Failure Analysis of Local Electrodes

A failure analysis of local electrodes has been performed with the use of a dual beam ion miller/scanning electron microscope. Each aperture was examined before and after use in the local electrode atom probe. In addition, many atom probe specimens were characterized after the experiment to correlate the condition of the specimen with that of the aperture. The predominant failure mode of specimens was found to be melting even for high melting point materials such as tungsten and superalloys. A much less frequent mode of failure was specimen rupture which generally occurred with very brittle materials. The lifetime of the aperture in the local electrode atom probe was found to be dependent on the shape and position of the debris from the failure rather than the number of ions collected or the number of specimens characterized