bronze

Bronze is the metal that named an age. When ancient smiths learned to melt copper with a little tin, they got an alloy far harder and tougher than either parent, hard enough for weapons, tools, statues, and bells, and human technology leapt forward. Bronze is, in its classic form, copper plus tin, though the name now stretches to copper alloyed with aluminum, silicon, or other elements too.

Adding tin to copper does two good things: the tin atoms dissolve and strengthen the copper by solid-solution strengthening, and bronze casts and flows well while resisting corrosion, especially in seawater. Different bronzes serve different jobs: tin bronze and phosphor bronze make excellent springs and bearing bushes (the metal is hard, low-friction, and wear-resistant); aluminum bronze is strong and superbly seawater-resistant for ship propellers and pump parts; silicon bronze is easy to weld and popular for sculpture and fasteners; and the classic bell and mirror bronzes have high tin for a bright ring or a reflective finish. Bronze is generally harder, stronger, and more corrosion-resistant in marine settings than brass.

Bronze earns its keep as a bearing and marine metal precisely because it is hard, low-friction, and does not rust in salt water: bushings, gears, propellers, valves, and outdoor sculpture. The honest notes: tin is expensive, so bronze usually costs more than brass; and while a bronze statue grows a stable protective patina over decades, that same green film is corrosion, just the benign, self-limiting kind. The word bronze is used loosely, so always check what a given bronze is actually alloyed with.