Reverse ulta-microtomy: a new method of TEM sample preparation

Abstract

Two variations of a new method of TEM metal sample preparation are proposed, hereby labeled RUM1 and RUM2, for “reverse ultra-microtomy” 1 and 2, respectively. With these techniques, the TEM samples are formed from bulk specimens by successively slicing off layers, with an ultra-microtome, until the remnant is partially thinned to electron transparency. This requires the sample to be embedded with excellent adhesion in a mounting material whose mechanical properties resemble that of the sample. While these methods are by far slower than ordinary microtomy wherein the individual slices are used as samples, preparation times are comparable to those for creating TEM samples by standard techniques. Furthermore, the methods (i) can be used where electropolishing fails, (ii) can be favorably applied to finely layered materials and composites, (iii) permit studies of near-surface structure gradients, and (iv) permit the simultaneous observation of an original surface and the underlying material. The methods have been successfully demonstrated through comparisons between samples created through RUM1 and 2 and standard TEM samples. Artifacts caused by the new method of reverse microtoming are shown to be very much reduced compared to direct microtoming.

Keywords:

• Composites
• Metal composites
• Microtomy
• Sample preparation
• TEM samples
• Ultra-microtomy