specimen preparation techniques are employed, the entire irradiated region may be viewed in the electron microscope due to the limited range of the incident ions. One technique for the preparation of cross-section TEM specimens is presented. A reliable and repeatable procedure for electroplating nickel on nickel- and iron-based alloys has been developed. The plating bath electrolyte is a modified Wood nickel solution. The addition of a biological detergent to the electrolyte yields a non-porous plating layer. The application of a low plating current along with moderately intense agitation of the electrolyte results in a strong interfacial bond between the irradiated foil and the plated nickel. The strength of this interfacial bond determines the quality of the electron-transparent thin area that is obtainable. Successful plating has been achieved with ion-irradiated pure Fe-Ni-Cr ternary, nickel, Ni-Cu binaries, US Prime Candidate Alloy (PCA), and Soviet EP-838 stainless steel. An unirradiated low-activation ferritic steel has also been successfully plated. An electron-transparent thin area is achieved by two-step twin-jet electropolishing, supplemented by ion sputtering. Micrographs of several irradiated alloys displayed in cross-section using this technique are presented.