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 Ni 9 Nb 2 P and Ni 2 NbP is proposed: L + Ni 9 Nb 2 P → Ni 2 NbP, The slopes of liquidus surface boundaries between Ni solid solution (Ni ss ), Ni 3 P, Ni 9 Nb 2 P and Ni 2 NbP along with two invariant reactions are proposed: L + Ni ss → Ni 3 P + Ni 9 Nb 2 P and L → Ni 3 P + Ni 9 Nb 2 P + Ni 2 NbP. A ternary amorphous alloy with a large undercooled region before crystallization (ΔT x = 15°C) is developed demonstrating the importance of phase equilibria in designing the alloy with high glass forming ability.