| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
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| Symposium
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Microstructural Template Consisting of a Face-Centered Cubic Matrix with Ordered Precipitates: Microstructural Evolution and Properties
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| Presentation Title |
D022 + D022’ Dual-phase Microstructure in As-cast Al-Mo-Ti Alloys |
| Author(s) |
Andreas Leineweber, Mario J. Kriegel, Stefan Martin, ShunLi Shang, Zi-Kui Liu |
| On-Site Speaker (Planned) |
Andreas Leineweber |
| Abstract Scope |
Certain Al-rich Al-Mo-Ti alloys (e.g. Al73Mo22Ti5) obtained in the as-cast state contain a peculiar microstructure, which consists, according to powder X-ray diffraction analysis of tetragonal D022-Al3(Mo,Ti) as well as of an unprecedented orthorhombic variant thereof, called D022'-Al3(Mo,Ti). Microstructure analysis reveals intergrowth of both phases in a checkerboard microstructure with parallel c-axes and alternate orientations of D022'. Energy dispersive X-ray analysis demonstrates a higher Mo content in D022'-Al3(Mo,Ti) than in D022-Al3(Mo,Ti). The crystal structure of D022'-Al3(Mo,Ti) can be related to shear instability of hypothetical tetragonal D022-Al3Mo revealed by first-principles calculations. Analysis of the lattice metrics of D022' using so-called Aizu strain tensors, commonly used to assess spontaneous strain in ferroelastics, reveals that the strain of D022'-Al3(Mo,Ti) resembles that of the stable monoclinic fcc-based superstructures of binary Al3Mo and Al8Mo3. The checkerboard microstructure minimizes strain energy of the microstructure, which likely has formed by unmixing during or after solidification. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |