In situ TiB2 particulate reinforced near eutectic Al-Si alloy composites

In situ TiB2 particulate reinforced near eutectic Al-Si alloy composites fabricated by the melt reaction composing (MRC) methods have been investigated. It has been shown that minute TiB2 particles (less than 1 mum) uniformly distribute in the eutectic structure and they are interlaced with the coralline-like eutectic Si, while there are very few TiB2 particles in alpha-Al. It has been also shown that in situ TiB2 particles can enhance the tensile strength of the Al-Si alloy matrix. The strengthening effect increases with increasing TiB2 content. The ultimate tensile strength (UTS) at room temperature of as-cast 6%TiB2/Al-Si-Mg composite is 296 MPa, that is a 14.7% increase over the matrix, and its elongation at fracture is 5.5%. After heat-treatment (T6), the UTS of the composites reaches 384 MPa. The strengthening mechanism has been discussed. (C) 2002 Published by Elsevier Science Ltd.