Microstructures and Mechanical Properties of A356 Aluminum Alloys after Modificated by Adding Amorphous Alloy

A356 aluminum alloy with Al-5Ti-1B pre-refine treatment was modified by adding various amounts of Zr₅₆Co₂₂Al₁₆Ag₆ amorphous alloy ribbons, and then solid solution and aging heat treatment was executed on the aluminum alloy. The microstructure and mechanical properties of the aluminum alloy were studied, and the amorphous ribbon's refine mechanism was also discussed. The results show that with the increase of amorphous alloy ribbon's adding amounts, grain size and the secondary dendrite spacing of the aluminum alloy all decrease, and the mechanical properties of the aluminum alloy are improved. Dispersed granular Al₃Zr phase is found in eutectic structure, the phase increases the number of nucleus, hence refines the grains. Adding 0.4wt% Zr₅₆Co₂₂Al₁₆Ag₆ amorphous alloy ribbons and setting incubation period of 10 min could make the aluminum alloy obtain the best refining effect, and after solid solution and aging treatment, tensile strength and elongation of the aluminum alloy owned the higher mechanical properties, compared with the aluminum alloy without adding amorphous ribbons, its tensile strength and elongation increased by 7%and 64.4%, respectively.