Precipitation of Si particles in a super-rapidly solidified Al-Si hypereutectic alloy

Fine silicon particles of approximately 20 nm in average diameter were dispersed in the Al matrix of a hypereutectic Al-Si alloy powder produced by the spinning water atomization process. This powder was sintered at a temperature between 623 and 773 K for a maximum period of time of 20.4 ks. The silicon particles grew during sintering but the size remained at a sub-micron level. The Vickers hardness varied from 150 and 180, depending on the sintering temperature. These values of the Vickers hardness were two to three times as high as those of conventionally cast bars of the same alloy. (C) 2003 Elsevier Science B.V. All rights reserved.