|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Material Design Approaches and Experiences IV
||Alloying Effects on Oxidation Mechanisms in Polycrystalline Co-Ni-Al-W-Ta Base Superalloys
||Farah Ismail, Barbara A Shollock, Trevor C Lindley, David Dye, Mark C Hardy
|On-Site Speaker (Planned)
Oxidation mechanisms in alloys with different Co-Ni ratios and Cr, Al contents were investigated using isotopic tracing combined with focused ion-beam secondary ion mass spectrometry (FIB-SIMS). Two distinct oxide morphologies were observed on the surface: a facetted Al-Co-Ni oxide, and a nodular Al-Cr-Co-Ni oxide, suspected to be spinels. Al-addition leads to the formation of continuous alumina-rich layer in the subsurface region. Cr-additions indirectly improved the oxidation resistance of these alloys, promoting the development of a protective alumina layer adjacent to the metal. Reducing the proportion of Ni resulted in thicker surface oxide scale with a non-continuous subsurface alumina-rich layer. The outer scale comprised oxides less than 1 μm thick when 10 at.% of Al and 15 at.% of Cr were added to the alloy. This study demonstrates that protective oxide scales can be formed in Co-Ni-Al-W-Ta alloys.
||Planned: TMS Journal: JOM