Thermal stability and devitrification behavior of ternary Ni-Nb-Ti and quaternary glassy alloys containing noble metals

Abstract

The devitrification of Ni 60Nb 25Ti 15 glassy alloy has been investigated by X-ray diffraction (XRD), differential scanning and isothermal calorimetry and transmission electron microscopy (TEM). The primarily crystallized phase was a cubic Ni(Ti,Nb) phase with a lattice parameter of 0.293 nm. A Ni 3Nb phase follows precipitation of the Ni(Ti,Nb) phase. The cubic Ni(Ti,Nb) phase undergoes partial transformation to Ni 4Ti 3 phase. These cubic Ni(Ti,Nb) phases disappear at the equilibrium conditions. The supercooled liquid region (ΔT x) of the Ni 60Nb 25Ti 15 glassy alloy was extended to 64 K with the addition of Pt. The Ni 55Nb 25Ti 15Pt 5 glassy alloy rods with diameters up to 2 mm were formed by mold casting. Pt and the other noble metals additions do not alter devitrification of Ni 60Nb 25Ti 15 glassy alloy. © 2005 The Japan Institute of Metals.