International journal of materials research vol:99 issue:11 pages:1222-1228
This study focuses on the microstructure formation in two Al-Cu-Ag alloys with near-eutectic composition on either side of the alpha(Al)/theta-Al2Cu groove. The alloys solidified equiaxially with two different cooling rates for each composition of alloy. The primary phases formed are alpha(Al) or theta-Al2Cu, but univariant and invariant eutectic reactions are common. In hypoeutectic samples macrosegregation of the alpha(Al) phase occurred. The univariant alpha(Al)/theta-Al2Cu eutectic in these samples is formed by coupled two-phase structures. The univariant eutectic in the samples, which exhibit primary theta-Al2Cu, grew partially competitively due to the alpha(Al) single phase instability.