Imaging ultrafine grains in machined tantalum subsurface using a focused ion beam

In this study we have identified ultrafine grains in the subsurface of a machined tantalum surface. It has been shown that precision sectioning using focused ion beam milling and imaging using ion-induced secondary electrons are capable of resolving ultrafine grains of the order of 150–200 nm. A good correlation has been found between X-ray full-width-at-half-maximum data and the microstructural variation as a function of depth.