Correlations between the glass transition, crystallization, apparent activation energy and glass forming ability in Fe based amorphous alloys

Abstract

The glass transition, crystallization, apparent activation energy and glass forming ability (GFA) of a metallic glass as well as their correlations were studied in amorphous alloys of composition Fe91-xB xZr5Nb4(FBZN, 5 ≤ x ≤ 30 at.%) and Fe61-xCoxZr5B30Nb4 (FCZBN, 0 ≤ x ≤ 15 at.%). It was found that the glass transition temperature Tg and the crystallization temperature Tx can be related by a formula, Tx = αTg + β, for each amorphous alloy in the two systems, α and β are constants for a given amorphous alloy, obtained by making measurements using non-isothermal scanning at various heating rates in a differential scanning calorimeter and then applying Lasocka's equation. The apparent activation energy of the glass transition Eg was observed to be directly proportional to α and have a correlation, Eg = 3.527(Tx - β)/T g +1.09, with Tx and Tg. The supercooled liquid region ΔTx, which is used for characterization of the GFA, is related to Eg and Tg by the formula ΔT x = (Eg/3.527-1.309)Tg+β.