Co dependence of Curie temperature in amorphous Fe-Co-Zr-B-Nb alloys with high glass-forming ability

Abstract

Effects of Co substitution for Fe on the Curie temperature (Tc), glass-forming ability (GFA) and thermal stability of amorphous Fe 61-xCoxZr5B30Nb4 (FCZBN) alloys were studied for Co content ranging from 0 to 15 at. %. The Tc shows a sinusoid-like behaviour with increasing Co content, revealing two maxima at 3 and 12.5 at. % Co and a minimum at 7.5 at. % Co. Co content dependences of glass transition (Tg), crystallization (Tx) and reduced glass transition temperatures (Trg) of the amorphous alloys are almost completely opposite to that of the Tc. The T c decreases with increasing Tg and Trg, but increases with increasing Co content. The Co content dependence of the T c is suggested to relate to both Co content and high GFA of the amorphous alloys.