Copper alloys have excellent material properties and can be used in many scenarios. Pure copper has been one of the most important metals for thousands of years, and its greatest advantages over other metals are:
Good electrical conductivity, high thermal conductivity, outstanding combination of strength and plasticity, corrosion resistance in many environments.
Many of the properties of copper, including diamagnetism, are also present in its alloys, and various alloying elements add other desirable properties. Despite the relatively high price of copper, its alloys brass, bronze and cupronickel are still firmly established in various fields, including engineering.
brass
Adding zinc to copper increases the strength of the alloy and at the same time, its plasticity increases, which is a very important feature.
10-20% zinc alloys are known as gilded metals and are used in the jewelry industry and in the production of heat exchangers; 30% zinc alloys are known as cartridge brass. The highest threshold for zinc in formable brass is about 35%.
Adding other alloying elements can further improve the properties of brass. For example, tin and aluminum increase its corrosion resistance in seawater.
single phase brass
Applications: Jewelry, Artwork, Tableware, Musical Instruments and Cartridges. Single-phase brass has a zinc content of up to 37%, known as alpha brass, has a uniform crystal structure, is softer, and is more ductile. These qualities make Alpha Brass suitable for cold working, drawing, bending and other processes.
Duplex Brass
Applications: heat exchangers, capacitors, parts made from automatic cutting tables, etc. Duplex brass contains both α and β phases, ie both α grain structure and β grain structure are present. Duplex brass is less expensive than single-phase brass because it uses a lot of zinc, and it is also susceptible to corrosion. Its chemical composition gives it greater strength and hardness, making it suitable for processes such as thermoforming and casting.
bronze
Bronze alloys are divided into different classes according to the alloying elements used.
Tin Bronze
Applications: springs, washers, coins, handicrafts, pump parts, pressure-resistant castings, bearings, etc. Its application depends on the percentage of tin used in the alloy. The maximum tin content in alloys suitable for cold working is about 7%, and these copper alloys have good plasticity. The maximum tin content is about 20%, from 5% tin the structure of the alloy changes and some additional heat treatment is required which results in a porous structure which also makes them unsuitable for other forming methods than casting reason. The main application of duplex tin bronze is in the bearing industry, this structure has a good balance, where the alpha phase ensures the impact resistance, while the hard and brittle compound carries the load and provides some wear resistance. Zinc and lead are also sometimes present in tin bronze. Zinc improved the quality of the castings and also made the alloy cheaper. This bronze was also known as gun bronze because large guns were made of this material in the past. A small amount of lead helps to improve the cutting mechanical properties of bronze. The lead content in lead bronze used as bearing material is relatively high (25% higher than Z).
Aluminum Bronze
Applications: coins, ship parts, ship hardware, sleeve bearings, pumps, valves and more. Aluminum bronze has similar properties to tin bronze, mostly single phase and suitable for cold forming, very suitable for making coins, where the aluminum content is usually between 6-12%. Duplex aluminum bronzes can be used as casting alloys or for hot working. Aluminum bronze, with an aluminum content of about 10%, is used to make propellers, valves, pumps, etc.
Cupronickel
Applications: coins, marine equipment, electrical equipment, heat exchangers, cooling systems, shipbuilding, etc. Copper-nickel alloys are strong and highly malleable. The addition of nickel (typically 2-30%) to copper makes the metal highly corrosion resistant and has excellent electrical conductivity. Copper-nickel alloy has almost no coefficient of thermal expansion at 40…50% nickel, and the resistance is also the largest, so Constantan (Cu-Ni alloy with 45% nickel) is used for electrical equipment with large temperature changes. Corrosion-resistant copper-nickel alloys contain approximately 30% nickel, with small amounts of iron and manganese, and are particularly stable in salt water.