The crystallization process of amorphous alloy Al 90RE 5Ni 5 can be written as: Am Al 90RE 5Ni 5 — nano α-Al + Am AlRENi — α-Al + Al 3Ni + Al 11RE 3. The structure of the Al-based amorphous alloy was explained by an atomic cluster model. The growth of nanoscale α-Al in an amorphous matrix was reported. The hardening process can undergo two stages. One is controlled by a shear deformation mechanism of the amorphous matrix. Another is decided by the dislocations in the nanoscale α-Al grain. The microhardness of the amorphous alloy dispersion by nanoscale α-Al depends strongly on the average grain sizes D and the spacing δ between the grains in an amorphous matrix.