Relationship between specific heat and structural relaxation in Fe 40 Ni 40 B 20 metallic glass

Abstract

The structural relaxation in metallic glasses influences many technically important properties. Calorimetric investigations of relaxation have been carried out to date using only continuous heating techniques. In the present work results of isothermal annealing experiments on Fe₄₀Ni₄₀B₂₀ are reported. It was possible to divide the relaxation into reversible and irreversible contributions. The reversible relaxation occurs predominantly at higher temperatures and is ∼5–20% of the irreversible relaxation. The change in relaxation with time can be described by an exponential function. The relaxation times lay between 2·5 and 10 s. The specific heat changes by ∼1–3% for anneals between 400 and 600 K. The maximum change occurs at 500 K. The results are compared with those of other authors. Possible effects of the structural relaxation on the fracture toughness are discussed.