The constituent of precipitations phases of aged melt-spun AlMgCu ribbons was characterized by high-resolution transmission electron microscopy and microhardness test. The cooling rate of as melt-spun ribbon was estimated to be 1.60×105 K/s from the empirical relation. The samples were aged at 200 ＆#176;C for 16 h after solution treatment. Two precipitation phases, i.e. Al2CuMg and abnormal amorphous SiO2 were identified in the T6 melt-spun AlMgCu ribbon. The crystal structure and stoichiometric composition of Al2CuMg phase are in good agreement with the reference results [WANG et al （2007; 2005）]. The combined experiments show that the formation of abnormal amorphous SiO2 appears to be associated with the higher cooling rate in melt-spinning process and has no significant effect on the peak hardness.
