High Resolution TEM Investigation of Ultra High Temperature Materials

The characterization of ceramics at nanoscale level is of fundamental importance, especially when the interfaces between two different phases play the major role in determining the efficacy of toughening mechanisms. In this framework lies the activity of microstructural characterization by transmission electron microscopy (TEM) combined with other analytical techniques, such as electron diffraction, energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). The main purpose is a thorough study of the distribution, chemistry and crystallinity of secondary phases and of the triple point junctions, as well as the presence of intergranular films. ISTEC personnel is mainly focused on the investigation of UHTC reinforced with different kinds of fibers, as foreseen by a renewed contract with the European Office of Aerospace Research and Development (EOARD) - Air Force Office of Scientific Research (AFOSR). TEM analyses performed so far revelaed the transformation mechanisms of the fibers during the sintering stage and enabled to better understand the complex relationship between processing, microstructure and mechanical properties of UHTCs.