Zr–Al–Ni Amorphous Alloys with High Glass Transition Temperature and Significant Supercooled Liquid Region

Abstract

Amorphous Zr–Al–Ni alloys exhibiting a wide temperature region of supercooled liquid state and a high reduced glass transition temperature (Tg⁄Tm) were formed over a composition range from 0 to 37 at% Al and 3 to 67%Ni by melt spinning. The temperature span ΔTx(=Tx−Tg) between Tg and crystallization temperature (Tx) reaches as large as 77 K for Zr60Al15Ni25. The Tg⁄Tm is also as high as 0.64 in the vicinity of Zr60Al20Ni20 and their Zr–Al–Ni alloys are concluded to have a large glass-forming capacity. The Tx and hardness (Hv) increase with increasing Al and Ni contents in the range from 660 to 860 K and 400 to 720, respectively, and the tensile strength also has a similar compositional dependence in the range of 1335 to 1720 MPa. The compositional effect on Tx and Hv was presumed to originate from the variation of the atomic configuration which reflects the equilibrium compounds, because of the similarity in the compositional dependence among Tx, Hv and the melting temperature of the compounds. The high thermal stability of the supercooled liquid in the vicinity of Zr3Al1Ni1 seems to result from optimum bonding and packing states of the constituent atoms in the limited alloy.