High resolution energy dispersive spectroscopy mapping of planar defects in L12-containing Co-base superalloys
| Autor: | Michael S. Titus, G. Babu Viswanathan, Tresa M. Pollock, Alessandro Mottura, Michael J. Mills, Akane Suzuki |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Shearing (physics)
Materials science Polymers and Plastics Superlattice Metals and Alloys Energy-dispersive X-ray spectroscopy Analytical chemistry Electronic Optical and Magnetic Materials Superalloy Creep Scanning transmission electron microscopy Ceramics and Composites Spectroscopy Single crystal |
| Zdroj: | Acta Materialia. 89:423-437 |
| ISSN: | 1359-6454 |
| DOI: | 10.1016/j.actamat.2015.01.050 |
| Popis: | Local chemical fluctuations in the vicinity of superlattice intrinsic stacking faults (SISFs) have been observed via high resolution energy dispersive X-ray spectroscopy (EDS) mapping in new single crystal Co- and CoNi-base superalloys containing γ ′ -(L1 2 ) precipitates. The SISFs were formed during high temperature tensile creep at 900 °C. Chemical fluctuations were found to greatly influence the SISF energy, which was calculated from density functional theory in Co 3 (Al, Ta, W) compounds at 0 K. The local SISF structure was found to be comprised of four D0 19 (0001) planes that were enriched in W and Ta, as revealed by high resolution scanning transmission electron microscopy (HRSTEM) imaging and EDS mapping. The precipitates were determined to accommodate up to 22% of the plastic deformation accrued during an interrupted creep test to 0.6% creep strain. The driving forces for segregation are discussed, and new models for shearing of the ordered precipitates are proposed. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect