|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Deformation and Damage Mechanisms in High Temperature Ni, Co and Fe-based Superalloys
||L1<sub>2</sub> Phase Stability and Coarsening Behavior in Co-Al-W-base Superalloys
||Katelun Wertz, Donald Weaver, S. Lee Semiatin, Michael Mills, Stephen Niezgoda, Rajiv Shivpuri
|On-Site Speaker (Planned)
The high temperature mechanical performance of the Co-Al-W system is a result of ordered L1<sub>2</sub> precipitates that form within a disordered matrix, much like traditional nickel-based superalloys. However, unlike the nickel systems, the stability of the strengthening phase remains in question. Experimental observations indicate the phase is metastable as precipitates from most discreet ternary compositions dissolve after extended times near relevant application temperatures. Recent density-functional-theory calculations suggest phase stability in ternary alloys with specific Al:W ratios, but experimental confirmation has yet to be shown. To that end, a static long-term aging study was performed on as-cast and cast-and-hot-worked ternary Co-Al-W alloys of varying Al:W ratios, as well as quaternary and quinary compositions containing alloying additions of interest. The compositions were evaluated at processing and application temperatures for various aging times to 5000 hours. The effects of composition, aging time, and stored work on coarsening/dissolution behavior of the L1<sub>2</sub> phase were determined.
||Planned: Supplemental Proceedings volume