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

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 Fe_91-xB _xZr₅Nb₄(FBZN, 5 ≤ x ≤ 30 at.%) and Fe_61-xCo_xZr₅B₃₀Nb₄ (FCZBN, 0 ≤ x ≤ 15 at.%). It was found that the glass transition temperature T_g and the crystallization temperature T_x can be related by a formula, T_x = αT_g + 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 E_g was observed to be directly proportional to α and have a correlation, E_g = 3.527(T_x - β)/T _g +1.09, with T_x and T_g. The supercooled liquid region ΔT_x, which is used for characterization of the GFA, is related to E_g and T_g by the formula ΔT _x = (E_g/3.527-1.309)T_g+β.