STUDY OF GLASS TRANSITION KINETICS FOR Co₆₆Si₁₂B₁₆Fe₄Mo₂ METALLIC GLASS

Abstract

Metallic glasses have received considerable attention in comparison to normal metallic materials due to their superior physical, mechanical, electrical and magnetic properties. Understanding the glass transition kinetics of metallic alloys is of great importance in order to know its thermal stability. In the present paper, kinetics of glass transition of metallic glass Co 66 Si 12 B 16 Fe 4 Mo 2 is studied using thermal analysis technique, i.e. differential scanning calorimetry (DSC), by nonisothermal heating of the sample at four different heating rates. The activation energy (E) of the glass transition region is determined by two most frequently used methods, namely, Moynihan's method and Kissinger's equation. The fragility index, m is also calculated using T g , which is a measure of glass forming ability of the given system. The results show that the fragility index 'm' of the given system falls below 16. This clearly indicates that the given system is strong liquid with excellent glass forming ability (GFA).

Theoretical modelling of kinetics of glass transition temperature of PEG toughened epoxy

“…From the graphs it is understood that the heating rates have much influence on the glass transition temperature. As the heating rate increases, the T g values also increases which is in accordance with the literature [19-22]. It is also seen that the T g and Δ C p values follow the same trend irrespective of the heating rate.…”

“…The growing viscosity rate of a supercooled liquid during the process of cooling is termed as fragility. From the fragility index value, m,the glassy liquids are usually categorised into strong and fragile liquids [19, 20, 22]. This ‘ m ’ value indicates the rate of decrease of the relaxation time with an increase in temperature around T g and is given by …”

“…It depends on the immobilised polymer region (X i ). A good filler will interact well with the polymer matrix and hence will have a drastic reduction in the ΔC p value [19][20][21]. The change in the ΔC p values is tabulated in Table 1.…”