I gathered that many of amorphous solids are made by quickly cooling the liquid material, thereby giving it no time to form any long-range order (crystallinity). So it makes a perfect sense that when high heat is applied to amorphous solid, it will regain its crystallinity, and will no longer be glassy.
But is this behavior non-continuous? That is, can sustained low thermal excitation give rise to the crystallinity in amorphous solids given enough time? Or is there a threshold temperature (or a level of thermal/mechanical excitation) below with no excitation can bring back the crystallinity?