In situ lift-out dedicated techniques using FIB–SEM system for TEM specimen preparation

Abstract

The recent emergence of the focused ion-beam (FIB) microscope as a dedicated specimen preparation tool for transmission electron microscopy (TEM) has extended the reach of TEM to a wider variety of problems in materials science. This paper highlights three examples of using FIB–SEM lift-out techniques for preparing site-specific and crystallographic orientation-specific thin-foil specimens. An in situ lift-out technique used to extract thin foils from across a local grain boundary in bulk Al alloy and from individual fine Al atomised powder particles (down to 20μm in diameter) was performed with real-time secondary electron imaging within the chamber of a FIB–SEM system. In conjunction with electron backscatter diffraction (EBSD), the FIB is used for extracting TEM foil with a specific crystallographic orientation aligned normal to the broad plane of the foil. The above technique has been demonstrated using a dual-phase Ti–Si alloy for the exploration of orientation relationship between constituent phases. Furthermore, it is suggested that FIB is more applicable for preparing thin foils from hydrogen-sensitive metals (such as titanium alloys) than conventional thinning techniques, which tend to induce ambiguous artifacts in these foils.