Jet-Polishing Iridium for TEM

Abstract

Iridium is an extremely dense and chemically resistant element. These properties make it one of the most difficult metals to examine by TEM. Various electrochemical techniques for preparing Ir TEM samples which use the "window" method have been reported. Iridium has also been thinned by ion milling. However, the "window" method requires relatively large foil samples and the technique is likely to introduce dislocations into the microstructure. We also verified that techniques using KCN resulted in severe grain boundary attack. Ion milling is very slow and creates "black spot" ion damage which can mask small microstructural features such as precipitates or small dislocation loops. A relatively rapid jet-polishing technique which alleviates these problems is described below.