Phase equilibria and amorphous phase formation in the Ni-Nb-P ternary alloy system

Abstract

Liquidus projections in the Ni-rich comer of the Ni-Nb-P ternary system have been studied through the analysis of as-cast microstructures. A peritectic reaction involving Ni9Nb2P and Ni2NbP is proposed: L+Ni9Nb2P→Ni2NbP. The slopes of liquidus surface boundaries between Ni solid solution (Niss), Ni3P, Ni9Nb2P and Ni2NbP along with two invariant reactions are proposed: L+Niss→Ni3P+Ni9Nb2P and L→Ni3P+Ni9Nb2P+Ni2NbP. A ternary amorphous alloy with a large undercooled region before crystallization (ΔTx = 15 °C) is developed demonstrating the importance of phase equilibria in designing the alloy with high glass forming ability.