Abstract
The heavily faulted M2B-type borides precipitated in the long-term aging Ni-based superalloys with B addition are comprehensively studied at an atomic scale. By means of high angle annular dark field (HAADF) imaging technique in the aberration corrected scanning transmission electron microscope (STEM), atomic configurations of various kinds of structural intergrowth in the profoundly faulted M2B phase are directly imaged. The polytypic M2B phase is mainly composed of C16, Cb and Ca structural variants, in which planar defects and the resultant long period stacking order (LPSO) structure are identified. In combination of the advanced spectrometry imaging technique with density functional theory (DFT) calculations, it is proposed that the polytypic feature is attributed to the conservation of the basic polyhedron of anti-square prisms.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 64-72 |
| Number of pages | 9 |
| Journal | Acta Materialia |
| Volume | 100 |
| DOIs | |
| State | Published - Nov 1 2015 |
Funding
This work is supported by the National Natural Foundation of China (No. 11327901 ) and Ministry of Science & Technology of China ( 2010CB631206 and 2009CB623705 ). We are grateful to Mr. J. Wang for bulk sample preparation, to Mr. B. Wu and Mr. L.X. Yang for technical support at Titan platform, and to Dr. Y.L. Tang and Dr. Z.B. Yu for useful discussions.
Keywords
- Aberration corrected transmission electron microscope
- Atomic configurations
- Ni-based superalloy
- Polytypic MB-type boride
- Structural intergrowth
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys