Equivalence of enthalpic nature of the glasses produced by crystal-damage and melt-quenching

Abstract

Glasses can be generated by two basic strategies of melt quenching and crystal damage. However, questions regarding the similarity and difference of the glasses, in particular, their relation needs to be clarified. Here, a direct comparison of the enthalpic behaviors of the glass transition is presented in molecular glasses produced by melt quenching and ball milling. The absence of an overshoot in the upscan glass-transition heat capacity Cp curves of the milled glasses of distinct energy levels is commonly observed. The overshoot can be retrieved by either aging at temperatures below the glass transition in the milled glasses, or by heating-cooling-heating cycles around the glass transition. Heating the milled glasses can basically arrive at the same supercooled liquids as the melt-quenched glass. A strong dependence of the glass-transition Cp overshoot intensity on the fictive temperature Tf and the non-exponential parameter β is suggested in the milled glasses.