Synthesis and crystallisation of Fe–Co–Ni–Zr(Nb)–B bulk glasses

Abstract

Bulk glass formation in multicomponent Fe–Co–Ni–Zr–B and Fe–Co–Ni–Zr–Nb–B alloy systems has been investigated by means of casting in a wedge shaped copper mould. It is observed that the critical thickness for glass formation, thermal stability of the glass and the undercooled liquid region increase upon the addition of niobium. The coercivity increases abruptly above the critical thickness owing to disappearance of the amorphous phase. Amorphous ribbons of both alloy systems have been prepared with various zirconium and boron contents to obtain a spectrum of values for glass transition, crystallisation temperature and undercooled liquid region. Kinetics studies of crystallisation have revealed that the activation energy increases with increasing undercooled liquid region.

Keywords:

• BULK GLASS
• UNDERCOOLED LIQUID REGION
• GLASS TRANSITION
• CRYSTALLISATION TEMPERATURE
• ACTIVATION ENERGY
• COERCIVITY