Material that is flexible when cold but becomes brittle when hot I'm looking for a material that I can use to make a mesh netting.  It should be flexible and have reasonable tensile strength when cold but brittle when hot (>$\pu{400^\circ F}$).  I want to use it to contain charcoal when cold but disintegrate when charcoal is burning and some force is applied to it.

Any ideas?
It's indeed not common, as the brittle/ductile transition is usually the other way around. You can, however, find counter-examples (in a limited range of temperature) by searching for “inverse brittle-to-ductile transition”.