2001 Volume 42 Issue 8 Pages 1781-1789
Four 6061 aluminum systems were prepared in this study, including the DC cast 6061 alloy processed by TMT and ECAP, the PM modified 6061 alloy added with 1 vol% nano-SiO2, and the commercial 6061/20%SiCw composite. All materials possessed fine grain sizes ∼ 0.3–1 \\micron after processing, but only the latter two could maintain fine grain size upon loading at high temperatures and achieved HSRS over 300% at 570–590°C and 1–5×10−1 s−1. The texture was weaker and the grain boundary misorientation distribution was more random in the 6061/1%nano-SiO2 alloy as compared with the unmodified 6061 alloys. The 1%nanoSiO2 modified alloy exhibited low stresses ∼ 4 MPa, true strain rate sensitivity ∼ 0.5, smooth GBS and a limited amount of liquid phase at high temperatures and strain rates, similar to those observed in HSRS composites. The current results suggest that the addition of a small amount (1 vol%) of SiO2 or Al2O3 nano-particles into commercial Al alloys can effectively suppress grain growth at high temperatures and enhance HSRS.