Nanocrystalline composites of aluminium 6061 alloy matrix with additions of ceramic phase alpha-Al2O3
Jan Dutkiewicz, Wojciech Maziarz, Lidia Lityńska-Dobrzyńska, Anna Góral, Agata Kukuła, Adam Kanciruk
Quarterly No. 1, 2010 pages 76-80
DOI:
keywords: aluminium matrix nanocrystalline composites, vacuum hot pressing, mechanical alloying, TEM
abstract Mechanical alloying of 6061 aluminium alloy powder mixed with 2% of Zr and 10 or 20% of nano powder alpha-Al2O3 was applied in a high energy ball mill in order to refine the grain size and to mix exactly the components. A final grain size of milled powder was estimated to be below 50 nm with a uniform distribution of Al2O3 powder particles. No agglomeration of Al2O3 powder particles was observed. Hot pressing at 380oC of milled powders do not causes significant grain growth and the average size of alpha-Al solid solution was estimated at 100 nm; only a few grains approaching 200 nm were observed. The grain growth was limited due to the addition of 2% of Zr forming Zr2Al phase and dissolving in al solid solution. Obtained composites have shown a low porosity of less than 1%. The nanocomposites containing 20% of Al2O3 have shown a high hardness of 310 HV and a high compression strength near 770 MPa. The tests proved a good plasticity of samples attaining 15% of plastic compression. Compression curves have shown jumps of stress in the plastic deformation range due to Portevin-Le Chatelier effect.