CRYSTALLIZATION AND HIGH MECHANICAL STRENGTH OF AL-BASED AMORPHOUS-ALLOYS

Crystallization behavior upon aging and its influence on mechanical properties were examined for Al88Ni10Y2 and Al88Ni10Ce2 amorphous alloys. The crystallized structure of the amorphous alloys consists of coexistent amorphous and fcc-Al phase with a particle size of 5 to 12 nm. The thermal stability increases significantly with an increase of the precipitation amount (V(f)) of the nanoscale Al particles. The hardness (H(v)) and tensile fracture strength (sigma(f)) of these amorphous alloys containing the nanoscale Al particles are about 2.0 and 1.3 times higher than those for the amorphous single phase alloys with the same compositions, respectively. Then, the good bending ductility of these alloys remains unchanged. This increase in sigma(f) is considered because the defect-free nanoscale Al particles homogeneously dispersed in the amorphous matrix act as an effective resistance to suppress shear sliding of the amorphous matrix. The highest sigma(f) is much higher for Al88Ni10Ce2 alloy than for the Al88Ni10Y2 alloy. The difference presumably comes from stronger bonding force between Al and Ce atoms compared with that between Al and Y.