|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials for High Temperature Applications: Next Generation Superalloys and Beyond
||Effect of Trace Levels of Si on Grain Boundary Segregation in an Ir Alloy
||Dean Pierce, Govindarajan Muralidharan, Lee Heatherly, Cecil Carmichael, George Ulrich
|On-Site Speaker (Planned)
Iridium (Ir) alloy DOP-26 (Ir-0.3W-0.006Th-0.005Al wt.%) is used as a fuel cladding material in radioisotope thermoelectric generators for space applications owing in part to its excellent high temperature impact ductility. Previous work has shown that additions of 50 to 1500 wppm of silicon (Si) to DOP-26 resulted in grain boundary Si concentrations of up to ~60 times bulk levels, contributing to loss of impact ductility. The focus of the present work was to understand the effect of high temperature annealing treatments on Si segregation to grain boundaries in Ir-alloys with lower levels of Si (less than 50 wppm). Auger Electron Spectroscopy on in-situ fractured specimens was used to characterize grain boundary segregation. Effects of bulk Si levels and annealing temperatures on the observed Si segregation to grain boundaries will be discussed.