TEM and XRD characterisation of commercially pure alpha-Ti made by powder metallurgy and casting

The hcp-structured alpha-Ti is one of the two basic phases (alpha-Ti and beta-Ti) materials. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the alpha-Ti phase in both as-sintered and as-cast alpha-Ti materials. The structure factor of the (0001) plane of the alpha-Ti phase is 0. No diffraction should thus occur from the (0001) plane of the alpha-Ti phase when characterised by either x-ray diffraction or electron diffraction. However, electron diffraction of the as-sintered alpha-Ti materials recorded unambiguous diffraction from the (0001) plane as well as (000 1) where l =2n +1 (n is integer). A detailed analysis has clarified that this is a result of double diffraction arising from the two strong neighbouring (10 (1) over bar0) and ((1) over bar 011) diffraction planes. The same phenomenon also occurred to the characterisation of as-cast alpha-Ti materials