XRD and TEM study of the quasicrystalline phase in pellets consolidated using spark plasma sintering

Abstract number
397
Event
European Microscopy Congress 2020
DOI
10.22443/rms.emc2020.397
Corresponding Email
[email protected]
Session
PSA.2 - Metals & Alloys
Authors
Professor Ruitao Li (2), Professor Khiam Aik Khor (3), Dr Zaoli Zhang (1), Dr Chris B Boothroyd (2), Associate Professor ZhiLi Dong (2)
Affiliations
1. Erich Schmid Institute of Materials Science Austrian Academy of Sciences
2. School of Materials Science and Engineering, Nanyang Technological University
3. School of Mechanical and Aerospace Engineering, Nanyang Technological University
Keywords

Quasicrystal, Spark Plasma Sintering, Composite

Abstract text

The production of quasicrystal powders by gas atomization has been commercialized. Among various quasicrystals synthesized, Al-Cr-Fe and Al-Cu-Cr-Fe quasicrystals are very promising materials for coatings and reinforcements in composites due to their high hardness, good wear and corrosion resistance and the relatively low cost of their constituent metals [1]. As these quasicrystals are metal based, the behavior of bonding between the quasicrystalline reinforcement phase and the metal matrix is superior to that for ceramic phase reinforced metal-matrix composites. However, long duration sintering can result in phase changes and decrease the beneficial properties of the quasicrystals in the composites.

In our study, we employed spark plasma sintering to shorten the heating duration for the Al-Cr-Fe and Al-Cu-Cr-Fe quasicrystal powders and thus minimize the chance of phase changes when fabricating quasicrystalline reinforced composites. The phases of the sintered compacts were analyzed using x-ray diffraction. The microstructure of the quasicrystalline phases was further studied using high resolution transmission electron microscopy.

Experimental results showed that even when the heating duration was as short as 30mins during spark plasma sintering at 650ºC, phase changes could still occur. X-ray diffraction patterns showed peaks from the decagonal Al-Cr-Fe phase while HRTEM images revealed that in decagonal Al-Cr-Fe quasiperiodic planes were periodically stacked along the 10-fold axis with a periodicity of about 1.2nm. Spark plasma sintering of icosahedral Al-Cu-Cr-Fe and pure Al blended powders was conducted at 450ºC for 10mins and no phase change was detected using X-ray diffraction or high resolution electron microscopy. This implies that spark plasma sintering is effective in fabricating quasicrystal reinforced Al-based composites.


References

[1] V Demange, J Anderegg, J Ghanbaja, F Machizaud, D Sordelet, M Besser, P Thiel and J Dubois, Applied Surface Science 173 (2001), p 327-338.