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정의Any of a group of copper-tin alloys usually containing 0.5–10% of tin. They are generally harder, stronger in compression, and more corrosion resistant than brass. Zinc is often added, as in gunmetal (2–4% zinc), to increase strength and corrosion-resistance; bronze coins often contain more zinc (2.5%) than tin (0.5%). The presence of lead improves its machining qualities. Some copper-rich alloys containing no tin are also called bronzes. Aluminum bronzes, for example, with up to 10% aluminum, are strong, resistant to corrosion and wear, and can be worked cold or hot; silicon bronzes, with 1–5% silicon, have high corrosion-resistance; beryllium bronzes, with about 2% beryllium, are very hard and strong.