Abstract
The interfacial characterisation of aluminium alloy 6061 reinforced with Al2O3 particles was carried out using scanning and transmission electron microscopy on interfacial sections and by X-ray diffraction on the reaction products extracted by electrochemical dissolution. The value of these combined techniques in elucidating the interfacial reaction mechanisms was demonstrated. Single crystals of MgAl2O4, of octahedral shape, were observed at the (Al2O3)p/Al interfaces together with surface erosions of (Al2O3)p which formed around the MgAl204 crystals. In the heat treated composite a reduction in precipitate density in the alloy matrix was observed in the vicinity of the (Al2O3)p. Based on the experimental observations and thermodynamic considerations, the MgAl2O4 crystals which formed at the surface of the (Al2O3)p are believed to grow by consuming A12O3.
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