Precipitation of partially coherent α-Al(Mn,Fe)Si dispersoids and their strengthening effect in AA 3003 alloy

The orientation relationship (OR) between alpha-Al(Mn,Fe)Si dispersoids and the Al matrix in AA 3003 alloy has been systematically studied by selected area electron diffraction patterns. New types of ORs between the cubic dispersoids and the cubic matrix phase have been found as < 1 -1 1 >(p)//< 1 -1 1 >(m) and {5 -2 -7}(p)//{0 1 1}(m). High-resolution transmission electron microscopy and crystal structure simulation studies on the habit planes of dispersoids show that alpha-Al(Mn,Fe)Si dispersoids are partially coherent with the Al matrix. Precipitation of alpha-Al(Mn,Fe)Si dispersoids in the alloy has been found to have a strong influence on enhancing both the yield strength and tensile strength of the alloy. The dispersion-hardening effect of the dispersoids has been explained by the Orowan mechanism. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.