Copper alloy refers to an alloy formed by adding one or several other elements to pure copper. The classification of copper alloys is quite easy to understand. There are many colors of copper alloys. Non-copper types of copper alloys have different colors. Copper alloys mainly have purple, yellow, cyan and other colors.

1. Classification

1. Brass: refers to an alloy based on copper and zinc, which can be subdivided into simple brass and complex brass. The third component of complex brass is named nickel brass, silicon brass, etc.;

2. Bronze: refers to copper-based alloys other than copper-nickel and copper-zinc alloys. The main varieties are tin bronze, aluminum bronze, and special bronze (also known as high copper alloy);

3. White copper: refers to copper-nickel alloy;

4. Red copper: refers to pure copper. The main varieties include oxygen-free copper, red copper, phosphorus deoxidized copper, and silver copper.

1. Non-alloy copper: Non-alloy copper includes high-purity copper, tough copper, deoxidized copper, oxygen-free copper, etc. Traditionally, people call non-alloy copper red copper or pure copper, also called red copper.

2. Other copper alloys belong to alloy copper. my country and Russia divide copper alloys into brass, bronze and white copper, and then divide small alloy systems into major categories.

1. Copper alloys for electrical and thermal conductivity: mainly non-alloyed copper and micro-alloyed copper.

2. Structural copper alloys: including almost all copper alloys.

3. Corrosion-resistant copper alloys: mainly include tin brass, aluminum brass, various non-white copper, aluminum bronze, titanium blue, etc.

4. Wear-resistant copper alloys: mainly include complex brass, aluminum bronze, etc. containing lead, tin, aluminum, manganese and other elements.

5. Easy-cutting copper alloys: copper-lead, copper-tellurium, copper-antimony and other alloys.

6. Elastic copper alloy: mainly antimony bronze, aluminum bronze, beryllium bronze, titanium bronze, etc.

7. Damping copper alloy: high manganese copper alloy, etc.

8. Artistic copper alloy: pure copper, brass, tin bronze, aluminum bronze, white copper, etc.

1. Cast copper alloy: Casting can also be used for deformation processing.

2. Deformed copper alloy: Deformed copper alloy can be used for casting.

3. Cast copper alloys and deformed copper alloys can be subdivided into casting copper, brass, bronze and white copper.

2. The role of alloy elements

3. Alloy elements

1. Hydrogen

Hydrogen and copper do not form hydrides. The solubility of hydrogen in liquid and solid copper increases as the temperature increases, especially in liquid copper, which has a large solubility. When copper solidifies, hydrogen forms pores in the copper, causing the copper products to become brittle. In solid copper, hydrogen exists in a proton state, and the electrons of hydrogen fill the S-layer orbitals of copper atoms to form a proton solid solution. Although pure hydrogen has little effect on the performance of copper, hydrogen is harmful to copper and copper alloys. Oxygen-containing copper will produce cracks when annealed in hydrogen. Various elements have different effects on the solubility of hydrogen in copper. Among them, elements such as Ni and Mn increase the solubility, while elements such as P and Si reduce the solubility. The hydrogen content in the charge can be controlled by reducing the smelting time, adjusting the composition, and using the melt surface Charcoal covering and other methods to reduce the hydrogen content in copper.

2. Oxygen

Oxygen is inevitable in the copper production process, and its impact is also very important. Except for a very small amount of solid solution in copper, it exists in the form of Cu2O. Copper oxide is not solid-soluble in copper and forms a Cu+Cu2O eutectic structure, which is distributed at the grain boundaries. The eutectic reaction is: L containing oxygen 0.39% ---- containing oxygen 0.01% + Cu2O, in hypoeutectic copper The oxygen content of copper is directly proportional to the amount of eutectic, and the oxygen content in copper can be accurately measured by comparing it with standard pictures under a microscope.

The influence of oxygen on the properties of copper and alloys is complex. Trace amounts of oxygen have little effect on the electrical conductivity and mechanical properties of copper. Industrial copper has a high electrical conductivity. The reason is that oxygen, as a detergent, can remove many elements from copper. Harmful impurities enter the slag in the form of oxides, especially elements such as arsenic, antimony, and bismuth. The electrical conductivity of copper containing a small amount of oxygen can reach 100% to 103% IACS. High-purity copper such as 6N copper can survive under cryogenic conditions. The resistance value is quite low.

