Relation between time–temperature transformation and continuous heating transformation diagrams of metallic glassy alloys

Abstract

The time–temperature transformation (TTT) diagrams for the onset of devitrification of the Ge–Ni–La and Cu–Hf–Ti glassy alloys were calculated from the isothermal differential calorimetry data using an Arrhenius equation. The continuous heating transformation (CHT) diagrams for the onset of devitrification of the glassy alloys were subsequently recalculated from TTT diagrams. The recalculation method used for conversion of the TTT into CHT diagrams produces reasonable results and is not sensitive to the type of the devitrification reaction (polymorphous or primary transformation). The diagrams allow to perform a comparison of the stabilities of glassy alloys on a long-term scale. The relationship between these diagrams is discussed.