Distribution of transition metal elements in an Al-Si-Cu-based alloy

An Al-Si-Cu-based cast alloy was modified with transition metal elements Zr, V and Ti to achieve enhanced mechanical performance at elevated temperatures. Multiple microstructural characterization techniques were used to investigate the solidification segregation behavior of these transition metal elements and their partitioning to the primary intermetallic phases and secondary precipitates. Three transition metal elements were shown to segregate into the dendrite center to varying degrees. Two primary intermetallic phases enriched with different amounts of transition metal elements were identified as D022 and D023 phases. Zr was observed to concentrate much more than V and Ti in the nano-size secondary L12 precipitates, which formed in the matrix during post-solidification heat treatment.