Analysis of Facets and Other Surfaces Using Electron Backscatter Diffraction

Abstract

A facet is defined as ‘one side of a many-sided body.’ With regard to grains in a polycrystal, a facet can be an intergranular or transgranular fracture surface (Field 1997; Randle and Hoile, 1998; Randle, 1999), or the surface of a grain or phase boundary (Randle, 1997). Figure 23.1 shows the appearance of intergranular fracture surfaces in an aluminium alloy revealed as a result of liquid metal embrittlement by gallium. This is, of course, an unusual view of grain boundaries; usually they are revealed by etching a polished surface to show the trace of the grain boundary network. Frequently, fracture surfaces and grain boundaries have very specific crystallographic identities. This is also true of other planar features in materials, such as intergranular or transgranular microcracks, (Liu et al., 1992) or slip traces (Blochwitz et al., 1996; Lin and Pope, 1996; Raabe et al., 1997). It is possible to extend the capabilities of EBSD to obtain the crystallographic indices of these flat surfaces (i.e., planes). Such a strategy is a precursor to a three-dimensional view of microtexture. This chapter gives an overview of the state-of-the-art of EBSD analysis of facets and surfaces.