TEM Investigation of Metal/Ceramic Interfaces in AA7475/AlN or Al₂O₃ Nano-Composites

Abstract:

Microstructure of two types of 7475 aluminum alloy matrix composites with additions of 10 wt.% and 20 wt.% of Al₂O₃ or AlN were investigated. Pre-alloyed 7475 aluminum powders were mixed with ceramic particles and milled in a high energy planetary Fritsch ball mill for up to 40h. Subsequently, it was compacted at 380°C/600 MPa. The microstructure of the obtained composites was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The performed investigations proved that both types of composites show a good dispersion of ceramic phases. The composite matrix was characterized by fine grain size, i.e. less than 100 nm and contained a high density of even smaller, Zn, Cu or Fe rich precipitates. The EDS chemical analysis indicated local presence of MgO at the metal/ceramic interfaces in both types of composites. The presented approach allowed to produce a composite with AlN or Al₂O₃ particles in nano-crystalline aluminium alloy matrix.

References

[1] K.H. Min, B.-H. Lee, S.-Y. Chang, Y. D. Kim: Mater. Lett. Vol. 61 (2007), p.2544.

[2] R.N. Rao, S. Das: Mater. Design Vol. 31 (2010), p.1200.

[3] A. Kalkanlı, S. Sencer Yılmaz, Mater Design Vol. 29 (2008), p.775–780.

[4] B. Xiong, Z. Xu, Q. Yan, B. Lu, C. Cai: J. Alloy. Compd. Vol. 509 (2011), p.1187.

[5] M. Chedru, J.L. Chermant, J. Vicens: J. Mater. Sci. Lett. Vol. 20 (2001), p.1577.