A rapid preparation method for in situ nanomechanical TEM tensile specimens

Specimen preparation is a critical aspect in electron microscopy and is particularly challenging for in situ investigations that require specimens to fit onto specific testing devices. We report a modification of a substrate lift-off technique for thin films that enables users to produce specimens for in situ nanomechanical tensile testing. By depositing an electron transparent film, removing it from its substrate, and mounting it to a Cu grid (which serves for preparatory staging), rectangular specimens are focus ion beam (FIB) milled and mounted to push-to-pull or similar MEMS-like devices for nanomechanical testing. Using the FIB, the gauge length is milled into a reduced cross-section yielding the ‘dog-bone’ geometry. This use of this Cu grid-staging significantly reduces mounting and thinning steps for the direct film-to-device preparation as well as allows the testing device to be used multiple times for new specimens. Finally, we reveal ion-induced grain growth with improper milling and solute induced grain boundary embrittlement in the nanocrystalline alloy studied.