3. Antimony, bismuth, sulfur, tellurium, selenium

The solid solubility of these elements in copper is extremely small, and they are basically insoluble in copper at room temperature. They exist in the form of metal compounds and are distributed at the grain boundaries. They have little effect on the electrical and thermal conductivity of copper, but they seriously deteriorate the plasticity of copper and alloys. Processing performance, its content should be strictly controlled, and national standards stipulate that it should not exceed {{0}}.005%; because copper containing these elements has good cutting properties, it is also used in the engineering and technical circles, such as chromium copper, which can be used as a vacuum switch and circuit breaker. The contacts of the switch prevent the switch contacts from adhering when the circuit is broken. The bismuth content in bismuth copper can be as high as 0.5% to 1.0%; tellurium-copper alloy containing 0.15% to 0.5% tellurium can be used as a highly conductive, easy-to-cut stainless steel Oxygen copper can be processed into precision electronic components. As a special-purpose copper alloy, these elements can be added, but its processing technology is special, and methods such as jacket extrusion, cold extrusion, casting, and powder metallurgy can be used.

4. Arsenic, boron

Arsenic has a large solid solubility in copper, and the content in the solid solution can reach 6.8% to 7.0%. The presence of arsenic in copper strongly reduces its electrical conductivity and thermal conductivity. It is generally added as a modifier, especially for brass. Condenser alloys are even more valuable. The use of condenser tubes in thermal power plants and ships over the past 100 years has shown that brass containing 0.1% to 0.15% arsenic can prevent dezincification corrosion of brass and solve the problem of brass condenser tubes. Early leakage is a fatal problem, so various material standards stipulate that arsenic must be added. Experience shows that arsenic-free HSn70-1 condenser tubes often leak within the first 2 to 3 years of use. After adding arsenic, the service life It can be increased to 15 to 20 years, which is called a major technological progress in copper alloy research. The reason why arsenic can prevent dezincification corrosion of brass is that many studies have shown that arsenic can reduce the electrode potential of copper, thereby reducing the tendency of electrochemical corrosion. Since arsenic oxides pollute the environment and are harmful to the human body, factories that smelt alloys should have special environmental protection and protective measures; arsenic should be added in the form of master alloys, and the arsenic content in arsenic-copper master alloys can reach 15% to 30%.

Boron has a low solid solubility in copper and is generally used as a deoxidizer. The remaining boron can refine the grains. People have found that the deterioration effect is very significant. Adding {{0}}.01% to 0.04% boron to arsenic-added brass alloys has the effect of Better protection against brass dezincification and corrosion. Boron oxide is an excellent covering agent in copper alloy smelting and has been widely used. Boron is also commonly added to copper welding materials to prevent oxidation of the welding metal.

5. Phosphorus

As the temperature decreases, the solid solution amount of phosphorus in copper decreases rapidly, reaching {{0}}.6% at 300 degree and 0.4% at 200 degree . Phosphorus dissolved in copper significantly reduces its electrical conductivity. The conductivity of the soft tape containing P0.014% is 94% IACS. The conductivity of P0.14% is only 45.2%. Phosphorus is the most effective and lowest-cost deoxidizer. The presence of trace amounts can improve the fluidity of the melt, improve the weldability and corrosion resistance of copper and alloys, and increase the anti-softening temperature. Therefore, phosphorus is also the main component of copper. And valuable additive elements in alloys, phosphorus copper alloys containing P0.015% to 0.04% are widely used in the production of building water pipes, refrigeration and air conditioner heat pipes, and ship seawater pipes; low-phosphorus copper alloy plates and strips are used in Widely used in the electronics and chemical industries, integrated circuit lead frame copper strips also use a large number of low-fidelity copper alloys; phosphorus copper alloys with eutectic composition are excellent welding materials. High-copper alloys have superplasticity at 580 to 620 degree and can be heated Welding wire extruded into 3~5mm is an important material for welding copper and copper alloys, steel and copper parts.

6. Lead

Lead is not solid-soluble in copper, and its solid solubility in copper alloys is also very small. It forms a fusible eutectic structure with copper. For copper containing 0 to 38% lead, liquid lead is immiscible with liquid copper and solidifies. A monocrystalline structure is formed; in the solid state, lead is distributed in a simple state in copper and can be distributed within the grain and at the grain boundary. When a copper alloy containing lead undergoes phase change or recrystallization, the lead at the grain boundary can be transferred to the grain boundary. Inside. Lead has no significant effect on the electrical and thermal conductivity of copper and alloys, but it can improve the machinability. The lead particles are a solid phase, which is the soft phase desired for bearing materials. Therefore, lead-containing copper and alloys are valuable and easy-to-cut materials. Bearing materials are more popular in the market because of their low cost. Lead-containing brass is widely used. The smaller the lead particles, the more uniform the distribution and the better the performance. Leaded copper and alloys can be used as cast or press processed. Lead brass is a single-phase at high temperatures (above 500 degree ), has excellent hot workability, and can withstand large thermal deformation. However, it is a phase and a+ phase at room temperature. It has high deformation resistance and poor plasticity during cold deformation. , Excessive processing rate will cause cracks in the alloy material.

