Curie temp is specific to magnetic (and electric) materials, which tungsten and other ordinary metals aren't. That reference appears to be abusing the term, with whatever material their PTCs are made of. Resistivity does not change suddenly in materials that do exhibit a Curie temp.
PTCs used for fusing applications, as far as I know, can't be more different, physically: they use conductive particles in a polymer matrix, which expands and becomes highly resistive when heated.
As far as I know, normal metals (and alloys) exhibit various sorts of humps and plateaus at lower temperatures, but always have a general R ~ T^2, or other generally rising power or polynomial shape, especially at higher temperatures (including up to, and beyond, the melting point). I don't know the mechanics of it, but some alloys have dips and humps, which can be controlled by composition, resulting in a low tempco around room temperature, or over a specified range. But always PTC in the grander scheme of things.
Tim