Phase transformations under thermal treatment in Al-12%Si-Zr system with metastable structure synthesized by compression plasma flows impact

Phase transformations in Al-12%Si surface layer after alloying with Zr atoms by plasma impact and following thermal treatment at 450–550°C were studied in this work. Plasma impact resulted in formation of a metastable τ 1 phase with tetragonal structure D0 22 in the alloyed layer. The volume fraction of τ 1 diminished with growth of energy density absorbed by the surface layer and increase of temperature during annealing. The decomposition of the τ 1 phase and the formation of ZrSi 2 upon annealing for 30 min was observed at a temperature of 550°C.