With the development of science and technology, the lead content of conventional lead brass has increased from 0.8% to 2.5% to more than 5%, and new lead-containing red copper, brass, bronze, and white copper are constantly being developed. In particular, it should be pointed out that lead-containing copper alloys are extremely adaptable to raw materials and can be directly produced using recycled copper, which is very important for copper processing enterprises.

7. Iron, zirconium, chromium, silicon, silver, beryllium, cadmium

The common feature of these seven metal elements is that they have limited solid solubility in copper, and their solid solubility changes drastically with temperature changes. When the temperature begins to drop after the alloy crystallization is completed, their solid solubility in copper also begins. Decrease and precipitate from the solid phase in the form of metal compounds or elemental elements. When these elements are solid dissolved in copper, they can significantly improve its strength and have a solid solution strengthening effect. When they precipitate from the solid phase, dispersion strengthening occurs. As a result, the electrical and thermal conductivity properties have been restored. They are typical aging heat-treated copper alloys. Through quenching (950~980 degree , quenching water) and aging (450~550 degree , 2-4h), high strength and high electrical conductivity properties can be obtained . Trace amounts of silver do not significantly reduce the electrical conductivity and thermal conductivity of copper, but can significantly increase the recrystallization temperature, deformation resistance and wear resistance. It is widely used in motor commutators and, more recently, in the manufacture of contact wires for high-speed trains. . Copper has the property of not generating sparks upon impact and is an important aviation instrument material. Because cadmium is toxic and pollutes the environment, its use is shrinking. Beryllium copper is the most elastic material. Beryllium strengthens copper most significantly. The strength of beryllium copper after heat treatment can reach 4 to 5 times that of pure copper.

Iron can refine grains and improve the properties of copper and alloys. In environments requiring antimagnetic properties, the iron content should be strictly controlled, generally below 0.003%.

Zirconium and chromium-copper alloys have high electrical conductivity, strength, and good softening resistance. They are the best electrode alloys and have important applications in aerospace engines.

Silicon bronze has high strength and wear resistance. Iron, zirconium and chromium bronze are the latest high-strength and high-conductivity copper alloys and have important applications in electrode manufacturing.

Iron, silicon, zirconium, and chromium-copper alloys have become the basis of copper alloys for integrated circuit lead frames, and research on their alloy composition and properties is very active.

8. Zinc, tin, aluminum, nickel

The common feature of these four elements is that they have large solid solubility in copper, which are 39.9%, 15.8% and 9.4% respectively. Nickel is infinitely soluble in each other. They form a continuous solid solution with copper and have a wide single-phase area. They can significantly improve the mechanical properties and corrosion resistance of copper, but they also reduce the electrical and thermal conductivity of copper. Compared with other metal materials , are still excellent electrical and thermal conductive materials. They form valuable alloys with copper, which can be divided into brass, bronze, and white copper alloys, forming the basis of a huge alloy system. These alloys have excellent comprehensive properties. For example, brass has high strength, wear resistance, corrosion resistance, high thermal conductivity, and low cost; bronze has high strength, wear resistance, and corrosion resistance; white copper has extremely good resistance to harsh water quality and seawater corrosion. All of these advantages are other advantages. Metal materials cannot be replaced.

9. Rare earth elements

Rare earth elements are generally almost insoluble in copper, but a small amount of rare earth metals, whether added alone or in a mixed form, are beneficial to the mechanical properties of copper and have little effect on the electrical conductivity of copper. This type of element can form high-melting-point compounds with impurities such as lead and bismuth in copper. Small spherical particles are evenly distributed in the grains, refining the grains and improving the high-temperature plasticity of steel. Adding 0.008% mixed rare earth to copper can significantly improve the process properties of copper; when adding less than 0.1% Y, the mechanical properties and process properties of copper are improved; the mechanical properties of copper alloys containing 0.01%~0.15% La Its performance, electrical conductivity, and softening resistance temperature are all better than those of Cu-0.15Ag alloy, and it has been used in industry.

10. Refractory metals and other metals

Elements such as tungsten, molybdenum, niobium, uranium, and plutonium are almost not solidly soluble in copper, while titanium, zirconium, chromium, cobalt and other elements are solidly soluble in copper in small amounts, but they all refine copper grains to varying degrees and increase its recrystallization temperature. , neutralizing the harmful effects of some fusible impurities, which is beneficial to improving high-temperature plasticity.

Copper alloys containing small amounts of zirconium (Cl5000, C15100, C18100), cobalt (C17110, C17500), and chromium (C18400, C18200, C18500) have been used in industry and have become good electrical materials.