Recently, we conducted DSC experiments on various glassy alloys within the SeTeSnIn system. I have provided the attached DSC scans for your examination. Similar DSC scans were obtained at different heating rates as well.
Based on our observations, it appears that the presence of multiple peaks in the DSC scans can be attributed to phase separation. Our current interpretation suggests that the first peak (Endo) corresponds to the glass transition, while the second peak (Exo) signifies the process of crystallization. However, we are uncertain about the nature and origin of the additional peaks, which is causing confusion in our analysis.
At the moment I just want to point out that glass transition never looks like a peak, it shows up on the thermogram as an S-shaped fragment of the baseline, although after glass transition it is indeed possible to observe exothermic crystallization peak. Therefore, I wouldn't take peak 1 as glass transition. Rather, it can be assumed that fragments 4 in the plots correspond to glass transition
I believe that peak 1 is the glass transition, peak 2 is the crystallization, and peak 3 is the first melting point. I am using figure 2c in the attached paper to support that conclusion: Article Kinematics of glass to crystal phase transformation in novel...
Now, you may be correct about the phase separation in your sample. For example, in Se-Te systems melting occurs around 225 C (shown as peak 4). This is based on figure 3 in Article Thermal behavior in Se-Te chalcogenide system: Interplay of ...
.It appears to me that you a generating secondary alloys with increasing heat treatment. These alloys have different crystallization, glass transitions, and melting temperatures. You may be able to tease out the relative amounts of each alloy if you know the enthalpies of crystallization. You could possibly use those values and compare it to perfect crystals of each of your constituent elements or hypothesized blends.
the peak 1 is likely the so-called "enthalpy overshoot", which is a technical term for the phenomenon known as the enthalpy recovery. it occurs in a glass aged (stored) for some time below its Tg. it is incorrect to interpret this peak as the glass transition, which is not accompanied by any enthalpy change but by a small change in the heat capacity and, thus, manifests itself as a small step in DSC. in fact, the endothermic recovery peak can appear well before such step, and during it, and ultimately at the end of it (see figs 9, 10 in attached). in the latter case the heat capacity step becomes obscured by the recovery peak.
the peak 2 is likely crystallization. this peak clearly has a shoulder, meaning that at least 2 different phases crystallize. the peak 3 can be melting of one of these phases. worth comparing its T with Tm's of possible phases, if they are known. yet, it is possible that there is a liquid phase formed past Tg and it is still present so that the endotherm can be something like eutectic melting, i.e. the peak T would be markedly lower than that for the pure crystalline phase.
in all, DSC alone will not suffice to understand what is going on in this system
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