  Flash sintering phenomena are predominantly associated with ceramics due to
thermal runaway of their electric conductivity noticeably represented in
materials such as zirconia or silicon carbide. Because of their high electric
conductivity, flash sintering of metals is nearly inexistent. In this work, an
original metal powder flash sintering method based on a microwave approach is
presented. Within the developed approach, an unusually fast (60 s) thermal and
sintering runaway of Ti-6Al-4V powder is experimentally revealed under
microwave illumination. This phenomenon is simulated based on an
electromagnetic-thermal-mechanical (EMTM) model. The developed multiphysics
model reveals that the metal powder specimen's runaway does not result from its
intrinsic material properties, but results from the resonance phenomenon
thermally activated by the surrounding tooling material. The EMTM simulation
predicts with a very good accuracy the microwave repartition and the resulting
densification and powder specimen's shape distortions observed experimentally.
The comparison of the microwave and conventional sintering kinetics indicates
an important acceleration of the sintering behavior under microwave heating.
The developed sintering approach has a potential of the implementation for
time-effective mass production of small metal parts.
