why is the head of a hammer made from iron not aluminum
Blacksmith Iron is different from most other materials (including bronze), in that it does not immediately go from a solid to a liquid at its melting point. H2O is a solid (ice) at -1 C (31 F), and a liquid (water) at +1 C (33 F). Iron, by contrast, is definitely a solid at 800 °F (427 °C), but over the next 1,500 °F (820 °C) it becomes increasingly plastic and more "taffy-like" as its temperature increases. This extreme temperature range of variable solidity is the fundamental material property upon which blacksmithing practice depends.