A rotating disk electropolishing technique for TEM sample preparation

A new electropolishing technique is presented for the preparation of thin metallic foils for transmission electron microscopy (TEM). The technique employs rotating disk electrodes, well known in electrochemistry, both for the determination of appropriate electropolishing conditions and for the application of those conditions to the preparation of thin foils themselves. By providing more accurate control over the critical polishing parameters of applied voltage and electrolyte flow, the new method can improve reliability and reproducibility in the production of TEM foils. To demonstrate the approach, a specially adapted rotating disk assembly designed for this study is compared to the standard twin-jet polishing technique for the preparation of a nickel base superalloy containing cubic shaped precipitates of the γ′-phase separated by the γ-solution matrix that can be difficult to prepare due to the preferential dissolution of one of the phases.