Hole-initiated melting process of thin films

Abstract

We perform numerical and experimental studies on the melting process of thin films initiated by a small hole. The presence of a non-trivial capillary surface, namely the liquid/air interface, leads to a few counter-intuitive results: (1) The melting point is elevated if the film surface is partially wettable, even with a small contact angle. (2) For a film that is finite in size, melting may prefer to start from the outer boundary, rather than a hole inside. (3) More complex melting scenario may arise, including morphology transitions, and the "de facto" melting point being a range instead of a single value. These are verified by experiments on melting alkane films between silica and air. This work continues a series of investigations on the capillary aspects on melting. Both our model and analysis approach can be easily generalized to other systems.