Preparation of Stainless Steel Surfaces for Scanning Probe Microscopy

The properties of metals and alloys depend on their microstructure, including grain size, number of phases, amounts of phases, and phase distributions within the sample at the micrometer scale. Microstructure is elucidated through metallographic examination. Typical preparation steps for specimens of this type include mounting in a thermosetting resin, polishing to a mirror-like finish, and in some cases etching with a weak acid (chosen to selectively dissolve grain boundaries or specific phases). Conventional techniques used for subsequent examination include light optical microscopy (LOM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The latest developments in metallographic analysis are focused at the nanometer scale and require precise sample preparation. Scanning probe microscopy (SPM) techniques such as atomic force microscopy (AFM) are well-suited for the analysis of metallographic features at sub-micrometer length scales including the following: precise determination of carbide morphology, topographic analysis of creep cavities and corrosion, and determination of phase distributions using stiffness or magnetic data [1]. The suite of SPM techniques are non-destructive, allowing the same area of interest to be examined later by other techniques. This saves considerable time compared with destructive metallographic techniques and enables direct comparisons of the resulting data.