High Strain Rate Superplastic Deformation in 6061 Alloy with 1% SiO₂ Nano-Particles

Four 6061 aluminum systems were prepared, including the cast 6061 alloy processed by TMT or ECAP, the PM 6061 alloy, and the modified PM 6061 alloy added with 1 vol% nano-SiO₂. The modified 6061/l%nano-SiO₂ alloy possessed a grain size ∼0.5 μm and maintained fine grain size upon loading at high temperatures, resulting in HSRS over 300% at 550-590 °C and 1-5×10^-1 s^-1. The grain boundary misorientation distribution in the modified 6061/1%nano-SiO₂ alloy was also most random compared with other three unmodified 6061 alloys. The current results suggest that the addition of a small amount (1 vol%) of cheaper SiO₂ or Al₂O₃ nano-particles into commercial Al alloys can effectively suppress grain growth at high temperatures and enhance HSRS, similar to the effects by adding 15-25 vol% micro-sized SiC or Si₃N₄ reinforcing particulates or whiskers.