Abstract
Co-Al based superalloys have been considered as the promising alternatives to Ni-Al based superalloys. Appropriate alloy design can stabilize a dual phase structure of face-centered cubic (FCC) Co matrix and L12 Co3(Al, X) intermetallics and avoid precipitation of B2 CoAl intermetallics for Co-Al based superalloys. It has been shown that stable Co3Al single phase compound does not exist. Instead, at such a chemistry, Co-Al binary phase diagram predicts the coexistence of hexagonal close-packed (HCP) Co and B2 CoAl at room temperature. Here we report the synthesis of stoichiometric Co3Al via magnetron sputtering. Transmission electron microscopy investigations identified metastable phases of Co3Al, dominated by HCP supersaturation with minor L12 intermetallics. Furthermore, the phase transformation from HCP-to-FCC Co3Al induced by stacking faults in Co/Co3Al multilayers is also discussed. This investigation provides new insights on the crystal structures of stoichiometric Co3Al and the design of novel Co-Al based alloy systems.
| Original language | English |
|---|---|
| Article number | 116184 |
| Journal | Scripta Materialia |
| Volume | 250 |
| DOIs | |
| State | Published - Sep 1 2024 |
Funding
The authors acknowledge financial supports from NSF-DMR-2210152. XS is supported by DOE-BES under grant No. DE-SC0016337. H.W. acknowledges the support from the U.S. Office of Naval Research (N00014-22-1-2160). We are also thankful to discussions with Dr. Yashashree Kulkarni and Anand Mathew from Department of Mechanical Engineering, University of Houston. The authors acknowledge financial supports from NSF-DMR-2210152. XS is supported by DOE-BES under grant No. DE-SC0016337 . We are also thankful to discussions with Dr. Yashashree Kulkarni and Anand Mathew from Department of Mechanical Engineering, University of Houston.
Keywords
- Lattice parameters
- Metastable phases
- Stacking faults
- Stoichiometric CoAl
- Transmission electron microscopy