Microscopic mechanisms of spark plasma sintering in a TiAl alloy
Résumé
A method to observe the mechanisms occurring at the neck between TiAl powder particles during interrupted spark plasma sintering (SPS) cycles has been developed. It is based on co- sintering of a mixture of equilibrated TiAl prealloyed powder with a small amount of Ti powder, the latter taking the place of the pores. Dense samples were obtained, which could be prepared for scanning and transmission electron microscopies (SEM, TEM) by standard procedures. TiAl- Ti reaction proved to be sufficiently limited to allow observations of necks between TiAl particles. Though the neck regions exhibit large deformations, clean and dislocation-free grains are observed by TEM in these regions. This is interpreted in terms of classical high temperature mechanisms: dislocation activity followed by dynamic recrystallization. No mechanisms specific to the SPS have been observed. Copyright © 2014 by The Minerals, Metals & Materials Society.
Mots clés
Dynamic recrystallization
Exhibitions
Mechanisms
Metallurgy
Spark plasma sintering
Titanium compounds
Transmission electron microscopy
Dislocation activity
Dislocation-free
High temperature
Microscopic mechanisms
Pre-alloyed powder
Scanning and transmission electron microscopy
Standard procedures
TiAl
Titanium alloys