| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advancing Current and State-of-the-Art Application of Ni- and Co-based Superalloys
|
| Presentation Title |
Grain Boundary Chemistry and Mechanical Properties of a Multicomponent Co-based L12–ordered Intermetallic Alloy |
| Author(s) |
Francesca Long, Sung II Baik, Ding Wen Chung, Fei Xue, Eric A Lass, David N Seidman, David C Dunand |
| On-Site Speaker (Planned) |
Fei Xue |
| Abstract Scope |
The chemistry, thermodynamics and mechanical properties of the L12-ordered Co3(Al,W) γ′ phase are crucial to the understanding of γ(fcc)/γ′(L12) cobalt-base superalloys. A single-phase γ′ alloy with composition Co-30Ni-11Al-5.5W-4Ti-2.5Ta-0.10B (at.%) and γ′ solvus temperature of 1268°C was recently identified using a Calphad-methodology. Scanning and transmission electron microscopy reveal that the single-phase microstructure is stable at 900 and 1000°C for 1000 h and at 1100°C for 168 h without other phases observed, resulting in a similar level of microhardness within grain interiors. Atom probe tomography of a grain boundary reveals depletion of Co, Ni, W and Ta and enrichment of Al and B. A marked yield stress anomaly is observed with yield strength increasing from ~300 to ~700 MPa as temperature increases from 20 to 800°C, stronger than L12-Co3(Al,W) and Ni3Al. The creep tests at 850°C show a power-law behavior with a stress exponent and an activation energy similar to single-phase L12-Ni3Al. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |