Correlations between apparent activation energy and thermostability and glass forming ability for Fe based metallic glasses

Apparent activation energies (E_g) of glass transition, glass transition temperature (T_g) and crystallization temperature (T_x) of amorphous alloys of composition Fe_91-xB_xZr₅Nb₄ (FBZN, 5 ≤ x ≤ 30 at.%) and Fe_61-xCo_xZr₅B₃₀Nb₄ (FCZBN, 0 ≤ x ≤ 15 at.%) were obtained by using differential scanning calorimeter (DSC) measurement and Kissinger equation, and correlations between E_g and T_g, T_x and glass-forming ability (GFA) were studied in the present work. It was found that the T_g and T_x are not independent each other for each glass composition in the two alloy systems, but related by a formula, T_x = αT_g+β, where α and β are constants, and were measured by nonisothermally scanning in the DSC together with the Lasocka's equation. The E_g was found to be directly proportional to α and β, respectively, and had a correlation with T_x and T_g, T_x = frac(E_g - 1.09, 3.527) T_g - frac(E_g - 4.86, 0.0041), indicating that E_g determines linear relationship between T_x and T_g. Supercooled liquid region ΔT_x is used as characterization of GFA of the Fe based metallic glasses and related to E_g and T_g by a formula: Δ T_x = E_g (frac(T_g, 3.527) - 234.9) + 1185.37 - 1.309 T_g, indicating that E_g and T_g can characterize GFA of the Fe based metallic glass well.