Spark plasma sintering mechanisms at the necks between TiAl powder particles

In order to precise the role of the electric current involved in the spark plasma sintering (SPS) technique on the microscopic mechanisms occurring at the necks between TiAl powder particles during densification, transmission electron microscopy thin foils have been extracted at the necks on interrupted states, for the first time, by focused ion beam. Microscopic plasticity mechanisms and recovery-recrystallization phenomena have been identified. The densification rate, which has been shown in this study to occur by deformation of the powder particles at a deformation rate of 10(-3) s(-1), can be accounted for by these phenomena. In particular, no specific effect, as signs of electric arcs, plasma or local overheating for example, induced by the SPS current, have been detected. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.