Compound Bronze Sword from Spring & Autumn and Warring States Period Details III

Compound bronze swords refers to those whose central ridge and edges are casted separately with different alloys. In a standard simple shape, this typical bicolor sword has a yellow ridge and greyish blue edges. The yellow ridge is made of copper-tin alloy with a percentage about 10% of tin, as this is when the alloy achieves optimal ductility based on properties of copper and tin, while an alloy consisting about 20% of tin was adopted for the greyish-tin-colored edges since this is when the alloy is hard enough to result in sharpness while maintaining a certain level of malleability. This is where the secret to compound bronze swords lies.