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

Apparent activation energies (Eg) of glass transition, glass transition temperature (Tg) and crystallization temperature (Tx) of amorphous alloys of composition Fe91−xBxZr5Nb4 (FBZN, 5 ⩽ x ⩽ 30 at.%) and Fe61−xCoxZr5B30Nb4 (FCZBN, 0 ⩽ x ⩽ 15 at.%) were obtained by using differential scanning calorimeter (DSC) measurement and Kissinger equation, and correlations between Eg and Tg, Tx and glass-forming ability (GFA) were studied in the present work. It was found that the Tg and Tx are not independent each other for each glass composition in the two alloy systems, but related by a formula, Tx = αTg+β, where α and β are constants, and were measured by nonisothermally scanning in the DSC together with the Lasocka’s equation. The Eg was found to be directly proportional to α and β, respectively, and had a correlation with Tx and Tg, T x = E g - 1.09 3.527 T g - E g - 4.86 0.0041 , indicating that Eg determines linear relationship between Tx and Tg. Supercooled liquid region ΔTx is used as characterization of GFA of the Fe based metallic glasses and related to Eg and Tg by a formula: Δ T x = E g ( T g 3.527 - 234.9 ) + 1185.37 - 1.309 T g , indicating that Eg and Tg can characterize GFA of the Fe based metallic glass well.